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Author SHA1 Message Date
Yu Zhao
cc8ec7be78 mm/mglru: optimize deactivation 
Do not shuffle a folio in the deactivation paths if it is already in the
oldest generation.  This reduces the LRU lock contention.

Before this patch, the contention is reproducible by FIO, e.g.,

  fio -filename=/dev/nvme1n1p2 -direct=0 -thread -size=1024G \
      -rwmixwrite=30  --norandommap --randrepeat=0 -ioengine=sync \
      -bs=4k -numjobs=400 -runtime=25000 --time_based \
      -group_reporting -name=mglru

  98.96%--_raw_spin_lock_irqsave
          folio_lruvec_lock_irqsave
          |
           --98.78%--folio_batch_move_lru
               |
                --98.63%--deactivate_file_folio
                          mapping_try_invalidate
                          invalidate_mapping_pages
                          invalidate_bdev
                          blkdev_common_ioctl
                          blkdev_ioctl

After this patch, deactivate_file_folio() bails out early without taking
the LRU lock.

A side effect is that a folio can be left at the head of the oldest
generation, rather than the tail.  If reclaim happens at the same time, it
cannot reclaim this folio immediately.  Since there is no known
correlation between truncation and reclaim, this side effect is considered
insignificant.

Link: https://lkml.kernel.org/r/20241231043538.4075764-3-yuzhao@google.com
Reported-by: Bharata B Rao <bharata@amd.com>
Closes: https://lore.kernel.org/CAOUHufawNerxqLm7L9Yywp3HJFiYVrYO26ePUb1jH-qxNGWzyA@mail.gmail.com/
Signed-off-by: Yu Zhao <yuzhao@google.com>
Tested-by: Kalesh Singh <kaleshsingh@google.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: David Stevens <stevensd@chromium.org>
Cc: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:38 -08:00
Yu Zhao
9cbfd1c3c8 mm/mglru: clean up workingset 
Patch series "mm/mglru: performance optimizations", v4.

This series improves performance for some previously reported test cases. 
Most of the code changes gathered here has been floating on the mailing
list [1][2].  They are now properly organized and have gone through
various benchmarks on client and server devices, including Android, FIO,
memcached, multiple VMs and MongoDB.

In addition to the syzbot regressions fixed in v2 [3] and v3 [4], this
version fixes two more regressions: one reported by Oliver Sang [5] and
the other by Barry Song.

[1] https://lore.kernel.org/CAOUHufahuWcKf5f1Sg3emnqX+cODuR=2TQo7T4Gr-QYLujn4RA@mail.gmail.com/
[2] https://lore.kernel.org/CAOUHufawNerxqLm7L9Yywp3HJFiYVrYO26ePUb1jH-qxNGWzyA@mail.gmail.com/
[3] https://lore.kernel.org/67294349.050a0220.701a.0010.GAE@google.com/
[4] https://lore.kernel.org/67549eca.050a0220.2477f.001b.GAE@google.com/
[5] https://lore.kernel.org/202412231601.f1eb8f84-lkp@intel.com/


This patch (of 7):

Move VM_BUG_ON_FOLIO() to cover both the default and MGLRU paths.  Also
use a pair of rcu_read_lock() and rcu_read_unlock() within each path, to
improve readability.

This change should not have any side effects.

Link: https://lkml.kernel.org/r/20241231043538.4075764-1-yuzhao@google.com
Link: https://lkml.kernel.org/r/20241231043538.4075764-2-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Tested-by: Kalesh Singh <kaleshsingh@google.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Bharata B Rao <bharata@amd.com>
Cc: David Stevens <stevensd@chromium.org>
Cc: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:38 -08:00
Guo Weikang
c6f239796b mm/memblock: add memblock_alloc_or_panic interface 
Before SLUB initialization, various subsystems used memblock_alloc to
allocate memory.  In most cases, when memory allocation fails, an
immediate panic is required.  To simplify this behavior and reduce
repetitive checks, introduce `memblock_alloc_or_panic`.  This function
ensures that memory allocation failures result in a panic automatically,
improving code readability and consistency across subsystems that require
this behavior.

[guoweikang.kernel@gmail.com: arch/s390: save_area_alloc default failure behavior changed to panic]
  Link: https://lkml.kernel.org/r/20250109033136.2845676-1-guoweikang.kernel@gmail.com
  Link: https://lore.kernel.org/lkml/Z2fknmnNtiZbCc7x@kernel.org/
Link: https://lkml.kernel.org/r/20250102072528.650926-1-guoweikang.kernel@gmail.com
Signed-off-by: Guo Weikang <guoweikang.kernel@gmail.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>	[m68k]
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>	[s390]
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:38 -08:00
Lorenzo Stoakes
f8d4a6cabb mm: make mmap_region() internal 
Now that we have removed the one user of mmap_region() outside of mm, make
it internal and add it to vma.c so it can be userland tested.

This ensures that all external memory mappings are performed using the
appropriate interfaces and allows us to modify memory mapping logic as we
see fit.

Additionally expand test stubs to allow for the mmap_region() code to
compile and be userland testable.

Link: https://lkml.kernel.org/r/de5a3c574d35c26237edf20a1d8652d7305709c9.1735819274.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:38 -08:00
Kairui Song
4f79384a25 mm, swap_slots: remove slot cache for freeing path 
The slot cache for freeing path is mostly for reducing the overhead of
si->lock.  As we have basically eliminated the si->lock usage for freeing
path, it can be removed.

This helps simplify the code, and avoids swap entries from being hold in
cache upon freeing.  The delayed freeing of entries have been causing
trouble for further optimizations for zswap [1] and in theory will also
cause more fragmentation, and extra overhead.

Test with build linux kernel showed both performance and fragmentation is
better without the cache:

tiem make -j96 / 768M memcg, 4K pages, 10G ZRAM, avg of 4 test run::
Before:
Sys time: 36047.78, Real time: 472.43
After: (-7.6% sys time, -7.3% real time)
Sys time: 33314.76, Real time: 437.67

time make -j96 / 1152M memcg, 64K mTHP, 10G ZRAM, avg of 4 test run:
Before:
Sys time: 46859.04, Real time: 562.63
hugepages-64kB/stats/swpout: 1783392
hugepages-64kB/stats/swpout_fallback: 240875
After: (-23.3% sys time, -21.3% real time)
Sys time: 35958.87, Real time: 442.69
hugepages-64kB/stats/swpout: 1866267
hugepages-64kB/stats/swpout_fallback: 158330

Sequential SWAP should be also slightly faster, tests didn't show a
measurable difference though, at least no regression:

Swapin 4G zero page on ZRAM (time in us):
Before (avg. 1923756)
1912391 1927023 1927957 1916527 1918263 1914284 1934753 1940813 1921791
After (avg. 1922290):
1919101 1925743 1916810 1917007 1923930 1935152 1917403 1923549 1921913

Link: https://lore.kernel.org/all/CAMgjq7ACohT_uerSz8E_994ZZCv709Zor+43hdmesW_59W1BWw@mail.gmail.com/[1]
Link: https://lkml.kernel.org/r/20250113175732.48099-14-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Suggested-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:37 -08:00
Kairui Song
bae8a4ef3e mm, swap: use a global swap cluster for non-rotation devices 
Non-rotational devices (SSD / ZRAM) can tolerate fragmentation, so the
goal of the SWAP allocator is to avoid contention for clusters.  It uses a
per-CPU cluster design, and each CPU will use a different cluster as much
as possible.

However, HDDs are very sensitive to fragmentation, contention is trivial
in comparison.  Therefore, we use one global cluster instead.  This
ensures that each order will be written to the same cluster as much as
possible, which helps make the I/O more continuous.

This ensures that the performance of the cluster allocator is as good as
that of the old allocator.  Tests after this commit compared to those
before this series:

Tested using 'make -j32' with tinyconfig, a 1G memcg limit, and HDD swap:

make -j32 with tinyconfig, using 1G memcg limit and HDD swap:

Before this series:
114.44user 29.11system 39:42.90elapsed 6%CPU (0avgtext+0avgdata 157284maxresident)k
2901232inputs+0outputs (238877major+4227640minor)pagefaults

After this commit:
113.90user 23.81system 38:11.77elapsed 6%CPU (0avgtext+0avgdata 157260maxresident)k
2548728inputs+0outputs (235471major+4238110minor)pagefaults

[ryncsn@gmail.com: check kmalloc() return in setup_clusters]
  Link: https://lkml.kernel.org/r/CAMgjq7Au+o04ckHyT=iU-wVx9az=t0B-ZiC5E0bDqNrAtNOP-g@mail.gmail.com
Link: https://lkml.kernel.org/r/20250113175732.48099-13-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Suggested-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:37 -08:00
Kairui Song
3f641cf938 mm, swap: introduce a helper for retrieving cluster from offset 
It's a common operation to retrieve the cluster info from offset,
introduce a helper for this.

Link: https://lkml.kernel.org/r/20250113175732.48099-12-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Suggested-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:37 -08:00
Kairui Song
e3ae2dec84 mm, swap: simplify percpu cluster updating 
Instead of using a returning argument, we can simply store the next
cluster offset to the fixed percpu location, which reduce the stack usage
and simplify the function:

Object size:
./scripts/bloat-o-meter mm/swapfile.o mm/swapfile.o.new
add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-271 (-271)
Function                                     old     new   delta
get_swap_pages                              2847    2733    -114
alloc_swap_scan_cluster                      894     737    -157
Total: Before=30833, After=30562, chg -0.88%

Stack usage:
Before:
swapfile.c:1190:5:get_swap_pages       240    static

After:
swapfile.c:1185:5:get_swap_pages       216    static

Link: https://lkml.kernel.org/r/20250113175732.48099-11-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chis Li <chrisl@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:37 -08:00
Kairui Song
3b644773ee mm, swap: reduce contention on device lock 
Currently, swap locking is mainly composed of two locks: the cluster lock
(ci->lock) and the device lock (si->lock).

The cluster lock is much more fine-grained, so it is best to use ci->lock
instead of si->lock as much as possible.

We have cleaned up other hard dependencies on si->lock.  Following the new
cluster allocator design, most operations don't need to touch si->lock at
all.  In practice, we only need to take si->lock when moving clusters
between lists.

To achieve this, this commit reworks the locking pattern of all si->lock
and ci->lock users, eliminates all usage of ci->lock inside si->lock, and
introduces a new design to avoid touching si->lock unless needed.

For minimal contention and easier understanding of the system, two ideas
are introduced with the corresponding helpers: isolation and relocation.

- Clusters will be `isolated` from the list when iterating the list
  to search for an allocatable cluster.

  This ensures other CPUs won't walk into the same cluster easily,
  and it releases si->lock after acquiring ci->lock, providing the
  only place that handles the inversion of two locks, and avoids
  contention.

  Iterating the cluster list almost always moves the cluster
  (free -> nonfull, nonfull -> frag, frag -> frag tail), but it
  doesn't know where the cluster should be moved to until scanning
  is done. So keeping the cluster off-list is a good option with
  low overhead.

  The off-list time window of a cluster is also minimal. In the worst
  case, one CPU will return the cluster after scanning the 512 entries
  on it, which we used to busy wait with a spin lock.

This is done with the new helper `isolate_lock_cluster`.

- Clusters will be `relocated` after allocation or freeing, according
  to their usage count and status.

  Allocations no longer hold si->lock now, and may drop ci->lock for
  reclaim, so the cluster could be moved to any location while no lock
  is held. Besides, isolation clears all flags when it takes the
  cluster off the list (the flags must be in sync with the list status,
  so cluster users don't need to touch si->lock for checking its list
  status). So the cluster has to be relocated to the right list
  according to its usage after allocation or freeing.

  Relocation is optional, if the cluster flags indicate it's already
  on the right list, it will skip touching the list or si->lock.

This is done with `relocate_cluster` after allocation or with
`[partial_]free_cluster` after freeing.

This handled usage of all kinds of clusters in a clean way.

Scanning and allocation by iterating the cluster list is handled by
"isolate - <scan / allocate> - relocate".

Scanning and allocation of per-CPU clusters will only involve
"<scan / allocate> - relocate", as it knows which cluster to lock
and use.

Freeing will only involve "relocate".

Each CPU will keep using its per-CPU cluster until the 512 entries
are all consumed. Freeing also has to free 512 entries to trigger
cluster movement in the best case, so si->lock is rarely touched.

Testing with building the Linux kernel with defconfig showed huge
improvement:

tiem make -j96 / 768M memcg, 4K pages, 10G ZRAM, on Intel 8255C:
Before:
Sys time: 73578.30, Real time: 864.05
After: (-50.7% sys time, -44.8% real time)
Sys time: 36227.49, Real time: 476.66

time make -j96 / 1152M memcg, 64K mTHP, 10G ZRAM, on Intel 8255C:
(avg of 4 test run)
Before:
Sys time: 74044.85, Real time: 846.51
hugepages-64kB/stats/swpout: 1735216
hugepages-64kB/stats/swpout_fallback: 430333

After: (-40.4% sys time, -37.1% real time)
Sys time: 44160.56, Real time: 532.07
hugepages-64kB/stats/swpout: 1786288
hugepages-64kB/stats/swpout_fallback: 243384

time make -j32 / 512M memcg, 4K pages, 5G ZRAM, on AMD 7K62:
Before:
Sys time: 8098.21, Real time: 401.3
After: (-22.6% sys time, -12.8% real time )
Sys time: 6265.02, Real time: 349.83

The allocation success rate also slightly improved as we sanitized the
usage of clusters with new defined helpers, previously dropping
si->lock or ci->lock during scan will cause cluster order shuffle.

Link: https://lkml.kernel.org/r/20250113175732.48099-10-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Suggested-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:37 -08:00
Kairui Song
3494d18470 mm, swap: use an enum to define all cluster flags and wrap flags changes 
Currently, we are only using flags to indicate which list the cluster is
on.  Using one bit for each list type might be a waste, as the list type
grows, we will consume too many bits.  Additionally, the current mixed
usage of '&' and '==' is a bit confusing.

Make it clean by using an enum to define all possible cluster statuses. 
Only an off-list cluster will have the NONE (0) flag.  And use a wrapper
to annotate and sanitize all flag settings and list movements.

Link: https://lkml.kernel.org/r/20250113175732.48099-9-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Suggested-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:36 -08:00
Kairui Song
9a0ddeb798 mm, swap: hold a reference during scan and cleanup flag usage 
The flag SWP_SCANNING was used as an indicator of whether a device is
being scanned for allocation, and prevents swapoff.  Combined with
SWP_WRITEOK, they work as a set of barriers for a clean swapoff:

1. Swapoff clears SWP_WRITEOK, allocation requests will see
   ~SWP_WRITEOK and abort as it's serialized by si->lock.
2. Swapoff unuses all allocated entries.
3. Swapoff waits for SWP_SCANNING flag to be cleared, so ongoing
   allocations will stop, preventing UAF.
4. Now swapoff can free everything safely.

This will make the allocation path have a hard dependency on si->lock. 
Allocation always have to acquire si->lock first for setting SWP_SCANNING
and checking SWP_WRITEOK.

This commit removes this flag, and just uses the existing per-CPU refcount
instead to prevent UAF in step 3, which serves well for such usage without
dependency on si->lock, and scales very well too.  Just hold a reference
during the whole scan and allocation process.  Swapoff will kill and wait
for the counter.

And for preventing any allocation from happening after step 1 so the unuse
in step 2 can ensure all slots are free, swapoff will acquire the ci->lock
of each cluster one by one to ensure all allocations see ~SWP_WRITEOK and
abort.

This way these dependences on si->lock are gone.  And worth noting we
can't kill the refcount as the first step for swapoff as the unuse process
have to acquire the refcount.

Link: https://lkml.kernel.org/r/20250113175732.48099-8-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chis Li <chrisl@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:36 -08:00
Kairui Song
b228386cf2 mm, swap: clean up plist removal and adding 
When the swap device is full (inuse_pages == pages), it should be removed
from the allocation available plist.  If any slot is freed, the swap
device should be added back to the plist.  Additionally, during swapon or
swapoff, the swap device is forcefully added or removed.

Currently, the condition (inuse_pages == pages) is checked after every
counter update, then remove or add the device accordingly.  This is
serialized by si->lock.

This commit decouples it from the protection of si->lock and reworked
plist removal and adding, making it possible to get rid of the hard
dependency on si->lock in allocation path in later commits.

To achieve this, simply using another lock is not an optimal approach, as
the overhead is observable for a hot counter, and may cause complex
locking issues.  Thus, this commit manages to make it a lock-free atomic
operation, by embedding the plist state into the second highest bit of the
atomic counter.

Simply making the counter an atomic will not work, if the update and plist
status check are not performed atomically, we may miss an addition or
removal.  With the embedded info we can update the counter and check the
plist status with single atomic operations, and avoid any extra overheads:

If the counter is full (inuse_pages == pages) and the off-list bit is
unset, we attempt to remove it from the plist.  If the counter is not full
(inuse_pages != pages) and the off-list bit is set, we attempt to add it
to the plist.  Removing, adding and bit update is serialized with a lock,
which is a cold path.  Ordinary counter updates will be lock-free.

Link: https://lkml.kernel.org/r/20250113175732.48099-7-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chis Li <chrisl@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:36 -08:00
Kairui Song
27701521be mm, swap: clean up device availability check 
Remove highest_bit and lowest_bit.  After the HDD allocation path has been
removed, the only purpose of these two fields is to determine whether the
device is full or not, which can instead be determined by checking the
inuse_pages.

Link: https://lkml.kernel.org/r/20250113175732.48099-6-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chis Li <chrisl@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:36 -08:00
Kairui Song
0b310d9cfd mm, swap: use cluster lock for HDD 
Cluster lock (ci->lock) was introduced to reduce contention for certain
operations.  Using cluster lock for HDD is not helpful as HDD have a poor
performance, so locking isn't the bottleneck.  But having different set of
locks for HDD / non-HDD prevents further rework of device lock (si->lock).

This commit just changed all lock_cluster_or_swap_info to lock_cluster,
which is a safe and straight conversion since cluster info is always
allocated now, also removed all cluster_info related checks.

Link: https://lkml.kernel.org/r/20250113175732.48099-5-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Suggested-by: Chris Li <chrisl@kernel.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:36 -08:00
Kairui Song
7277433096 mm, swap: remove old allocation path for HDD 
We are currently using different swap allocation algorithm for HDD and
non-HDD.  This leads to the existence of a different set of locks, and the
code path is heavily bloated, causing difficulties for further
optimization and maintenance.

This commit removes all HDD swap allocation and related dead code, and
uses the cluster allocation algorithm instead.

The performance may drop temporarily, but this should be negligible: The
main advantage of the legacy HDD allocation algorithm is that it tends to
use continuous slots, but swap device gets fragmented quickly anyway, and
the attempt to use continuous slots will fail easily.

This commit also enables mTHP swap on HDD, which is expected to be
beneficial, and following commits will adapt and optimize the cluster
allocator for HDD.

Link: https://lkml.kernel.org/r/20250113175732.48099-4-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Suggested-by: Chris Li <chrisl@kernel.org>
Suggested-by: "Huang, Ying" <ying.huang@linux.alibaba.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:36 -08:00
Kairui Song
e027ec414f mm, swap: fold swap_info_get_cont in the only caller 
The name of the function is confusing, and the code is much easier to
follow after folding, also rename the confusing naming "p" to more
meaningful "si".

Link: https://lkml.kernel.org/r/20250113175732.48099-3-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chis Li <chrisl@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:36 -08:00
Kairui Song
d563ced682 mm, swap: minor clean up for swap entry allocation 
Patch series "mm, swap: rework of swap allocator locks", v4.

This series greatly improved swap performance by reworking the locking
design and simplify a lot of code path.  Test showed a up to 400%
vm-scalability improvement with pmem as SWAP, and up to 37% reduce of
kernel compile real time with ZRAM as SWAP (up to 60% improvement in
system time).

This is part of the new swap allocator discussed during the "Swap
Abstraction" discussion at LSF/MM 2024, and "mTHP and swap allocator"
discussion at LPC 2024.

This is a follow up of previous swap cluster allocator series:
https://lore.kernel.org/linux-mm/20240730-swap-allocator-v5-0-cb9c148b9297@kernel.org/
Also enables further optimizations which will come later.

Previous series introduced a fully cluster based allocator, this series
completely get rid of the old allocator and makes the new allocator avoid
touching the si->lock unless needed.  This bring huge performance gain and
get rid of slot cache for freeing path.

Currently, swap locking is mainly composed of two locks, cluster lock
(ci->lock) and device lock (si->lock).  The device lock is widely used to
protect many things, causing it to be the main bottleneck for SWAP.

Cluster lock is much more fine-grained, so it will be best to use ci->lock
instead of si->lock as much as possible.

`perf lock' indicates this issue clearly.  Doing linux kernel build using
tmpfs and ZRAM with limited memory (make -j64 with 1G memcg and 4k pages),
result of "perf lock contention -ab sleep 3" shows:

  contended   total wait     max wait     avg wait         type   caller
     34948     53.63 s       7.11 ms      1.53 ms     spinlock   free_swap_and_cache_nr+0x350
     16569     40.05 s       6.45 ms      2.42 ms     spinlock   get_swap_pages+0x231
     11191     28.41 s       7.03 ms      2.54 ms     spinlock   swapcache_free_entries+0x59
      4147     22.78 s     122.66 ms      5.49 ms     spinlock   page_vma_mapped_walk+0x6f3
      4595      7.17 s       6.79 ms      1.56 ms     spinlock   swapcache_free_entries+0x59
    406027      2.74 s       2.59 ms      6.74 us     spinlock   list_lru_add+0x39
  ...snip...

The top 5 caller are all users of si->lock, total wait time sums to
several minutes in the 3 seconds time window.

Following the new allocator design, many operation doesn't need to touch
si->lock at all.  We only need to take si->lock when doing operations
across multiple clusters (changing the cluster list).  So ideally
allocator should always take ci->lock first, then take si->lock only if
needed.  But due to historical reasons, ci->lock is used inside si->lock
critical section, causing lock inversion if we simply try to acquire
si->lock after acquiring ci->lock.

This series audited all si->lock usage, clean up legacy codes, eliminate
usage of si->lock as much as possible by introducing new designs based on
the new cluster allocator.

Old HDD allocation codes are removed, cluster allocator is adapted with
small changes for HDD usage, test is looking OK.

And this also removed slot cache for freeing path.  The performance is
even better without it now, and this enables other clean up and
optimizations as discussed before:

https://lore.kernel.org/all/CAMgjq7ACohT_uerSz8E_994ZZCv709Zor+43hdmesW_59W1BWw@mail.gmail.com/

After this series, lock contention on si->lock is nearly unobservable
with `perf lock` with the same test above:

  contended   total wait     max wait     avg wait         type   caller
  ... snip ...
        52    127.12 us      3.82 us      2.44 us     spinlock   move_cluster+0x2c
        56    120.77 us     12.41 us      2.16 us     spinlock   move_cluster+0x2c
  ... snip ...
        10     21.96 us      2.78 us      2.20 us     spinlock   isolate_lock_cluster+0x20
  ... snip ...
         9     19.27 us      2.70 us      2.14 us     spinlock   move_cluster+0x2c
  ... snip ...
         5     11.07 us      2.70 us      2.21 us     spinlock   isolate_lock_cluster+0x20

`move_cluster' and `isolate_lock_cluster' (two new introduced helper) are
basically the only users of si->lock now, performance gain is huge, and
LOC is reduced.

Tests Results:

vm-scalability
==============
Running `usemem --init-time -O -y -x -R -31 1G` from vm-scalability in a
12G memory cgroup using simulated pmem as SWAP backend (32G pmem, 32
CPUs).

Using 4K folio by default, 64k mTHP and sequential access (!-R) results
are also provided. 6 test runs for each case, Total Throughput:

Test             Before (KB/s) (stdev)  After (KB/s) (stdev)   Delta
---------------------------------------------------------------------------
Random (4K):     69937.11 (16449.77)    369816.17  (24476.68)  +428.78%
Random (64k):    123442.83 (13207.51)   216379.00  (25024.83)  +75.28%
Sequential (4K): 6313909.83 (148856.12) 6419860.66 (183563.38) +1.7%

Sequential access will cause lower stress for the allocator so the gain is
limited, but with random access (which is much closer to real workloads)
the performance gain is huge.

Build kernel with defconfig on tmpfs with ZRAM
==============================================
Below results shows a test matrix using different memory cgroup limit and
job numbets, and scaled up progressive for a intuitive result.  Done on a
48c96t system.

6 test run for each case, it can be seen clearly that as concurrent job
number goes higher the performance gain is higher, but even -j6 is showing
slight improvement.

   make -j<NR>     |   System Time (seconds)  |   Total Time (seconds)
 (NR / Mem / ZRAM) | (Before / After / Delta) | (Before / After / Delta)
 With 4k pages only:
  6 / 192M / 3G    |    1533 /  1522 / -0.7%  |    1420 /  1414 / -0.3%
 12 / 256M / 4G    |    2275 /  2226 / -2.2%  |     758 /   742 / -2.1%
 24 / 384M / 5G    |    3596 /  3154 / -12.3% |     476 /   422 / -11.3%
 48 / 768M / 7G    |    8159 /  3605 / -55.8% |     330 /   221 / -33.0%
 96 / 1.5G / 10G   |   18541 /  6462 / -65.1% |     283 /   180 / -36.4%
 With 64k mTHP:
 24 / 512M / 5G    |    3585 /  3469 /  -3.2% |     293 /   290 / -0.1%
 48 /   1G / 7G    |    8173 /  3607 / -55.9% |     251 /   158 / -37.0%
 96 /   2G / 10G   |   16305 /  7791 / -52.2% |     226 /   144 / -36.3%

The fragmentation are reduced too:
With: make -j96 / 1152M memcg, 64K mTHP:
(avg of 4 test run)
Before:
hugepages-64kB/stats/swpout: 1696184
hugepages-64kB/stats/swpout_fallback: 414318
After: (-63.2% mTHP swapout failure)
hugepages-64kB/stats/swpout: 1866267
hugepages-64kB/stats/swpout_fallback: 158330

There is a up to 65.1% improvement in sys time for build kernel test,
and lower fragmentation rate.

Build kernel with tinyconfig on tmpfs with HDD as swap:
=======================================================

This test is similar to above, but HDD test is very noisy and slow, the
deviation is huge, so just use tinyconfig instead and take the median test
result of 3 test run, which looks OK:

Before this series:
114.44user 29.11system 39:42.90elapsed 6%CPU
2901232inputs+0outputs (238877major+4227640minor)pagefaults

After this commit:
113.90user 23.81system 38:11.77elapsed 6%CPU
2548728inputs+0outputs (235471major+4238110minor)pagefaults

Single thread SWAP:
===================

Sequential SWAP should also be slightly faster as we removed a lot of
unnecessary parts. Test using micro benchmark for swapout/in 4G
zero memory using ZRAM, 10 test runs:

Swapout Before (avg. 3359304):
3353796 3358551 3371305 3356043 3367524 3355303 3355924 3354513 3360776

Swapin Before (avg. 1928698):
1920283 1927183 1934105 1921373 1926562 1938261 1927726 1928636 1934155

Swapout After (avg. 3347511, -0.4%):
3337863 3347948 3355235 3339081 3333134 3353006 3354917 3346055 3360359

Swapin After (avg. 1922290, -0.3%):
1919101 1925743 1916810 1917007 1923930 1935152 1917403 1923549 1921913

The gain is limited at noise level but seems slightly better.


This patch (of 13):

Direct reclaim can skip the whole folio after reclaimed a set of folio
based slots.  Also simplify the code for allocation, reduce indention.

Link: https://lkml.kernel.org/r/20250113175732.48099-1-ryncsn@gmail.com
Link: https://lkml.kernel.org/r/20250113175732.48099-2-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chis Li <chrisl@kernel.org> (Google)
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:35 -08:00
Chen Ridong
ade81479c7 memcg: fix soft lockup in the OOM process 
A soft lockup issue was found in the product with about 56,000 tasks were
in the OOM cgroup, it was traversing them when the soft lockup was
triggered.

watchdog: BUG: soft lockup - CPU#2 stuck for 23s! [VM Thread:1503066]
CPU: 2 PID: 1503066 Comm: VM Thread Kdump: loaded Tainted: G
Hardware name: Huawei Cloud OpenStack Nova, BIOS
RIP: 0010:console_unlock+0x343/0x540
RSP: 0000:ffffb751447db9a0 EFLAGS: 00000247 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 00000000ffffffff
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000247
RBP: ffffffffafc71f90 R08: 0000000000000000 R09: 0000000000000040
R10: 0000000000000080 R11: 0000000000000000 R12: ffffffffafc74bd0
R13: ffffffffaf60a220 R14: 0000000000000247 R15: 0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2fe6ad91f0 CR3: 00000004b2076003 CR4: 0000000000360ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 vprintk_emit+0x193/0x280
 printk+0x52/0x6e
 dump_task+0x114/0x130
 mem_cgroup_scan_tasks+0x76/0x100
 dump_header+0x1fe/0x210
 oom_kill_process+0xd1/0x100
 out_of_memory+0x125/0x570
 mem_cgroup_out_of_memory+0xb5/0xd0
 try_charge+0x720/0x770
 mem_cgroup_try_charge+0x86/0x180
 mem_cgroup_try_charge_delay+0x1c/0x40
 do_anonymous_page+0xb5/0x390
 handle_mm_fault+0xc4/0x1f0

This is because thousands of processes are in the OOM cgroup, it takes a
long time to traverse all of them.  As a result, this lead to soft lockup
in the OOM process.

To fix this issue, call 'cond_resched' in the 'mem_cgroup_scan_tasks'
function per 1000 iterations.  For global OOM, call
'touch_softlockup_watchdog' per 1000 iterations to avoid this issue.

Link: https://lkml.kernel.org/r/20241224025238.3768787-1-chenridong@huaweicloud.com
Fixes: 9cbb78bb31 ("mm, memcg: introduce own oom handler to iterate only over its own threads")
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:35 -08:00
Alex Shi
b5f469a140 mm/zsmalloc: introduce __zpdesc_clear/set_zsmalloc() 
Add helper __zpdesc_clear_zsmalloc() for __ClearPageZsmalloc(),
__zpdesc_set_zsmalloc() for __SetPageZsmalloc(), and use them in callers.

[42.hyeyoo@gmail.com: keep reset_zpdesc() to use struct page]
Link: https://lkml.kernel.org/r/20241216150450.1228021-19-42.hyeyoo@gmail.com
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:35 -08:00
Alex Shi
fc5eec0d8c mm/zsmalloc: convert get/set_first_obj_offset() to take zpdesc 
Now that all users of get/set_first_obj_offset() are converted to use
zpdesc, convert them to take zpdesc.

Link: https://lkml.kernel.org/r/20241216150450.1228021-18-42.hyeyoo@gmail.com
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:35 -08:00
Alex Shi
74999813c0 mm/zsmalloc: convert SetZsPageMovable and remove unused funcs 
Convert SetZsPageMovable() to use zpdesc, and then remove unused funcs:
get_next_page()/get_first_page()/is_first_page().

Link: https://lkml.kernel.org/r/20241216150450.1228021-17-42.hyeyoo@gmail.com
Originally-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:35 -08:00
Hyeonggon Yoo
6d0adf4b62 mm/zsmalloc: convert get_zspage() to take zpdesc 
Now that all users except get_next_page() (which will be removed in later
patch) use zpdesc, convert get_zspage() to take zpdesc instead of page.

Link: https://lkml.kernel.org/r/20241216150450.1228021-16-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:35 -08:00
Hyeonggon Yoo
65a1cf1580 mm/zsmalloc: convert migrate_zspage() to use zpdesc 
Use get_first_zpdesc/get_next_zpdesc to replace get_first/next_page. No
functional change.

Link: https://lkml.kernel.org/r/20241216150450.1228021-15-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:34 -08:00
Hyeonggon Yoo
2d57eb9ea9 mm/zsmalloc: convert location_to_obj() to take zpdesc 
As all users of location_to_obj() now use zpdesc, convert
location_to_obj() to take zpdesc.

Link: https://lkml.kernel.org/r/20241216150450.1228021-14-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:34 -08:00
Hyeonggon Yoo
7f0b0c6642 mm/zsmalloc: convert __free_zspage() to use zpdesc 
Introduce zpdesc_is_locked() and convert __free_zspage() to use zpdesc.

Link: https://lkml.kernel.org/r/20241216150450.1228021-13-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:34 -08:00
Alex Shi
73349afa00 mm/zsmalloc: convert reset_page to reset_zpdesc 
zpdesc.zspage matches with page.private, zpdesc.next matches with
page.index.  They will be reset in reset_page() which is called prior to
free base pages of a zspage.

Since the fields that need to be initialized are independent of the order
in struct zpdesc, Keep it to use struct page to ensure robustness against
potential rearrangements of struct zpdesc fields in the future.

[42.hyeyoo@gmail.com: reset zpdesc fields in reset_zpdesc()]
  Link: https://lkml.kernel.org/r/Z4Uw136VdG7vlKCL@localhost.localdomain
[42.hyeyoo@gmail.com: keep reset_zpdesc() to use struct page fields]
Link: https://lkml.kernel.org/r/20241216150450.1228021-12-42.hyeyoo@gmail.com
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:34 -08:00
Hyeonggon Yoo
6872130085 mm/zsmalloc: add two helpers for zs_page_migrate() and make it use zpdesc 
To convert page to zpdesc in zs_page_migrate(), we added
zpdesc_is_isolated()/zpdesc_zone() helpers.  No functional change.
Link: https://lkml.kernel.org/r/20241216150450.1228021-11-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:34 -08:00
Hyeonggon Yoo
4e04d10c66 mm/zsmalloc: convert obj_to_page() and zs_free() to use zpdesc 
Rename obj_to_page() to obj_to_zpdesc() and also convert it and its user
zs_free() to use zpdesc.

Link: https://lkml.kernel.org/r/20241216150450.1228021-10-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:34 -08:00
Hyeonggon Yoo
acaf41841e mm/zsmalloc: convert init_zspage() to use zpdesc 
Replace get_first/next_page func series and kmap_atomic to new helper, no
functional change.

Link: https://lkml.kernel.org/r/20241216150450.1228021-9-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:34 -08:00
Hyeonggon Yoo
76fb5d9981 mm/zsmalloc: convert obj_allocated() and related helpers to use zpdesc 
Convert obj_allocated(), and related helpers to take zpdesc.  Also make
its callers to cast (struct page *) to (struct zpdesc *) when calling
them.  The users will be converted gradually as there are many.

Link: https://lkml.kernel.org/r/20241216150450.1228021-8-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:34 -08:00
Alex Shi
7d2e1a6950 mm/zsmalloc: convert create_page_chain() and its users to use zpdesc 
Introduce a few helper functions for conversion to convert
create_page_chain() to use zpdesc, then use zpdesc in replace_sub_page().

Link: https://lkml.kernel.org/r/20241216150450.1228021-7-42.hyeyoo@gmail.com
Originally-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:33 -08:00
Hyeonggon Yoo
8f1868ad0c mm/zsmalloc: convert obj_malloc() to use zpdesc 
Use get_first_zpdesc/get_next_zpdesc to replace
get_first_page/get_next_page.  no functional change.

Link: https://lkml.kernel.org/r/20241216150450.1228021-6-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:33 -08:00
Hyeonggon Yoo
b5c1d8b510 mm/zsmalloc: add and use pfn/zpdesc seeking funcs 
Add pfn_zpdesc(), pfn_zpdesc() and kmap_local_zpdesc().  Convert
obj_to_location() to take zpdesc and also convert its users to use zpdesc.

Link: https://lkml.kernel.org/r/20241216150450.1228021-5-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:33 -08:00
Hyeonggon Yoo
4610d35c14 mm/zsmalloc: convert __zs_map_object/__zs_unmap_object to use zpdesc 
These two functions take a pointer to an array of struct page.  Make
__zs_{map,unmap}_object() take pointer to an array of zpdesc instead of
page.

Add silly type casting when calling them.  Casting will be removed later.

Link: https://lkml.kernel.org/r/20241216150450.1228021-4-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:33 -08:00
Alex Shi
c1b3bb73d5 mm/zsmalloc: use zpdesc in trylock_zspage()/lock_zspage() 
Convert trylock_zspage() and lock_zspage() to use zpdesc. To achieve
that, introduce a couple of helper functions:
  - zpdesc_lock()
  - zpdesc_unlock()
  - zpdesc_trylock()
  - zpdesc_wait_locked()
  - zpdesc_get()
  - zpdesc_put()

Here we use the folio version of functions for 2 reasons.  First,
zswap.zpool currently only uses order-0 pages and using folio could save
some compound_head checks.  Second, folio_put could bypass devmap checking
that we don't need.

BTW, thanks Intel LKP found a build warning on the patch.

Originally-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Link: https://lkml.kernel.org/r/20241216150450.1228021-3-42.hyeyoo@gmail.com
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:33 -08:00
Alex Shi
f4e33d325f mm/zsmalloc: add zpdesc memory descriptor for zswap.zpool 
Patch series "Add zpdesc memory descriptor for zswap.zpool", v9.

This patch series introduces a new memory descriptor for zswap.zpool that
currently overlaps with struct page for now.  This is part of the effort
to reduce the size of struct page and to enable dynamic allocation of
memory descriptors [1].

This series does not bloat anything for zsmalloc and no functional change
is intended (except for using zpdesc and folios).

In the near future, the removal of page->index from struct page [2] will
be addressed and the project also depends on this patch series.

Thanks to everyone got involved in this series, especially, Alex who's
been pushing it forward this year.

[1] https://lore.kernel.org/linux-mm/ZvRKzKizOfEWBtJp@casper.infradead.org
[2] https://lore.kernel.org/linux-mm/Z09hOy-UY9KC8WMb@casper.infradead.org


This patch (of 18):

The 1st patch introduces new memory descriptor zpdesc and renames
zspage.first_page to zspage.first_zpdesc, with no functional change.

We removed the comment about PG_owner_priv_1 since it is no longer used
after commit a41ec880aa ("zsmalloc: move huge compressed obj from page
to zspage").

[rdunlap@infradead.org: fix function parameter kernel-doc notation]
  Link: https://lkml.kernel.org/r/20250111063305.911010-1-rdunlap@infradead.org
[42.hyeyoo@gmail.com: rework comments a little bit]
Link: https://lkml.kernel.org/r/20241216150450.1228021-1-42.hyeyoo@gmail.com
Link: https://lkml.kernel.org/r/20241216150450.1228021-2-42.hyeyoo@gmail.com
Originally-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Alex Shi <alexs@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:33 -08:00
SeongJae Park
faa636c0ec mm/damon/sysfs-schemes: add a file for setting damos_filter->allow 
Only kernel-space DAMON API users can use inclusive DAMOS filters.  Add a
sysfs file named 'allow' under DAMOS filter directory of DAMON sysfs
interface, to let the user-space users use inclusive DAMOS filters.

Link: https://lkml.kernel.org/r/20250109175126.57878-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:32 -08:00
SeongJae Park
e2fbfedad0 mm/damon: add 'allow' argument to damos_new_filter() 
DAMON API users should set damos_filter->allow manually to use a DAMOS
allow-filter, since damos_new_filter() unsets the field always.  It is
cumbersome and easy to mistake.  Add an arugment for setting the field to
damos_new_filter().

Link: https://lkml.kernel.org/r/20250109175126.57878-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:32 -08:00
SeongJae Park
283cbc006f mm/damon/paddr: support damos_filter->allow 
Respect damos_filter->allow from 'paddr', which is a DAMON operations set
implementation for the physical address space and supports a few types of
region-internal DAMOS filters (anon, memcg and young).  The change is
similar to that of the previous commit for core layer update.

Link: https://lkml.kernel.org/r/20250109175126.57878-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:32 -08:00
SeongJae Park
491fee286e mm/damon/core: support damos_filter->allow 
DAMOS filters supports allowing behavior, but the core layer's DAMOS
filters handling logic still assumes only rejecting (filtering-out)
behavior.  Update the logic to aware of and respect the behavioral
decision by reading damos_filter->allow when making the decision to
exclude a region or not.

Link: https://lkml.kernel.org/r/20250109175126.57878-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:32 -08:00
SeongJae Park
fe6d7fdd62 mm/damon/core: add damos_filter->allow field 
DAMOS filters work as only exclusive (reject) filters.  This makes it easy
to be confused, and restrictive at combining multiple filters for covering
various types of memory.

Add a field named 'allow' to damos_filter.  The field will be used to
indicate whether the filter should work for inclusion or exclusion.  To
keep the old behavior, set it as 'false' (work as exclusive filter) by
default, from damos_new_filter().

Following two commits will make the core and operations set layers, which
handles damos_filter objects, respect the field, respectively.

Link: https://lkml.kernel.org/r/20250109175126.57878-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:31 -08:00
Luiz Capitulino
6bf9b5b40a mm: alloc_pages_bulk: rename API 
The previous commit removed the page_list argument from
alloc_pages_bulk_noprof() along with the alloc_pages_bulk_list() function.

Now that only the *_array() flavour of the API remains, we can do the
following renaming (along with the _noprof() ones):

  alloc_pages_bulk_array -> alloc_pages_bulk
  alloc_pages_bulk_array_mempolicy -> alloc_pages_bulk_mempolicy
  alloc_pages_bulk_array_node -> alloc_pages_bulk_node

Link: https://lkml.kernel.org/r/275a3bbc0be20fbe9002297d60045e67ab3d4ada.1734991165.git.luizcap@redhat.com
Signed-off-by: Luiz Capitulino <luizcap@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:31 -08:00
Luiz Capitulino
c8b979530f mm: alloc_pages_bulk_noprof: drop page_list argument 
Patch series "mm: alloc_pages_bulk: small API refactor", v2.

Today, alloc_pages_bulk_noprof() supports two arguments to return
allocated pages: a linked list and an array.  There are also higher level
APIs for both.

However, the linked list API has apparently never been used.  So, this
series removes it along with the list API and also refactors the remaining
API naming for consistency.


This patch (of 2):

commit 387ba26fb1 ("mm/page_alloc: add a bulk page allocator") added
__alloc_pages_bulk() along with the page_list argument.  The next commit
0f87d9d30f ("mm/page_alloc: add an array-based interface to the bulk
page allocator") added the array-based argument.  As it turns out, the
page_list argument has no users in the current tree (if it ever had any). 
Dropping it allows for a slight simplification and eliminates some
unnecessary checks, now that page_array is required.

Also, note that the removal of the page_list argument was proposed before
in the thread below, where Matthew Wilcox mentions that:

  """
  Iterating a linked list is _expensive_.  It is about 10x quicker to
  iterate an array than a linked list.
  """
  (https://lore.kernel.org/linux-mm/20231025093254.xvomlctwhcuerzky@techsingularity.net)

Link: https://lkml.kernel.org/r/cover.1734991165.git.luizcap@redhat.com
Link: https://lkml.kernel.org/r/f1c75db91d08cafd211eca6a3b199b629d4ffe16.1734991165.git.luizcap@redhat.com
Signed-off-by: Luiz Capitulino <luizcap@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:31 -08:00
Peter Xu
f931af2e41 mm/hugetlb: unify restore reserve accounting for new allocations 
Either hugetlb pages dequeued from hstate, or newly allocated from buddy,
would require restore-reserve accounting to be managed properly.  Merge
the two paths on it.  Add a small comment to make it slightly nicer.

Link: https://lkml.kernel.org/r/20250107204002.2683356-8-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Ackerley Tng <ackerleytng@google.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:31 -08:00
Peter Xu
72d8f72631 mm/hugetlb: drop vma_has_reserves() 
After the previous cleanup, vma_has_reserves() is mostly an empty helper
except that it says "use reserve count" is inverted meaning from "needs a
global reserve count", which is still true.

To avoid confusions on having two inverted ways to ask the same question,
always use the gbl_chg everywhere, and drop the function.

When at it, rename "chg" to "gbl_chg" in dequeue_hugetlb_folio_vma().  It
might be helpful for readers to see that the "chg" here is the global
reserve count, not the vma resv count.

Link: https://lkml.kernel.org/r/20250107204002.2683356-7-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Ackerley Tng <ackerleytng@google.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:31 -08:00
Peter Xu
51e1de00ac mm/hugetlb: simplify vma_has_reserves() 
vma_has_reserves() is a helper "trying" to know whether the vma should
consume one reservation when allocating the hugetlb folio.

However it's not clear on why we need such complexity, as such information
is already represented in the "chg" variable.

From alloc_hugetlb_folio() context, "chg" (or in the function's context,
"gbl_chg") is defined as:

  - If gbl_chg=1, the allocation cannot reuse an existing reservation
  - If gbl_chg=0, the allocation should reuse an existing reservation

Firstly, map_chg is defined as following, to cover all cases of hugetlb
reservation scenarios (mostly, via vma_needs_reservation(), but
cow_from_owner is an outlier):

CONDITION                                             HAS RESERVATION?
=========                                             ================
- SHARED: always check against per-inode resv_map
  (ignore NONRESERVE)
  - If resv exists                                ==> YES  [1]
  - If not                                        ==> NO   [2]
- PRIVATE: complicated...
  - Request came from a CoW from owner resv map   ==> NO   [3]
    (when cow_from_owner==true)
  - If does not own a resv_map at all..           ==> NO   [4]
    (examples: VM_NORESERVE, private fork())
  - If owns a resv_map, but resv donsn't exists   ==> NO   [5]
  - If owns a resv_map, and resv exists           ==> YES  [6]

Further on, gbl_chg considered spool setup, so that is a decision based on
all the context.

If we look at vma_has_reserves(), it almost does check that has already
been processed by map_chg accounting (I marked each return value to the
case above):

  static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
  {
          if (vma->vm_flags & VM_NORESERVE) {
                  if (vma->vm_flags & VM_MAYSHARE && chg == 0)
                          return true;              ==> [1]
                  else
                          return false;             ==> [2] or [4]
          }

          if (vma->vm_flags & VM_MAYSHARE) {
                  if (chg)
                          return false;             ==> [2]
                  else
                          return true;              ==> [1]
          }

          if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
                  if (chg)
                          return false;             ==> [5]
                  else
                          return true;              ==> [6]
          }

          return false;                             ==> [4]
  }

It didn't check [3], but [3] case was actually already covered now by the
"chg" / "gbl_chg" / "map_chg" calculations.

In short, vma_has_reserves() doesn't provide anything more than return
"!chg"..  so just simplify all the things.

There're a lot of comments describing truncation races, IIUC there should
have no race as long as map_chg is properly done.

Link: https://lkml.kernel.org/r/20250107204002.2683356-6-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Ackerley Tng <ackerleytng@google.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:30 -08:00
Peter Xu
923682a0dd mm/hugetlb: clean up map/global resv accounting when allocate 
alloc_hugetlb_folio() isn't a function easy to read, especially on
reservation accountings for either VMA or globally (majorly, spool only).

The 1st complexity lies in the special private CoW path, aka,
cow_from_owner=true case.

The 2nd complexity may be the confusing updates of gbl_chg after it's set
once, which looks like they can change anytime on the fly.

Logically, cow_from_user is only about vma reservation.  We could already
decouple the flag and consolidate it into map charge flag very early. 
Then we don't need to keep checking the CoW special flag every time.

This patch does it by making map_chg a tri-state flag.  Tri-state needed
is unfortunate, and it's because currently vma_needs_reservation() has a
side effect internally, that it must be followed by either a end() or
commit().

We keep the same semantic as before on one thing: "if (map_chg)" means we
need a separate per-vma resv count.  It keeps most of the old code like
before untouched with the new enum.

After this patch, we take these steps to decide these variables, hopefully
slightly easier to follow:

  - First, decide map_chg.  This will take cow_from_owner into account,
    once and for all.  It's about whether we could take a resv count from
    the vma, no matter it's shared, private, etc.

  - Then, decide gbl_chg.  The only diff here is spool, comparing to
    map_chg.

Now only update each flag once and for all, instead of keep any of them
flipping which can be very hard to follow.

With cow_from_owner merged into map_chg, we could remove quite a few such
checks all over.  Side benefit of such is that we can get rid of one more
confusing flag, which is deferred_reserve.

Cleanup the comments a bit too.  E.g., MAP_NORESERVE may not need to check
against spool limit, AFAIU, if it's on a shared mapping, and if the page
cache folio has its inode's resv map available (in which case map_chg
would have been set zero, hence the code should be correct, not the
comment).

There's one trivial detail that needs attention that this patch touched,
which is this check right after vma_commit_reservation():

  if (map_chg > map_commit)

It changes to:

  if (unlikely(map_chg == MAP_CHG_NEEDED && retval == 0))

It should behave the same like before, because previously the only way to
make "map_chg > map_commit" happen is map_chg=1 && map_commit=0.  That's
exactly the rewritten line.  Meanwhile, either commit() or end() will need
to be skipped if ENFORCE, to keep the old behavior.

Even though it looks a lot changed, but no functional change expected.

Link: https://lkml.kernel.org/r/20250107204002.2683356-5-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Ackerley Tng <ackerleytng@google.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:30 -08:00
Peter Xu
30cef82bc6 mm/hugetlb: rename avoid_reserve to cow_from_owner 
The old name "avoid_reserve" can be too generic and can be used wrongly in
the new call sites that want to allocate a hugetlb folio.

It's confusing on two things: (1) whether one can opt-in to avoid global
reservation, and (2) whether it should take more than one count.

In reality, this flag is only used in an extremely hacky path, in an
extremely hacky way in hugetlb CoW path only, and always use with 1 saying
"skip global reservation".  Rename the flag to avoid future abuse of this
flag, making it a boolean so as to reflect its true representation that
it's not a counter.  To make it even harder to abuse, add a comment above
the function to explain it.

Link: https://lkml.kernel.org/r/20250107204002.2683356-4-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Ackerley Tng <ackerleytng@google.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:30 -08:00
Peter Xu
be8d7314b1 mm/hugetlb: stop using avoid_reserve flag in fork() 
When fork() and stumble on top of a dma-pinned hugetlb private page, CoW
must happen during fork() to guarantee dma coherency.

In this specific path, hugetlb pages need to be allocated for the child
process.  Stop using avoid_reserve=1 flag here: it's not required to be
used here, as dest_vma (which is destined to be a MAP_PRIVATE hugetlb vma)
will have no private vma resv map, and that will make sure it won't be
able to use a vma reservation later.

No functional change intended with this change.  Said that, it's still
wanted to do this, so as to reduce the usage of avoid_reserve to the only
one user, which is also why this flag was introduced initially in commit
04f2cbe356 ("hugetlb: guarantee that COW faults for a process that
called mmap(MAP_PRIVATE) on hugetlbfs will succeed").  I don't see whoever
else should set it at all.

Further patch will clean up resv accounting based on this.

Link: https://lkml.kernel.org/r/20250107204002.2683356-3-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Ackerley Tng <ackerleytng@google.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:30 -08:00
Peter Xu
58db7c5fbe mm/hugetlb: fix avoid_reserve to allow taking folio from subpool 
Patch series "mm/hugetlb: Refactor hugetlb allocation resv accounting",
v2.

This is a follow up on Ackerley's series here as replacement:

https://lore.kernel.org/r/cover.1728684491.git.ackerleytng@google.com

The goal of this series is to cleanup hugetlb resv accounting, especially
during folio allocation, to decouple a few things:

  - Hugetlb folios v.s. Hugetlbfs: IOW, the hope is in the future hugetlb
    folios can be allocated completely without hugetlbfs.

  - Decouple VMA v.s. hugetlb folio allocations: allocating a hugetlb folio
    should not always require a hugetlbfs VMA.  For example, either it got
    allocated from the inode level (see hugetlbfs_fallocate() where it used
    a pesudo VMA for allocation), or it can be allocated by other kernel
    subsystems.

It paves way for other users to allocate hugetlb folios out of either
system reservations, or subpools (instead of hugetlbfs, as a file system).
For longer term, this prepares hugetlb as a separate concept versus
hugetlbfs, so that hugetlb folios can be allocated by not only hugetlbfs
and other things.

Tests I've done:

- I had a reproducer in patch 1 for the bug I found, this will start to
  work after patch 1 or the whole set applied.

- Hugetlb regression tests (on x86_64 2MBs), includes:

  - All vmtests on hugetlbfs

  - libhugetlbfs test suite (which may fail some tests, but no new failures
    will be introduced by this series, so all such failures happen before
    this series so shouldn't be relevant).


This patch (of 7):

Since commit 04f2cbe356 ("hugetlb: guarantee that COW faults for a
process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed"),
avoid_reserve was introduced for a special case of CoW on hugetlb private
mappings, and only if the owner VMA is trying to allocate yet another
hugetlb folio that is not reserved within the private vma reserved map.

Later on, in commit d85f69b0b5 ("mm/hugetlb: alloc_huge_page handle
areas hole punched by fallocate"), alloc_huge_page() enforced to not
consume any global reservation as long as avoid_reserve=true.  This
operation doesn't look correct, because even if it will enforce the
allocation to not use global reservation at all, it will still try to take
one reservation from the spool (if the subpool existed).  Then since the
spool reserved pages take from global reservation, it'll also take one
reservation globally.

Logically it can cause global reservation to go wrong.

I wrote a reproducer below, trigger this special path, and every run of
such program will cause global reservation count to increment by one, until
it hits the number of free pages:

  #define _GNU_SOURCE             /* See feature_test_macros(7) */
  #include <stdio.h>
  #include <fcntl.h>
  #include <errno.h>
  #include <unistd.h>
  #include <stdlib.h>
  #include <sys/mman.h>

  #define  MSIZE  (2UL << 20)

  int main(int argc, char *argv[])
  {
      const char *path;
      int *buf;
      int fd, ret;
      pid_t child;

      if (argc < 2) {
          printf("usage: %s <hugetlb_file>\n", argv[0]);
          return -1;
      }

      path = argv[1];

      fd = open(path, O_RDWR | O_CREAT, 0666);
      if (fd < 0) {
          perror("open failed");
          return -1;
      }

      ret = fallocate(fd, 0, 0, MSIZE);
      if (ret != 0) {
          perror("fallocate");
          return -1;
      }

      buf = mmap(NULL, MSIZE, PROT_READ|PROT_WRITE,
                 MAP_PRIVATE, fd, 0);

      if (buf == MAP_FAILED) {
          perror("mmap() failed");
          return -1;
      }

      /* Allocate a page */
      *buf = 1;

      child = fork();
      if (child == 0) {
          /* child doesn't need to do anything */
          exit(0);
      }

      /* Trigger CoW from owner */
      *buf = 2;

      munmap(buf, MSIZE);
      close(fd);
      unlink(path);

      return 0;
  }

It can only reproduce with a sub-mount when there're reserved pages on the
spool, like:

  # sysctl vm.nr_hugepages=128
  # mkdir ./hugetlb-pool
  # mount -t hugetlbfs -o min_size=8M,pagesize=2M none ./hugetlb-pool

Then run the reproducer on the mountpoint:

  # ./reproducer ./hugetlb-pool/test

Fix it by taking the reservation from spool if available.  In general,
avoid_reserve is IMHO more about "avoid vma resv map", not spool's.

I copied stable, however I have no intention for backporting if it's not a
clean cherry-pick, because private hugetlb mapping, and then fork() on top
is too rare to hit.

Link: https://lkml.kernel.org/r/20250107204002.2683356-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20250107204002.2683356-2-peterx@redhat.com
Fixes: d85f69b0b5 ("mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Tested-by: Ackerley Tng <ackerleytng@google.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Breno Leitao <leitao@debian.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:30 -08:00
Baolin Wang
1dd44c0af4 mm: shmem: skip swapcache for swapin of synchronous swap device 
With fast swap devices (such as zram), swapin latency is crucial to
applications.  For shmem swapin, similar to anonymous memory swapin, we
can skip the swapcache operation to improve swapin latency.  Testing 1G
shmem sequential swapin without THP enabled, I observed approximately a 6%
performance improvement: (Note: I repeated 5 times and took the mean data
for each test)

w/o patch	w/ patch	changes
534.8ms		501ms		+6.3%

In addition, currently, we always split the large swap entry stored in the
shmem mapping during shmem large folio swapin, which is not perfect,
especially with a fast swap device.  We should swap in the whole large
folio instead of splitting the precious large folios to take advantage of
the large folios and improve the swapin latency if the swap device is
synchronous device, which is similar to anonymous memory mTHP swapin. 
Testing 1G shmem sequential swapin with 64K mTHP and 2M mTHP, I observed
obvious performance improvement:

mTHP=64K
w/o patch	w/ patch	changes
550.4ms		169.6ms		+69%

mTHP=2M
w/o patch	w/ patch	changes
542.8ms		126.8ms		+77%

Note that skipping swapcache requires attention to concurrent swapin
scenarios.  Fortunately the swapcache_prepare() and
shmem_add_to_page_cache() can help identify concurrent swapin and large
swap entry split scenarios, and return -EEXIST for retry.

[akpm@linux-foundation.org: use IS_ENABLED(), tweak comment grammar]
Link: https://lkml.kernel.org/r/3d9f3bd3bc6ec953054baff5134f66feeaae7c1e.1736301701.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:30 -08:00
Guo Weikang
b2aad24b53 mm/memmap: prevent double scanning of memmap by kmemleak 
kmemleak explicitly scans the mem_map through the valid struct page
objects.  However, memmap_alloc() was also adding this memory to the gray
object list, causing it to be scanned twice.  Remove memmap_alloc() from
the scan list and add a comment to clarify the behavior.

Link: https://lore.kernel.org/lkml/CAOm6qn=FVeTpH54wGDFMHuCOeYtvoTx30ktnv9-w3Nh8RMofEA@mail.gmail.com/
Link: https://lkml.kernel.org/r/20250106021126.1678334-1-guoweikang.kernel@gmail.com
Signed-off-by: Guo Weikang <guoweikang.kernel@gmail.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:30 -08:00
Bruno Faccini
63db8170bf mm/fake-numa: allow later numa node hotplug 
Current fake-numa implementation prevents new Numa nodes to be later
hot-plugged by drivers.  A common symptom of this limitation is the "node
<X> was absent from the node_possible_map" message by associated warning
in mm/memory_hotplug.c: add_memory_resource().

This comes from the lack of remapping in both pxm_to_node_map[] and
node_to_pxm_map[] tables to take fake-numa nodes into account and thus
triggers collisions with original and physical nodes only-mapping that had
been determined from BIOS tables.

This patch fixes this by doing the necessary node-ids translation in both
pxm_to_node_map[]/node_to_pxm_map[] tables.  node_distance[] table has
also been fixed accordingly.


Details:

When trying to use fake-numa feature on our system where new Numa nodes
are being "hot-plugged" upon driver load, this fails with the following
type of message and warning with stack :

node 8 was absent from the node_possible_map WARNING: CPU: 61 PID: 4259 at
mm/memory_hotplug.c:1506 add_memory_resource+0x3dc/0x418

This issue prevents the use of the fake-NUMA debug feature with the
system's full configuration, when it has proven to be sometimes extremely
useful for performance testing of multi-tasked, memory-bound applications,
as it enables better isolation of processes/ranks compared to fat NUMA
nodes.

Usual numactl output after driver has “hot-plugged”/unveiled some
new Numa nodes with and without memory :
$ numactl --hardware
available: 9 nodes (0-8)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64
65 66 67 68 69 70 71
node 0 size: 490037 MB
node 0 free: 484432 MB
node 1 cpus:
node 1 size: 97280 MB
node 1 free: 97279 MB
node 2 cpus:
node 2 size: 0 MB
node 2 free: 0 MB
node 3 cpus:
node 3 size: 0 MB
node 3 free: 0 MB
node 4 cpus:
node 4 size: 0 MB
node 4 free: 0 MB
node 5 cpus:
node 5 size: 0 MB
node 5 free: 0 MB
node 6 cpus:
node 6 size: 0 MB
node 6 free: 0 MB
node 7 cpus:
node 7 size: 0 MB
node 7 free: 0 MB
node 8 cpus:
node 8 size: 0 MB
node 8 free: 0 MB
node distances:
node   0   1   2   3   4   5   6   7   8
  0:  10  80  80  80  80  80  80  80  80
  1:  80  10  255  255  255  255  255  255  255
  2:  80  255  10  255  255  255  255  255  255
  3:  80  255  255  10  255  255  255  255  255
  4:  80  255  255  255  10  255  255  255  255
  5:  80  255  255  255  255  10  255  255  255
  6:  80  255  255  255  255  255  10  255  255
  7:  80  255  255  255  255  255  255  10  255
  8:  80  255  255  255  255  255  255  255  10


With recent M.Rapoport set of fake-numa patches in mm-everything
and using numa=fake=4 boot parameter :
$ numactl --hardware
available: 4 nodes (0-3)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64
65 66 67 68 69 70 71
node 0 size: 122518 MB
node 0 free: 117141 MB
node 1 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64
65 66 67 68 69 70 71
node 1 size: 219911 MB
node 1 free: 219751 MB
node 2 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64
65 66 67 68 69 70 71
node 2 size: 122599 MB
node 2 free: 122541 MB
node 3 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64
65 66 67 68 69 70 71
node 3 size: 122479 MB
node 3 free: 122408 MB
node distances:
node   0   1   2   3
  0:  10  10  10  10
  1:  10  10  10  10
  2:  10  10  10  10
  3:  10  10  10  10


With recent M.Rapoport set of fake-numa patches in mm-everything,
this patch on top, using numa=fake=4 boot parameter :
# numactl —hardware
available: 12 nodes (0-11)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64
65 66 67 68 69 70 71
node 0 size: 122518 MB
node 0 free: 116429 MB
node 1 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64
65 66 67 68 69 70 71
node 1 size: 122631 MB
node 1 free: 122576 MB
node 2 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64
65 66 67 68 69 70 71
node 2 size: 122599 MB
node 2 free: 122544 MB
node 3 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64
65 66 67 68 69 70 71
node 3 size: 122479 MB
node 3 free: 122419 MB
node 4 cpus:
node 4 size: 97280 MB
node 4 free: 97279 MB
node 5 cpus:
node 5 size: 0 MB
node 5 free: 0 MB
node 6 cpus:
node 6 size: 0 MB
node 6 free: 0 MB
node 7 cpus:
node 7 size: 0 MB
node 7 free: 0 MB
node 8 cpus:
node 8 size: 0 MB
node 8 free: 0 MB
node 9 cpus:
node 9 size: 0 MB
node 9 free: 0 MB
node 10 cpus:
node 10 size: 0 MB
node 10 free: 0 MB
node 11 cpus:
node 11 size: 0 MB
node 11 free: 0 MB
node distances:
node   0   1   2   3   4   5   6   7   8   9  10  11
  0:  10  10  10  10  80  80  80  80  80  80  80  80
  1:  10  10  10  10  80  80  80  80  80  80  80  80
  2:  10  10  10  10  80  80  80  80  80  80  80  80
  3:  10  10  10  10  80  80  80  80  80  80  80  80
  4:  80  80  80  80  10  255  255  255  255  255  255  255
  5:  80  80  80  80  255  10  255  255  255  255  255  255
  6:  80  80  80  80  255  255  10  255  255  255  255  255
  7:  80  80  80  80  255  255  255  10  255  255  255  255
  8:  80  80  80  80  255  255  255  255  10  255  255  255
  9:  80  80  80  80  255  255  255  255  255  10  255  255
 10:  80  80  80  80  255  255  255  255  255  255  10  255
 11:  80  80  80  80  255  255  255  255  255  255  255  10

Link: https://lkml.kernel.org/r/20250106120659.359610-2-bfaccini@nvidia.com
Signed-off-by: Bruno Faccini <bfaccini@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:29 -08:00
SeongJae Park
5ec4333b19 mm/damon: remove DAMON debugfs interface 
It's time to remove DAMON debugfs interface, which has deprecated long
before in February 2023.  Read the cover letter of this patch series for
more details.

All documents and related tests are also removed.  Finally remove the
interface.

Link: https://lkml.kernel.org/r/20250106191941.107070-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Alex Shi <alexs@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Hu Haowen <2023002089@link.tyut.edu.cn>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Rae Moar <rmoar@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yanteng Si <si.yanteng@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:29 -08:00
SeongJae Park
4d047d4f8a mm/damon: remove DAMON debugfs interface kunit tests 
It's time to remove DAMON debugfs interface, which has deprecated long
before in February 2023.  Read the cover letter of this patch series for
more details.

Remove kunit tests for the interface, to prevent unnecessary test
failures.

Link: https://lkml.kernel.org/r/20250106191941.107070-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Alex Shi <alexs@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Hu Haowen <2023002089@link.tyut.edu.cn>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Rae Moar <rmoar@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yanteng Si <si.yanteng@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:29 -08:00
SeongJae Park
a2a60f9e57 mm/damon/sysfs-schemes: expose per-region filter-passed bytes 
Per-region operations set-handled DAMOS filters passed memory size
information is provided to only DAMON core API users.  Further expose it
to the user space by adding a new DAMON sysfs interface file under each
scheme tried region directory.

Link: https://lkml.kernel.org/r/20250106193401.109161-14-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:28 -08:00
SeongJae Park
cfc33a7d2d mm/damon/core: pass per-region filter-passed bytes to damos_walk_control->walk_fn() 
Total size of memory that passed DAMON operations set layer-handled DAMOS
filters per scheme is provided to DAMON core API and ABI (sysfs interface)
users.  Having it per-region in non-accumulated way can provide it in
finer granularity.  Provide it to damos_walk() core API users, by passing
the data to damos_walk_control->walk_fn().

Link: https://lkml.kernel.org/r/20250106193401.109161-13-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:28 -08:00
SeongJae Park
9caac9d55f mm/damon/syfs-schemes: implement per-scheme filter-passed bytes stat 
Add a new DAMON sysfs interface file under scheme stat directory, namely
'sz_ops_filter_passed'.  It represents total bytes that passed
region-internal DAMOS filters of the scheme that handled by the DAMON
operations set layer.

Link: https://lkml.kernel.org/r/20250106193401.109161-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:27 -08:00
SeongJae Park
60fa9355a6 mm/damon/core: implement per-scheme ops-handled filter-passed bytes stat 
Implement a new per-DAMOS scheme statistic field, namely
sz_ops_filter_passed, using the changed damon_operations->apply_scheme()
interface.  It counts total bytes of memory that given DAMOS action tried
to be applied, and passed the operations layer handled region-internal
filters of the scheme.  DAMON API users can access it using DAMON-internal
safe access features such as damon_call() and/or damos_walk().

Link: https://lkml.kernel.org/r/20250106193401.109161-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:27 -08:00
SeongJae Park
c0cb9d91bf mm/damon/paddr: report filter-passed bytes back for DAMOS_STAT action 
DAMOS_STAT action handling of paddr DAMON operations set implementation is
simply ignoring the region-internal DAMOS filters, and therefore not
reporting back the filter-passed bytes.  Apply the filters and report back
the information.

Before this change, DAMOS_STAT was doing nothing for DAMOS filters.  Hence
users might see some performance regressions.  Such regression for use
cases where no region-internal DAMOS filter is added to the scheme will be
negligible, since this change avoids unnecessary filtering works if no
such filter is installed.

For old users who are using DAMOS_STAT with the types of filters, the
regression could be visible depending on the size of the region and the
overhead of the installed DAMOS filters.  But, because the filters were
completely ignored before in the use case, no real users would really
depend on such use case that makes no point.

Link: https://lkml.kernel.org/r/20250106193401.109161-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:27 -08:00
SeongJae Park
96f1971dab mm/damon/paddr: report filter-passed bytes back for normal actions 
damon_operations->apply_scheme() implementations are requested to report
back how many bytes of the given region has passed DAMOS filter.  'paddr'
operations set implementation supports some of region-internal DAMOS
filter handling for normal DAMOS actions except DAMOS_STAT action.  But,
those are not respecting the request.  Report the region-internal DAMOS
filter-passed bytes back for the actions.

Link: https://lkml.kernel.org/r/20250106193401.109161-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:27 -08:00
SeongJae Park
b5bbe9c08f mm/damon: ask apply_scheme() to report filter-passed region-internal bytes 
Some DAMOS filter types including those for young page, anon page, and
belonging memcg are handled by underlying DAMON operations set
implementation, via damon_operations->apply_scheme() interface.  How many
bytes of the region have passed the filter can be useful for DAMOS scheme
tuning and access pattern monitoring.  Modify the interface to let the
callback implementation reports back the number if possible.

Link: https://lkml.kernel.org/r/20250106193401.109161-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:26 -08:00
SeongJae Park
ee14cbc6f8 mm/damon/sysfs: remove unused code for schemes tried regions update 
DAMON sysfs interface was using damon_callback with its own complicated
synchronization logics to update DAMOS scheme applied regions directories
and files.  But it is replaced to use damos_walk(), and the additional
synchronization logics are no more being used.  Remove those.

Link: https://lkml.kernel.org/r/20250103174400.54890-11-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:26 -08:00
SeongJae Park
66178e4ec3 mm/damon/sysfs: use damos_walk() for update_schemes_tried_{bytes,regions} 
DAMON sysfs interface uses damon_callback with its own complicated
synchronization facility to handle update_schemes_tried_bytes and
update_schemes_tried_regions commands.  But damos_walk() can support the
use case without the additional synchronizations.  Convert the code to use
damos_walk() instead.

Link: https://lkml.kernel.org/r/20250103174400.54890-10-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:26 -08:00
SeongJae Park
bf0eaba0ff mm/damon/core: implement damos_walk() 
Introduce a new core layer interface, damos_walk().  It aims to replace
some damon_callback usages that access DAMOS schemes applied regions of
ongoing kdamond with additional synchronizations.  It receives a function
pointer and asks kdamond to invoke it for any region that it tried to
apply any DAMOS action within one scheme apply interval for every scheme
of it.  The function further waits until the kdamond finishes the
invocations for every scheme, or cancels the request, and returns.

The kdamond invokes the function as requested within the main loop.  If it
is deactivated by DAMOS watermarks or going out of the main loop, it marks
the request as canceled, so that damos_walk() can wakeup and return.

Link: https://lkml.kernel.org/r/20250103174400.54890-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:25 -08:00
SeongJae Park
9a5aa3349b mm/damon/sysfs: use damon_call() for update_schemes_effective_quotas 
DAMON sysfs interface uses damon_callback with its own synchronization
facility to handle update_schemes_effective_quotas command.  But
damon_call() can support the use case without the additional
synchronizations.  Convert the code to use damon_call() instead.

Link: https://lkml.kernel.org/r/20250103174400.54890-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:25 -08:00
SeongJae Park
60d2c527bd mm/damon/sysfs: use damon_call() for commit_schemes_quota_goals 
DAMON sysfs interface uses damon_callback with its own synchronization
facility to handle commit_schemes_quota_goals command.  But damon_call()
can support the use case without the additional synchronizations.  Convert
the code to use damon_call() instead.

Link: https://lkml.kernel.org/r/20250103174400.54890-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:25 -08:00
SeongJae Park
f64539dcdb mm/damon/sysfs: use damon_call() for update_schemes_stats 
DAMON sysfs interface uses damon_callback with its own synchronization
facility to handle update_schemes_stats kdamond command.  But damon_call()
can support the use case without the additional synchronizations.  Convert
the code to use damon_call() instead.

Link: https://lkml.kernel.org/r/20250103174400.54890-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:25 -08:00
SeongJae Park
42b7491af1 mm/damon/core: introduce damon_call() 
Introduce a new DAMON core API function, damon_call().  It aims to replace
some damon_callback usages that access damon_ctx of ongoing kdamond with
additional synchronizations.  It receives a function pointer, let the
parallel kdamond invokes the function, and returns after the invocation is
finished, or canceled due to some races.

kdamond invokes the function inside the main loop after sampling is done. 
If it is deactivated by DAMOS watermarks or already out of the main loop,
mark the request as canceled so that damon_call() can wakeup and return.

Link: https://lkml.kernel.org/r/20250103174400.54890-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:25 -08:00
SeongJae Park
0f3e40eb5e mm/damon/sysfs: handle clear_schemes_tried_regions from DAMON sysfs context 
DAMON sysfs interface handles clear_schemes_tried_regions request from the
DAMON callback context (damon_sysfs_cmd_request_callback()), which is
designed to be used for safe access to the related DAMON context internal
data.  But no DAMON context internal data is accessed for the work. 
Directly handle it from DAMON sysfs interface context, namely
damon_sysfs_handle_cmd().

Link: https://lkml.kernel.org/r/20250103174400.54890-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:25 -08:00
SeongJae Park
e035320fd3 mm/damon/sysfs-schemes: remove unnecessary schemes existence check in damon_sysfs_schemes_clear_regions() 
Patch series "mm/damon: replace most damon_callback usages in sysfs with
new core functions".

DAMON provides damon_callback API that notifies monitoring events and
allows safe access to damon_ctx internal data.  The usage is simple. 
Users register and deregister callback functions for different monitoring
events in damon_ctx.  Then the DAMON worker thread (kdamond) of the
damon_ctx calls back the registered functions on the events.

It is designed in such simple way because it was sufficient for usages of
DAMON at the early days.  We also wanted to make it flexible so that API
user code can implement any required additional features on top of
damon_callback on their demands.

As expected, more sophisticated usages have invented.  Online updates of
DAMON parameters and DAMOS auto-tuning inputs, and online retrieval of
DAMOS statistics and tried regions information are such usages.  Because
damon_callback doesn't provide any explicit synchronization mechanism, the
user ABIs for exposing such functionalities are implemented in
asynchronous ways (DAMON_RECLAIM and DAMON_LRU_SORT}), or synchronous ways
(DAMON_SYSFS) with additional synchronization mechanisms that built inside
the ABI implementation, on top of damon_callback.

So damon_callback is working as expected.  However, the additional
mechanisms built inside ABI on top of damon_callback is becoming somewhat
too big and not easy to maintain.  The additional mechanisms can be
smaller and easier to maintain when implemented inside the core logic
layer.

Introduce two new DAMON core API, namely 'damon_call()' and
'damos_walk()'.  The two functions support synchronous access to
- damon_ctx internal data including DAMON parameters and monitoring
  results, and
- DAMOS-specific data such as regions that each DAMOS action is applied,
respectively.

And replace most of damon_callback usages in DAMON sysfs interface with
the new core API functions.  damon_callback usage for online DAMON
parameters tuning is not replaced in this series, since it has specific
callback timing assumptions that require more works.

Patch sequence
==============

First two patches are fixups for simplifying the following changes.  Those
remove a unnecessary condition check and a synchronization, respectively.

Third patch implements one of the new DAMON core APIs, namely
damon_call().  Three patches replacing damon_callback usages in DAMON
sysfs interface using damon_call() follow.

Then, seventh and eighth patches introduces the other new DAMON API,
damos_walk(), and document it on the design doc.  Ninth patch replaces two
damon_callback usages in DAMON sysfs interface using damos_walk().

The tenth patch finally cleans up code that no more being used.


This patch (of 10):

damon_sysfs_schemes_clear_regions() skips removing the scheme tried region
directories only if the matching scheme is still ongoing.  It is
unnecessary check, since what users want is just removing the entire
region directories.  Remove the unnecessary check.

Link: https://lkml.kernel.org/r/20250103174400.54890-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250103174400.54890-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:25 -08:00
Lorenzo Stoakes
fe1679ed02 mm/debug: prefer VM_WARN_ON_VMG() to report VMG debug warnings 
Now we have VM_WARN_ON_VMG() to provide us with considerably more debug
output when a debug assert fails, utilise it everywhere we can.

This allows us to have considerably more information to go on when things
go wrong, especially when a non-repro issue occurs as reported by
syzkaller or the like.

Link: https://lkml.kernel.org/r/986e45e9549e71284ac7a7fa878688568a94d58b.1735932169.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:24 -08:00
Lorenzo Stoakes
b0d66d82fc mm/debug: introduce VM_WARN_ON_VMG() to dump VMA merge state 
Patch series "mm/debug: introduce and use VM_WARN_ON_VMG()".

We use a number of asserts, enabled only when CONFIG_DEBUG_VM is set,
during VMA merge operations to ensure state is as expected.

However, when syzkaller or the like encounters these asserts, often the
information provided by the report is insufficient to narrow down what the
problem is.

We noticed this recently in [0], where a non-repro issue resisted
debugging due to simply not having sufficient information to go on.

This series improves the situation by providing VM_WARN_ON_VMG() which
acts like VM_WARN_ON() (i.e.  only actually being invoked if
CONFIG_DEBUG_VM is set), while dumping significant information about the
VMA merge state, the mm_struct describing the virtual address space, all
associated VMAs and, if CONFIG_DEBUG_VM_MAPLE_TREE is set, the associated
maple tree.

[0]:https://lore.kernel.org/all/6774c98f.050a0220.25abdd.0991.GAE@google.com/


This patch (of 2):

We use a number of asserts, enabled only when CONFIG_DEBUG_VM is set,
during VMA merge operations to ensure state is as expected.

However, when syzkaller or the like encounters these asserts, often the
information provided by the report is insufficient to narrow down what the
problem is.

This might not be so much of an issue if the reported problem is
reproducible, but if it is a rarely encountered race or some other case
which precludes a repro, it is a very big problem (see [0] for the
motivating case).

It is therefore sensible to provide a means by which we can easily and
conveniently dump a lot more information in these circumstances.

The aggregation of merge state into a single struct threaded through the
operation makes this trivial - we can simply introduce a variant on
VM_WARN_ON() which takes the VMA merge state object (vmg) and use that to
dump information.

This patch therefore introduces VM_WARN_ON_VMG() which provides this
functionality.

It additionally dumps full mm state, VMA state for each of the three VMAs
the vmg contains (prev, next, vma) and if CONFIG_DEBUG_VM_MAPLE_TREE is
enabled, dumps the maple tree from the provided VMA iterator if non-NULL.

This patch has no functional impact if CONFIG_DEBUG_VM is not set.

[0]:https://lore.kernel.org/all/6774c98f.050a0220.25abdd.0991.GAE@google.com/

Link: https://lkml.kernel.org/r/cover.1735932169.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/13b09b52d4d103ee86acaf0ae612539648ae29e0.1735932169.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:23 -08:00
Qi Zheng
e74e173101 mm: pgtable: move __tlb_remove_table_one() in x86 to generic file 
The __tlb_remove_table_one() in x86 does not contain architecture-specific
content, so move it to the generic file.

Link: https://lkml.kernel.org/r/aab8a449bc67167943fd2cb5aab0a3a23b7b1cd7.1736317725.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:23 -08:00
Qi Zheng
db6b435d73 mm: pgtable: introduce pagetable_dtor() 
The pagetable_p*_dtor() are exactly the same except for the handling of
ptlock.  If we make ptlock_free() handle the case where ptdesc->ptl is
NULL and remove VM_BUG_ON_PAGE() from pmd_ptlock_free(), we can unify
pagetable_p*_dtor() into one function.  Let's introduce pagetable_dtor()
to do this.

Later, pagetable_dtor() will be moved to tlb_remove_ptdesc(), so that
ptlock and page table pages can be freed together (regardless of whether
RCU is used).  This prevents the use-after-free problem where the ptlock
is freed immediately but the page table pages is freed later via RCU.

Link: https://lkml.kernel.org/r/47f44fff9dc68d9d9e9a0d6c036df275f820598a.1736317725.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Originally-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>	[s390]
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:22 -08:00
Rik van Riel
1aa43598c0 mm: remove unnecessary calls to lru_add_drain 
There seem to be several categories of calls to lru_add_drain and
lru_add_drain_all.

The first are code paths that recently allocated, swapped in, or otherwise
processed a batch of pages, and want them all on the LRU.  These drain
pages that were recently allocated, probably on the local CPU.

A second category are code paths that are actively trying to reclaim,
migrate, or offline memory.  These often use lru_add_drain_all, to drain
the caches on all CPUs.

However, there also seem to be some other callers where we aren't really
doing either.  They are calling lru_add_drain(), despite operating on
pages that may have been allocated long ago, and quite possibly on
different CPUs.

Those calls are not likely to be effective at anything but creating lock
contention on the LRU locks.

Remove the lru_add_drain calls in the latter category.

For detailed reasoning, see [1] and [2].

Link: https://lkml.kernel.org/r/dca2824e8e88e826c6b260a831d79089b5b9c79d.camel@surriel.com [1]
Link: https://lkml.kernel.org/r/xxfhcjaq2xxcl5adastz5omkytenq7izo2e5f4q7e3ns4z6lko@odigjjc7hqrg [2]
Link: https://lkml.kernel.org/r/20241219153253.3da9e8aa@fangorn
Signed-off-by: Rik van Riel <riel@surriel.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:21 -08:00
Gregory Price
44d46b76c3 mm: add build-time option for hotplug memory default online type 
Memory hotplug presently auto-onlines memory into a zone the kernel deems
appropriate if CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y.

The memhp_default_state boot param enables runtime config, but it's not
possible to do this at build-time.

Remove CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE, and replace it with
CONFIG_MHP_DEFAULT_ONLINE_TYPE_* choices that sync with the boot param.

Selections:
  CONFIG_MHP_DEFAULT_ONLINE_TYPE_OFFLINE
    => mhp_default_online_type = "offline"
       Memory will not be onlined automatically.

  CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO
    => mhp_default_online_type = "online"
       Memory will be onlined automatically in a zone deemed.
       appropriate by the kernel.

  CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_KERNEL
    => mhp_default_online_type = "online_kernel"
       Memory will be onlined automatically.
       The zone may allow kernel data (e.g. ZONE_NORMAL).

  CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_MOVABLE
    => mhp_default_online_type = "online_movable"
       Memory will be onlined automatically.
       The zone will be ZONE_MOVABLE.

Default to CONFIG_MHP_DEFAULT_ONLINE_TYPE_OFFLINE to match the existing
default CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=n behavior.

Existing users of CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y should use
CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO.

[gourry@gourry.net: update KConfig comments]
  Link: https://lkml.kernel.org/r/20241226182918.648799-1-gourry@gourry.net
Link: https://lkml.kernel.org/r/20241220210709.300066-1-gourry@gourry.net
Signed-off-by: Gregory Price <gourry@gourry.net>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:21 -08:00
yangge
04f13d241b mm: replace free hugepage folios after migration 
My machine has 4 NUMA nodes, each equipped with 32GB of memory.  I have
configured each NUMA node with 16GB of CMA and 16GB of in-use hugetlb
pages.  The allocation of contiguous memory via cma_alloc() can fail
probabilistically.

When there are free hugetlb folios in the hugetlb pool, during the
migration of in-use hugetlb folios, new folios are allocated from the free
hugetlb pool.  After the migration is completed, the old folios are
released back to the free hugetlb pool instead of being returned to the
buddy system.  This can cause test_pages_isolated() check to fail,
ultimately leading to the failure of cma_alloc().

Call trace:

cma_alloc()
    __alloc_contig_migrate_range() // migrate in-use hugepage
    test_pages_isolated()
        __test_page_isolated_in_pageblock()
             PageBuddy(page) // check if the page is in buddy

To address this issue, we introduce a function named
replace_free_hugepage_folios().  This function will replace the hugepage
in the free hugepage pool with a new one and release the old one to the
buddy system.  After the migration of in-use hugetlb pages is completed,
we will invoke replace_free_hugepage_folios() to ensure that these
hugepages are properly released to the buddy system.  Following this step,
when test_pages_isolated() is executed for inspection, it will
successfully pass.

Additionally, when alloc_contig_range() is used to migrate multiple in-use
hugetlb pages, it can result in some in-use hugetlb pages being released
back to the free hugetlb pool and subsequently being reallocated and used
again.  For example:

[huge 0] [huge 1]

To migrate huge 0, we obtain huge x from the pool.  After the migration is
completed, we return the now-freed huge 0 back to the pool.  When it's
time to migrate huge 1, we can simply reuse the now-freed huge 0 from the
pool.  As a result, when replace_free_hugepage_folios() is executed, it
cannot release huge 0 back to the buddy system.  To address this issue, we
should prevent the reuse of isolated free hugepages during the migration
process.

Link: https://lkml.kernel.org/r/1734503588-16254-1-git-send-email-yangge1116@126.com
Link: https://lkml.kernel.org/r/1736582300-11364-1-git-send-email-yangge1116@126.com
Signed-off-by: yangge <yangge1116@126.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:20 -08:00
Kairui Song
6769183166 mm/swap_cgroup: decouple swap cgroup recording and clearing 
The current implementation of swap cgroup tracking is a bit complex and
fragile:

On charging path, swap_cgroup_record always records an actual memcg id,
and it depends on the caller to make sure all entries passed in must
belong to one single folio.  As folios are always charged or uncharged as
a whole, and always charged and uncharged in order, swap_cgroup doesn't
need an extra lock.

On uncharging path, swap_cgroup_record always sets the record to zero. 
These entries won't be charged again until uncharging is done.  So there
is no extra lock needed either.  Worth noting that swap cgroup clearing
may happen without folio involved, eg.  exiting processes will zap its
page table without swapin.

The xchg/cmpxchg provides atomic operations and barriers to ensure no
tearing or synchronization issue of these swap cgroup records.

It works but quite error-prone.  Things can be much clear and robust by
decoupling recording and clearing into two helpers.  Recording takes the
actual folio being charged as argument, and clearing always set the record
to zero, and refine the debug sanity checks to better reflect their usage

Benchmark even showed a very slight improvement as it saved some
extra arguments and lookups:

make -j96 with defconfig on tmpfs in 1.5G memory cgroup using 4k folios:
Before: sys 9617.23 (stdev 37.764062)
After : sys 9541.54 (stdev 42.973976)

make -j96 with defconfig on tmpfs in 2G memory cgroup using 64k folios:
Before: sys 7358.98 (stdev 54.927593)
After : sys 7337.82 (stdev 39.398956)

Link: https://lkml.kernel.org/r/20241218114633.85196-5-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Suggested-by: Chris Li <chrisl@kernel.org>
Cc: Barry Song <baohua@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:19 -08:00
Kairui Song
2b3a58b121 mm/swap_cgroup: remove global swap cgroup lock 
commit e9e58a4ec3 ("memcg: avoid use cmpxchg in swap cgroup
maintainance") replaced the cmpxchg/xchg with a global irq spinlock
because some archs doesn't support 2 bytes cmpxchg/xchg.  Clearly this
won't scale well.

And as commented in swap_cgroup.c, this lock is not needed for map
synchronization.

Emulation of 2 bytes xchg with atomic cmpxchg isn't hard, so implement it
to get rid of this lock.  Introduced two helpers for doing so and they can
be easily dropped if a generic 2 byte xchg is support.

Testing using 64G brd and build with build kernel with make -j96 in 1.5G
memory cgroup using 4k folios showed below improvement (6 test run):

Before this series:
Sys time: 10782.29 (stdev 42.353886)
Real time: 171.49 (stdev 0.595541)

After this commit:
Sys time: 9617.23 (stdev 37.764062), -10.81%
Real time: 159.65 (stdev 0.587388), -6.90%

With 64k folios and 2G memcg:
Before this series:
Sys time: 8176.94 (stdev 26.414712)
Real time: 141.98 (stdev 0.797382)

After this commit:
Sys time: 7358.98 (stdev 54.927593), -10.00%
Real time: 134.07 (stdev 0.757463), -5.57%

Sequential swapout of 8G 64k zero folios with madvise (24 test run):
Before this series:
5461409.12 us (stdev 183957.827084)

After this commit:
5420447.26 us (stdev 196419.240317)

Sequential swapin of 8G 4k zero folios (24 test run):
Before this series:
19736958.916667 us (stdev 189027.246676)

After this commit:
19662182.629630 us (stdev 172717.640614)

Performance is better or at least not worse for all tests above.

Link: https://lkml.kernel.org/r/20241218114633.85196-4-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:19 -08:00
Kairui Song
40733e7e0c mm/swap_cgroup: remove swap_cgroup_cmpxchg 
This function is never used after commit 6b611388b6 ("memcg-v1: remove
charge move code").

Link: https://lkml.kernel.org/r/20241218114633.85196-3-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Barry Song <baohua@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:19 -08:00
Kairui Song
a53f311349 mm, memcontrol: avoid duplicated memcg enable check 
Patch series "mm/swap_cgroup: remove global swap cgroup lock", v3.

This series removes the global swap cgroup lock.  The critical section of
this lock is very short but it's still a bottle neck for mass parallel
swap workloads.

Up to 10% performance gain for tmpfs build kernel test on a 48c96t system
under memory pressure, and no regression for other cases:


This patch (of 3):

mem_cgroup_uncharge_swap() includes a mem_cgroup_disabled() check,
so the caller doesn't need to check that.

Link: https://lkml.kernel.org/r/20241218114633.85196-1-ryncsn@gmail.com
Link: https://lkml.kernel.org/r/20241218114633.85196-2-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Barry Song <baohua@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:19 -08:00
Thomas Weißschuh
e2c9e6190d mm/page_idle: constify 'struct bin_attribute' 
The sysfs core now allows instances of 'struct bin_attribute' to be moved
into read-only memory.  Make use of that to protect them against
accidental or malicious modifications.

Link: https://lkml.kernel.org/r/20241216-sysfs-const-bin_attr-page_idle-v1-1-cc01ecc55196@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:19 -08:00
Andrew Morton
1fc1065355 mm/huge_memory.c: rename shadowed local 
split_huge_pages_write() has a lccal `buf' which shadows incoming arg
`buf'.  Reviewer confusion resulted.  Rename the inner local to `tok_buf'.

Cc: Leo Stone <leocstone@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:18 -08:00
Christoph Hellwig
ec838c7da5 mm: unexport apply_to_existing_page_range 
apply_to_existing_page_range() is only used by non-modular code.

Link: https://lkml.kernel.org/r/20241212073423.1439954-1-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:18 -08:00
Jinliang Zheng
8e6173ccf7 mm: fix outdated incorrect code comments for handle_mm_fault() 
[akpm@linux-foundation.org: s/mmap_Lock/mmap_lock/, per Liam]
Link: https://lkml.kernel.org/r/20241213031820.778342-1-alexjlzheng@tencent.com
Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:18 -08:00
Linus Torvalds
8883957b3c \n 
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Merge tag 'fsnotify_hsm_for_v6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

Pull fsnotify pre-content notification support from Jan Kara:
 "This introduces a new fsnotify event (FS_PRE_ACCESS) that gets
  generated before a file contents is accessed.

  The event is synchronous so if there is listener for this event, the
  kernel waits for reply. On success the execution continues as usual,
  on failure we propagate the error to userspace. This allows userspace
  to fill in file content on demand from slow storage. The context in
  which the events are generated has been picked so that we don't hold
  any locks and thus there's no risk of a deadlock for the userspace
  handler.

  The new pre-content event is available only for users with global
  CAP_SYS_ADMIN capability (similarly to other parts of fanotify
  functionality) and it is an administrator responsibility to make sure
  the userspace event handler doesn't do stupid stuff that can DoS the
  system.

  Based on your feedback from the last submission, fsnotify code has
  been improved and now file->f_mode encodes whether pre-content event
  needs to be generated for the file so the fast path when nobody wants
  pre-content event for the file just grows the additional file->f_mode
  check. As a bonus this also removes the checks whether the old
  FS_ACCESS event needs to be generated from the fast path. Also the
  place where the event is generated during page fault has been moved so
  now filemap_fault() generates the event if and only if there is no
  uptodate folio in the page cache.

  Also we have dropped FS_PRE_MODIFY event as current real-world users
  of the pre-content functionality don't really use it so let's start
  with the minimal useful feature set"

* tag 'fsnotify_hsm_for_v6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: (21 commits)
  fanotify: Fix crash in fanotify_init(2)
  fs: don't block write during exec on pre-content watched files
  fs: enable pre-content events on supported file systems
  ext4: add pre-content fsnotify hook for DAX faults
  btrfs: disable defrag on pre-content watched files
  xfs: add pre-content fsnotify hook for DAX faults
  fsnotify: generate pre-content permission event on page fault
  mm: don't allow huge faults for files with pre content watches
  fanotify: disable readahead if we have pre-content watches
  fanotify: allow to set errno in FAN_DENY permission response
  fanotify: report file range info with pre-content events
  fanotify: introduce FAN_PRE_ACCESS permission event
  fsnotify: generate pre-content permission event on truncate
  fsnotify: pass optional file access range in pre-content event
  fsnotify: introduce pre-content permission events
  fanotify: reserve event bit of deprecated FAN_DIR_MODIFY
  fanotify: rename a misnamed constant
  fanotify: don't skip extra event info if no info_mode is set
  fsnotify: check if file is actually being watched for pre-content events on open
  fsnotify: opt-in for permission events at file open time
  ...
 2025-01-23 13:36:06 -08:00
Linus Torvalds
5f537664e7 cachestat: fix page cache statistics permission checking 
When the 'cachestat()' system call was added in commit cf264e1329
("cachestat: implement cachestat syscall"), it was meant to be a much
more convenient (and performant) version of mincore() that didn't need
mapping things into the user virtual address space in order to work.

But it ended up missing the "check for writability or ownership" fix for
mincore(), done in commit 134fca9063 ("mm/mincore.c: make mincore()
more conservative").

This just adds equivalent logic to 'cachestat()', modified for the file
context (rather than vma).

Reported-by: Sudheendra Raghav Neela <sneela@tugraz.at>
Fixes: cf264e1329 ("cachestat: implement cachestat syscall")
Tested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2025-01-21 20:30:19 -08:00
Linus Torvalds
1d6d399223 Kthreads affinity follow either of 4 existing different patterns: 
1) Per-CPU kthreads must stay affine to a single CPU and never execute
    relevant code on any other CPU. This is currently handled by smpboot
    code which takes care of CPU-hotplug operations. Affinity here is
    a correctness constraint.
 
 2) Some kthreads _have_ to be affine to a specific set of CPUs and can't
    run anywhere else. The affinity is set through kthread_bind_mask()
    and the subsystem takes care by itself to handle CPU-hotplug
    operations. Affinity here is assumed to be a correctness constraint.
 
 3) Per-node kthreads _prefer_ to be affine to a specific NUMA node. This
    is not a correctness constraint but merely a preference in terms of
    memory locality. kswapd and kcompactd both fall into this category.
    The affinity is set manually like for any other task and CPU-hotplug
    is supposed to be handled by the relevant subsystem so that the task
    is properly reaffined whenever a given CPU from the node comes up.
    Also care should be taken so that the node affinity doesn't cross
    isolated (nohz_full) cpumask boundaries.
 
 4) Similar to the previous point except kthreads have a _preferred_
    affinity different than a node. Both RCU boost kthreads and RCU
    exp kworkers fall into this category as they refer to "RCU nodes"
    from a distinctly distributed tree.
 
 Currently the preferred affinity patterns (3 and 4) have at least 4
 identified users, with more or less success when it comes to handle
 CPU-hotplug operations and CPU isolation. Each of which do it in its own
 ad-hoc way.
 
 This is an infrastructure proposal to handle this with the following API
 changes:
 
 _ kthread_create_on_node() automatically affines the created kthread to
   its target node unless it has been set as per-cpu or bound with
   kthread_bind[_mask]() before the first wake-up.
 
 - kthread_affine_preferred() is a new function that can be called right
   after kthread_create_on_node() to specify a preferred affinity
   different than the specified node.
 
 When the preferred affinity can't be applied because the possible
 targets are offline or isolated (nohz_full), the kthread is affine
 to the housekeeping CPUs (which means to all online CPUs most of the
 time or only the non-nohz_full CPUs when nohz_full= is set).
 
 kswapd, kcompactd, RCU boost kthreads and RCU exp kworkers have been
 converted, along with a few old drivers.
 
 Summary of the changes:
 
 * Consolidate a bunch of ad-hoc implementations of kthread_run_on_cpu()
 
 * Introduce task_cpu_fallback_mask() that defines the default last
   resort affinity of a task to become nohz_full aware
 
 * Add some correctness check to ensure kthread_bind() is always called
   before the first kthread wake up.
 
 * Default affine kthread to its preferred node.
 
 * Convert kswapd / kcompactd and remove their halfway working ad-hoc
   affinity implementation
 
 * Implement kthreads preferred affinity
 
 * Unify kthread worker and kthread API's style
 
 * Convert RCU kthreads to the new API and remove the ad-hoc affinity
   implementation.
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Merge tag 'kthread-for-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks

Pull kthread updates from Frederic Weisbecker:
 "Kthreads affinity follow either of 4 existing different patterns:

   1) Per-CPU kthreads must stay affine to a single CPU and never
      execute relevant code on any other CPU. This is currently handled
      by smpboot code which takes care of CPU-hotplug operations.
      Affinity here is a correctness constraint.

   2) Some kthreads _have_ to be affine to a specific set of CPUs and
      can't run anywhere else. The affinity is set through
      kthread_bind_mask() and the subsystem takes care by itself to
      handle CPU-hotplug operations. Affinity here is assumed to be a
      correctness constraint.

   3) Per-node kthreads _prefer_ to be affine to a specific NUMA node.
      This is not a correctness constraint but merely a preference in
      terms of memory locality. kswapd and kcompactd both fall into this
      category. The affinity is set manually like for any other task and
      CPU-hotplug is supposed to be handled by the relevant subsystem so
      that the task is properly reaffined whenever a given CPU from the
      node comes up. Also care should be taken so that the node affinity
      doesn't cross isolated (nohz_full) cpumask boundaries.

   4) Similar to the previous point except kthreads have a _preferred_
      affinity different than a node. Both RCU boost kthreads and RCU
      exp kworkers fall into this category as they refer to "RCU nodes"
      from a distinctly distributed tree.

  Currently the preferred affinity patterns (3 and 4) have at least 4
  identified users, with more or less success when it comes to handle
  CPU-hotplug operations and CPU isolation. Each of which do it in its
  own ad-hoc way.

  This is an infrastructure proposal to handle this with the following
  API changes:

   - kthread_create_on_node() automatically affines the created kthread
     to its target node unless it has been set as per-cpu or bound with
     kthread_bind[_mask]() before the first wake-up.

   - kthread_affine_preferred() is a new function that can be called
     right after kthread_create_on_node() to specify a preferred
     affinity different than the specified node.

  When the preferred affinity can't be applied because the possible
  targets are offline or isolated (nohz_full), the kthread is affine to
  the housekeeping CPUs (which means to all online CPUs most of the time
  or only the non-nohz_full CPUs when nohz_full= is set).

  kswapd, kcompactd, RCU boost kthreads and RCU exp kworkers have been
  converted, along with a few old drivers.

  Summary of the changes:

   - Consolidate a bunch of ad-hoc implementations of
     kthread_run_on_cpu()

   - Introduce task_cpu_fallback_mask() that defines the default last
     resort affinity of a task to become nohz_full aware

   - Add some correctness check to ensure kthread_bind() is always
     called before the first kthread wake up.

   - Default affine kthread to its preferred node.

   - Convert kswapd / kcompactd and remove their halfway working ad-hoc
     affinity implementation

   - Implement kthreads preferred affinity

   - Unify kthread worker and kthread API's style

   - Convert RCU kthreads to the new API and remove the ad-hoc affinity
     implementation"

* tag 'kthread-for-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks:
  kthread: modify kernel-doc function name to match code
  rcu: Use kthread preferred affinity for RCU exp kworkers
  treewide: Introduce kthread_run_worker[_on_cpu]()
  kthread: Unify kthread_create_on_cpu() and kthread_create_worker_on_cpu() automatic format
  rcu: Use kthread preferred affinity for RCU boost
  kthread: Implement preferred affinity
  mm: Create/affine kswapd to its preferred node
  mm: Create/affine kcompactd to its preferred node
  kthread: Default affine kthread to its preferred NUMA node
  kthread: Make sure kthread hasn't started while binding it
  sched,arm64: Handle CPU isolation on last resort fallback rq selection
  arm64: Exclude nohz_full CPUs from 32bits el0 support
  lib: test_objpool: Use kthread_run_on_cpu()
  kallsyms: Use kthread_run_on_cpu()
  soc/qman: test: Use kthread_run_on_cpu()
  arm/bL_switcher: Use kthread_run_on_cpu()
 2025-01-21 17:10:05 -08:00
Linus Torvalds
96c84703f1 drm next for 6.14-rc1 
core:
 - device memory cgroup controller added
 - Remove driver date from drm_driver
 - Add drm_printer based hex dumper
 - drm memory stats docs update
 - scheduler documentation improvements
 
 new driver:
 - amdxdna - Ryzen AI NPU support
 
 connector:
 - add a mutex to protect ELD
 - make connector setup two-step
 
 panels:
 - Introduce backlight quirks infrastructure
 - New panels: KDB KD116N2130B12, Tianma TM070JDHG34-00,
 - Multi-Inno Technology MI1010Z1T-1CP11
 
 bridge:
 - ti-sn65dsi83: Add ti,lvds-vod-swing optional properties
 - Provide default implementation of atomic_check for HDMI bridges
 - it605: HDCP improvements, MCCS Support
 
 xe:
 - make OA buffer size configurable
 - GuC capture fixes
 - add ufence and g2h flushes
 - restore system memory GGTT mappings
 - ioctl fixes
 - SRIOV PF scheduling priority
 - allow fault injection
 - lots of improvements/refactors
 - Enable GuC's WA_DUAL_QUEUE for newer platforms
 - IRQ related fixes and improvements
 
 i915:
 - More accurate engine busyness metrics with GuC submission
 - Ensure partial BO segment offset never exceeds allowed max
 - Flush GuC CT receive tasklet during reset preparation
 - Some DG2 refactor to fix DG2 bugs when operating with certain CPUs
 - Fix DG1 power gate sequence
 - Enabling uncompressed 128b/132b UHBR SST
 - Handle hdmi connector init failures, and no HDMI/DP cases
 - More robust engine resets on Haswell and older
 
 i915/xe display:
 - HDCP fixes for Xe3Lpd
 - New GSC FW ARL-H/ARL-U
 - support 3 VDSC engines 12 slices
 - MBUS joining sanitisation
 - reconcile i915/xe display power mgmt
 - Xe3Lpd fixes
 - UHBR rates for Thunderbolt
 
 amdgpu:
 - DRM panic support
 - track BO memory stats at runtime
 - Fix max surface handling in DC
 - Cleaner shader support for gfx10.3 dGPUs
 - fix drm buddy trim handling
 - SDMA engine reset updates
 - Fix doorbell ttm cleanup
 - RAS updates
 - ISP updates
 - SDMA queue reset support
 - Rework DPM powergating interfaces
 - Documentation updates and cleanups
 - DCN 3.5 updates
 - Use a pm notifier to more gracefully handle VRAM eviction on suspend or hibernate
 - Add debugfs interfaces for forcing scheduling to specific engine instances
 - GG 9.5 updates
 - IH 4.4 updates
 - Make missing optional firmware less noisy
 - PSP 13.x updates
 - SMU 13.x updates
 - VCN 5.x updates
 - JPEG 5.x updates
 - GC 12.x updates
 - DC FAMS updates
 
 amdkfd:
 - GG 9.5 updates
 - Logging improvements
 - Shader debugger fixes
 - Trap handler cleanup
 - Cleanup includes
 - Eviction fence wq fix
 
 msm:
 - MDSS:
 - properly described UBWC registers
 - added SM6150 (aka QCS615) support
 - DPU:
 - added SM6150 (aka QCS615) support
 - enabled wide planes if virtual planes are enabled (by using two SSPPs for a single plane)
 - added CWB hardware blocks support
 - DSI:
 - added SM6150 (aka QCS615) support
 - GPU:
 - Print GMU core fw version
 - GMU bandwidth voting for a740 and a750
 - Expose uche trap base via uapi
 - UAPI error reporting
 
 rcar-du:
 - Add r8a779h0 Support
 
 ivpu:
 - Fix qemu crash when using passthrough
 
 nouveau:
 - expose GSP-RM logging buffers via debugfs
 
 panfrost:
 - Add MT8188 Mali-G57 MC3 support
 
 rockchip:
 - Gamma LUT support
 
 hisilicon:
 - new HIBMC support
 
 virtio-gpu:
 - convert to helpers
 - add prime support for scanout buffers
 
 v3d:
 - Add DRM_IOCTL_V3D_PERFMON_SET_GLOBAL
 
 vc4:
 - Add support for BCM2712
 
 vkms:
 - line-per-line compositing algorithm to improve performance
 
 zynqmp:
 - Add DP audio support
 
 mediatek:
 - dp: Add sdp path reset
 - dp: Support flexible length of DP calibration data
 
 etnaviv:
 - add fdinfo memory support
 - add explicit reset handling
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Merge tag 'drm-next-2025-01-17' of https://gitlab.freedesktop.org/drm/kernel

Pull drm updates from Dave Airlie:
 "There are two external interactions of note, the msm tree pull in some
  opp tree, hopefully the opp tree arrives from the same git tree
  however it normally does.

  There is also a new cgroup controller for device memory, that is used
  by drm, so is merging through my tree. This will hopefully help open
  up gpu cgroup usage a bit more and move us forward.

  There is a new accelerator driver for the AMD XDNA Ryzen AI NPUs.

  Then the usual xe/amdgpu/i915/msm leaders and lots of changes and
  refactors across the board:

  core:
   - device memory cgroup controller added
   - Remove driver date from drm_driver
   - Add drm_printer based hex dumper
   - drm memory stats docs update
   - scheduler documentation improvements

  new driver:
   - amdxdna - Ryzen AI NPU support

  connector:
   - add a mutex to protect ELD
   - make connector setup two-step

  panels:
   - Introduce backlight quirks infrastructure
   - New panels: KDB KD116N2130B12, Tianma TM070JDHG34-00,
   - Multi-Inno Technology MI1010Z1T-1CP11

  bridge:
   - ti-sn65dsi83: Add ti,lvds-vod-swing optional properties
   - Provide default implementation of atomic_check for HDMI bridges
   - it605: HDCP improvements, MCCS Support

  xe:
   - make OA buffer size configurable
   - GuC capture fixes
   - add ufence and g2h flushes
   - restore system memory GGTT mappings
   - ioctl fixes
   - SRIOV PF scheduling priority
   - allow fault injection
   - lots of improvements/refactors
   - Enable GuC's WA_DUAL_QUEUE for newer platforms
   - IRQ related fixes and improvements

  i915:
   - More accurate engine busyness metrics with GuC submission
   - Ensure partial BO segment offset never exceeds allowed max
   - Flush GuC CT receive tasklet during reset preparation
   - Some DG2 refactor to fix DG2 bugs when operating with certain CPUs
   - Fix DG1 power gate sequence
   - Enabling uncompressed 128b/132b UHBR SST
   - Handle hdmi connector init failures, and no HDMI/DP cases
   - More robust engine resets on Haswell and older

  i915/xe display:
   - HDCP fixes for Xe3Lpd
   - New GSC FW ARL-H/ARL-U
   - support 3 VDSC engines 12 slices
   - MBUS joining sanitisation
   - reconcile i915/xe display power mgmt
   - Xe3Lpd fixes
   - UHBR rates for Thunderbolt

  amdgpu:
   - DRM panic support
   - track BO memory stats at runtime
   - Fix max surface handling in DC
   - Cleaner shader support for gfx10.3 dGPUs
   - fix drm buddy trim handling
   - SDMA engine reset updates
   - Fix doorbell ttm cleanup
   - RAS updates
   - ISP updates
   - SDMA queue reset support
   - Rework DPM powergating interfaces
   - Documentation updates and cleanups
   - DCN 3.5 updates
   - Use a pm notifier to more gracefully handle VRAM eviction on
     suspend or hibernate
   - Add debugfs interfaces for forcing scheduling to specific engine
     instances
   - GG 9.5 updates
   - IH 4.4 updates
   - Make missing optional firmware less noisy
   - PSP 13.x updates
   - SMU 13.x updates
   - VCN 5.x updates
   - JPEG 5.x updates
   - GC 12.x updates
   - DC FAMS updates

  amdkfd:
   - GG 9.5 updates
   - Logging improvements
   - Shader debugger fixes
   - Trap handler cleanup
   - Cleanup includes
   - Eviction fence wq fix

  msm:
   - MDSS:
      - properly described UBWC registers
      - added SM6150 (aka QCS615) support
   - DPU:
      - added SM6150 (aka QCS615) support
      - enabled wide planes if virtual planes are enabled (by using two
        SSPPs for a single plane)
      - added CWB hardware blocks support
   - DSI:
      - added SM6150 (aka QCS615) support
   - GPU:
      - Print GMU core fw version
      - GMU bandwidth voting for a740 and a750
      - Expose uche trap base via uapi
      - UAPI error reporting

  rcar-du:
   - Add r8a779h0 Support

  ivpu:
   - Fix qemu crash when using passthrough

  nouveau:
   - expose GSP-RM logging buffers via debugfs

  panfrost:
   - Add MT8188 Mali-G57 MC3 support

  rockchip:
   - Gamma LUT support

  hisilicon:
   - new HIBMC support

  virtio-gpu:
   - convert to helpers
   - add prime support for scanout buffers

  v3d:
   - Add DRM_IOCTL_V3D_PERFMON_SET_GLOBAL

  vc4:
   - Add support for BCM2712

  vkms:
   - line-per-line compositing algorithm to improve performance

  zynqmp:
   - Add DP audio support

  mediatek:
   - dp: Add sdp path reset
   - dp: Support flexible length of DP calibration data

  etnaviv:
   - add fdinfo memory support
   - add explicit reset handling"

* tag 'drm-next-2025-01-17' of https://gitlab.freedesktop.org/drm/kernel: (1070 commits)
  drm/bridge: fix documentation for the hdmi_audio_prepare() callback
  doc/cgroup: Fix title underline length
  drm/doc: Include new drm-compute documentation
  cgroup/dmem: Fix parameters documentation
  cgroup/dmem: Select PAGE_COUNTER
  kernel/cgroup: Remove the unused variable climit
  drm/display: hdmi: Do not read EDID on disconnected connectors
  drm/tests: hdmi: Add connector disablement test
  drm/connector: hdmi: Do atomic check when necessary
  drm/amd/display: 3.2.316
  drm/amd/display: avoid reset DTBCLK at clock init
  drm/amd/display: improve dpia pre-train
  drm/amd/display: Apply DML21 Patches
  drm/amd/display: Use HW lock mgr for PSR1
  drm/amd/display: Revised for Replay Pseudo vblank control
  drm/amd/display: Add a new flag for replay low hz
  drm/amd/display: Remove unused read_ono_state function from Hwss module
  drm/amd/display: Do not elevate mem_type change to full update
  drm/amd/display: Do not wait for PSR disable on vbl enable
  drm/amd/display: Remove unnecessary eDP power down
  ...
 2025-01-21 16:09:47 -08:00
Linus Torvalds
ad37df3bcb slab updates for 6.14 
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Merge tag 'slab-for-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab

Pull slab updates from Vlastimil Babka:

 - Move the kfree_rcu() implementation from RCU to SLAB subsystem
   (Uladzislau Rezki)

   The kfree_rcu() implementation has been historically maintained in
   the RCU subsystem. At LSF/MM we agreed to move it to SLAB, where it
   more logically belongs. The batching is planned be more integrated
   with SLUB internals in the future, while using the RCU APIs like any
   other subsystem.

 - Fix for kernel-doc warning (Randy Dunlap)

* tag 'slab-for-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
  mm/slab: fix kernel-doc func param names
  mm/slab: Move kvfree_rcu() into SLAB
  rcu/kvfree: Adjust a shrinker name
  rcu/kvfree: Adjust names passed into trace functions
  rcu/kvfree: Move some functions under CONFIG_TINY_RCU
  rcu/kvfree: Initialize kvfree_rcu() separately
 2025-01-21 13:57:20 -08:00
Linus Torvalds
6c4aa896eb Performance events changes for v6.14: 
- Seqlock optimizations that arose in a perf context and were
    merged into the perf tree:
 
    - seqlock: Add raw_seqcount_try_begin (Suren Baghdasaryan)
    - mm: Convert mm_lock_seq to a proper seqcount ((Suren Baghdasaryan)
    - mm: Introduce mmap_lock_speculate_{try_begin|retry} (Suren Baghdasaryan)
    - mm/gup: Use raw_seqcount_try_begin() (Peter Zijlstra)
 
  - Core perf enhancements:
 
    - Reduce 'struct page' footprint of perf by mapping pages
      in advance (Lorenzo Stoakes)
    - Save raw sample data conditionally based on sample type (Yabin Cui)
    - Reduce sampling overhead by checking sample_type in
      perf_sample_save_callchain() and perf_sample_save_brstack() (Yabin Cui)
    - Export perf_exclude_event() (Namhyung Kim)
 
  - Uprobes scalability enhancements: (Andrii Nakryiko)
 
    - Simplify find_active_uprobe_rcu() VMA checks
    - Add speculative lockless VMA-to-inode-to-uprobe resolution
    - Simplify session consumer tracking
    - Decouple return_instance list traversal and freeing
    - Ensure return_instance is detached from the list before freeing
    - Reuse return_instances between multiple uretprobes within task
    - Guard against kmemdup() failing in dup_return_instance()
 
  - AMD core PMU driver enhancements:
 
    - Relax privilege filter restriction on AMD IBS (Namhyung Kim)
 
  - AMD RAPL energy counters support: (Dhananjay Ugwekar)
 
    - Introduce topology_logical_core_id() (K Prateek Nayak)
 
    - Remove the unused get_rapl_pmu_cpumask() function
    - Remove the cpu_to_rapl_pmu() function
    - Rename rapl_pmu variables
    - Make rapl_model struct global
    - Add arguments to the init and cleanup functions
    - Modify the generic variable names to *_pkg*
    - Remove the global variable rapl_msrs
    - Move the cntr_mask to rapl_pmus struct
    - Add core energy counter support for AMD CPUs
 
  - Intel core PMU driver enhancements:
 
    - Support RDPMC 'metrics clear mode' feature (Kan Liang)
    - Clarify adaptive PEBS processing (Kan Liang)
    - Factor out functions for PEBS records processing (Kan Liang)
    - Simplify the PEBS records processing for adaptive PEBS (Kan Liang)
 
  - Intel uncore driver enhancements: (Kan Liang)
 
    - Convert buggy pmu->func_id use to pmu->registered
    - Support more units on Granite Rapids
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-core-2025-01-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull performance events updates from Ingo Molnar:
 "Seqlock optimizations that arose in a perf context and were merged
  into the perf tree:

   - seqlock: Add raw_seqcount_try_begin (Suren Baghdasaryan)
   - mm: Convert mm_lock_seq to a proper seqcount (Suren Baghdasaryan)
   - mm: Introduce mmap_lock_speculate_{try_begin|retry} (Suren
     Baghdasaryan)
   - mm/gup: Use raw_seqcount_try_begin() (Peter Zijlstra)

  Core perf enhancements:

   - Reduce 'struct page' footprint of perf by mapping pages in advance
     (Lorenzo Stoakes)
   - Save raw sample data conditionally based on sample type (Yabin Cui)
   - Reduce sampling overhead by checking sample_type in
     perf_sample_save_callchain() and perf_sample_save_brstack() (Yabin
     Cui)
   - Export perf_exclude_event() (Namhyung Kim)

  Uprobes scalability enhancements: (Andrii Nakryiko)

   - Simplify find_active_uprobe_rcu() VMA checks
   - Add speculative lockless VMA-to-inode-to-uprobe resolution
   - Simplify session consumer tracking
   - Decouple return_instance list traversal and freeing
   - Ensure return_instance is detached from the list before freeing
   - Reuse return_instances between multiple uretprobes within task
   - Guard against kmemdup() failing in dup_return_instance()

  AMD core PMU driver enhancements:

   - Relax privilege filter restriction on AMD IBS (Namhyung Kim)

  AMD RAPL energy counters support: (Dhananjay Ugwekar)

   - Introduce topology_logical_core_id() (K Prateek Nayak)
   - Remove the unused get_rapl_pmu_cpumask() function
   - Remove the cpu_to_rapl_pmu() function
   - Rename rapl_pmu variables
   - Make rapl_model struct global
   - Add arguments to the init and cleanup functions
   - Modify the generic variable names to *_pkg*
   - Remove the global variable rapl_msrs
   - Move the cntr_mask to rapl_pmus struct
   - Add core energy counter support for AMD CPUs

  Intel core PMU driver enhancements:

   - Support RDPMC 'metrics clear mode' feature (Kan Liang)
   - Clarify adaptive PEBS processing (Kan Liang)
   - Factor out functions for PEBS records processing (Kan Liang)
   - Simplify the PEBS records processing for adaptive PEBS (Kan Liang)

  Intel uncore driver enhancements: (Kan Liang)

   - Convert buggy pmu->func_id use to pmu->registered
   - Support more units on Granite Rapids"

* tag 'perf-core-2025-01-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
  perf: map pages in advance
  perf/x86/intel/uncore: Support more units on Granite Rapids
  perf/x86/intel/uncore: Clean up func_id
  perf/x86/intel: Support RDPMC metrics clear mode
  uprobes: Guard against kmemdup() failing in dup_return_instance()
  perf/x86: Relax privilege filter restriction on AMD IBS
  perf/core: Export perf_exclude_event()
  uprobes: Reuse return_instances between multiple uretprobes within task
  uprobes: Ensure return_instance is detached from the list before freeing
  uprobes: Decouple return_instance list traversal and freeing
  uprobes: Simplify session consumer tracking
  uprobes: add speculative lockless VMA-to-inode-to-uprobe resolution
  uprobes: simplify find_active_uprobe_rcu() VMA checks
  mm: introduce mmap_lock_speculate_{try_begin|retry}
  mm: convert mm_lock_seq to a proper seqcount
  mm/gup: Use raw_seqcount_try_begin()
  seqlock: add raw_seqcount_try_begin
  perf/x86/rapl: Add core energy counter support for AMD CPUs
  perf/x86/rapl: Move the cntr_mask to rapl_pmus struct
  perf/x86/rapl: Remove the global variable rapl_msrs
  ...
 2025-01-21 10:52:03 -08:00
Linus Torvalds
7e587c20ad vfs-6.14-rc1.libfs 
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Merge tag 'vfs-6.14-rc1.libfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs libfs updates from Christian Brauner:
 "This improves the stable directory offset behavior in various ways.

  Stable offsets are needed so that NFS can reliably read directories on
  filesystems such as tmpfs:

   - Improve the end-of-directory detection

     According to getdents(3), the d_off field in each returned
     directory entry points to the next entry in the directory. The
     d_off field in the last returned entry in the readdir buffer must
     contain a valid offset value, but if it points to an actual
     directory entry, then readdir/getdents can loop.

     Introduce a specific fixed offset value that is placed in the d_off
     field of the last entry in a directory. Some user space
     applications assume that the EOD offset value is larger than the
     offsets of real directory entries, so the largest valid offset
     value is reserved for this purpose. This new value is never
     allocated by simple_offset_add().

     When ->iterate_dir() returns, getdents{64} inserts the ctx->pos
     value into the d_off field of the last valid entry in the readdir
     buffer. When it hits EOD, offset_readdir() sets ctx->pos to the EOD
     offset value so the last entry is updated to point to the EOD
     marker.

     When trying to read the entry at the EOD offset, offset_readdir()
     terminates immediately.

   - Rely on d_children to iterate stable offset directories

     Instead of using the mtree to emit entries in the order of their
     offset values, use it only to map incoming ctx->pos to a starting
     entry. Then use the directory's d_children list, which is already
     maintained properly by the dcache, to find the next child to emit.

   - Narrow the range of directory offset values returned by
     simple_offset_add() to 3 .. (S32_MAX - 1) on all platforms. This
     means the allocation behavior is identical on 32-bit systems,
     64-bit systems, and 32-bit user space on 64-bit kernels. The new
     range still permits over 2 billion concurrent entries per
     directory.

   - Return ENOSPC when the directory offset range is exhausted. Hitting
     this error is almost impossible though.

   - Remove the simple_offset_empty() helper"

* tag 'vfs-6.14-rc1.libfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  libfs: Use d_children list to iterate simple_offset directories
  libfs: Replace simple_offset end-of-directory detection
  Revert "libfs: fix infinite directory reads for offset dir"
  Revert "libfs: Add simple_offset_empty()"
  libfs: Return ENOSPC when the directory offset range is exhausted
 2025-01-20 11:00:53 -08:00
Linus Torvalds
4b84a4c8d4 vfs-6.14-rc1.misc 
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Merge tag 'vfs-6.14-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull misc vfs updates from Christian Brauner:
 "Features:

   - Support caching symlink lengths in inodes

     The size is stored in a new union utilizing the same space as
     i_devices, thus avoiding growing the struct or taking up any more
     space

     When utilized it dodges strlen() in vfs_readlink(), giving about
     1.5% speed up when issuing readlink on /initrd.img on ext4

   - Add RWF_DONTCACHE iocb and FOP_DONTCACHE file_operations flag

     If a file system supports uncached buffered IO, it may set
     FOP_DONTCACHE and enable support for RWF_DONTCACHE.

     If RWF_DONTCACHE is attempted without the file system supporting
     it, it'll get errored with -EOPNOTSUPP

   - Enable VBOXGUEST and VBOXSF_FS on ARM64

     Now that VirtualBox is able to run as a host on arm64 (e.g. the
     Apple M3 processors) we can enable VBOXSF_FS (and in turn
     VBOXGUEST) for this architecture.

     Tested with various runs of bonnie++ and dbench on an Apple MacBook
     Pro with the latest Virtualbox 7.1.4 r165100 installed

  Cleanups:

   - Delay sysctl_nr_open check in expand_files()

   - Use kernel-doc includes in fiemap docbook

   - Use page->private instead of page->index in watch_queue

   - Use a consume fence in mnt_idmap() as it's heavily used in
     link_path_walk()

   - Replace magic number 7 with ARRAY_SIZE() in fc_log

   - Sort out a stale comment about races between fd alloc and dup2()

   - Fix return type of do_mount() from long to int

   - Various cosmetic cleanups for the lockref code

  Fixes:

   - Annotate spinning as unlikely() in __read_seqcount_begin

     The annotation already used to be there, but got lost in commit
     52ac39e5db ("seqlock: seqcount_t: Implement all read APIs as
     statement expressions")

   - Fix proc_handler for sysctl_nr_open

   - Flush delayed work in delayed fput()

   - Fix grammar and spelling in propagate_umount()

   - Fix ESP not readable during coredump

     In /proc/PID/stat, there is the kstkesp field which is the stack
     pointer of a thread. While the thread is active, this field reads
     zero. But during a coredump, it should have a valid value

     However, at the moment, kstkesp is zero even during coredump

   - Don't wake up the writer if the pipe is still full

   - Fix unbalanced user_access_end() in select code"

* tag 'vfs-6.14-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (28 commits)
  gfs2: use lockref_init for qd_lockref
  erofs: use lockref_init for pcl->lockref
  dcache: use lockref_init for d_lockref
  lockref: add a lockref_init helper
  lockref: drop superfluous externs
  lockref: use bool for false/true returns
  lockref: improve the lockref_get_not_zero description
  lockref: remove lockref_put_not_zero
  fs: Fix return type of do_mount() from long to int
  select: Fix unbalanced user_access_end()
  vbox: Enable VBOXGUEST and VBOXSF_FS on ARM64
  pipe_read: don't wake up the writer if the pipe is still full
  selftests: coredump: Add stackdump test
  fs/proc: do_task_stat: Fix ESP not readable during coredump
  fs: add RWF_DONTCACHE iocb and FOP_DONTCACHE file_operations flag
  fs: sort out a stale comment about races between fd alloc and dup2
  fs: Fix grammar and spelling in propagate_umount()
  fs: fc_log replace magic number 7 with ARRAY_SIZE()
  fs: use a consume fence in mnt_idmap()
  file: flush delayed work in delayed fput()
  ...
 2025-01-20 09:40:49 -08:00
Vlastimil Babka
e492fac365 Merge branch 'slab/for-6.14/kfree_rcu_move' into slab/for-next 
Merge the slab feature branch for 6.14:

- Move the kfree_rcu() implementation from RCU to SLAB subsystem
  (Uladzislau Rezki)
 2025-01-17 13:10:21 +01:00
Yosry Ahmed
779b9955f6 mm: zswap: move allocations during CPU init outside the lock 
In zswap_cpu_comp_prepare(), allocations are made and assigned to various
members of acomp_ctx under acomp_ctx->mutex.  However, allocations may
recurse into zswap through reclaim, trying to acquire the same mutex and
deadlocking.

Move the allocations before the mutex critical section.  Only the
initialization of acomp_ctx needs to be done with the mutex held.

Link: https://lkml.kernel.org/r/20250113214458.2123410-1-yosryahmed@google.com
Fixes: 12dcb0ef54 ("mm: zswap: properly synchronize freeing resources during CPU hotunplug")
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-15 21:15:43 -08:00
Liu Shixin
f1897f2f08 mm: khugepaged: fix call hpage_collapse_scan_file() for anonymous vma 
syzkaller reported such a BUG_ON():

 ------------[ cut here ]------------
 kernel BUG at mm/khugepaged.c:1835!
 Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
 ...
 CPU: 6 UID: 0 PID: 8009 Comm: syz.15.106 Kdump: loaded Tainted: G        W          6.13.0-rc6 #22
 Tainted: [W]=WARN
 Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
 pstate: 00400005 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : collapse_file+0xa44/0x1400
 lr : collapse_file+0x88/0x1400
 sp : ffff80008afe3a60
 ...
 Call trace:
  collapse_file+0xa44/0x1400 (P)
  hpage_collapse_scan_file+0x278/0x400
  madvise_collapse+0x1bc/0x678
  madvise_vma_behavior+0x32c/0x448
  madvise_walk_vmas.constprop.0+0xbc/0x140
  do_madvise.part.0+0xdc/0x2c8
  __arm64_sys_madvise+0x68/0x88
  invoke_syscall+0x50/0x120
  el0_svc_common.constprop.0+0xc8/0xf0
  do_el0_svc+0x24/0x38
  el0_svc+0x34/0x128
  el0t_64_sync_handler+0xc8/0xd0
  el0t_64_sync+0x190/0x198

This indicates that the pgoff is unaligned.  After analysis, I confirm the
vma is mapped to /dev/zero.  Such a vma certainly has vm_file, but it is
set to anonymous by mmap_zero().  So even if it's mmapped by 2m-unaligned,
it can pass the check in thp_vma_allowable_order() as it is an
anonymous-mmap, but then be collapsed as a file-mmap.

It seems the problem has existed for a long time, but actually, since we
have khugepaged_max_ptes_none check before, we will skip collapse it as it
is /dev/zero and so has no present page.  But commit d8ea7cc854 limit
the check for only khugepaged, so the BUG_ON() can be triggered by
madvise_collapse().

Add vma_is_anonymous() check to make such vma be processed by
hpage_collapse_scan_pmd().

Link: https://lkml.kernel.org/r/20250111034511.2223353-1-liushixin2@huawei.com
Fixes: d8ea7cc854 ("mm/khugepaged: add flag to predicate khugepaged-only behavior")
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: Yang Shi <yang@os.amperecomputing.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mattew Wilcox <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-15 21:15:43 -08:00
Karan Sanghavi
b071cc3546 mm: shmem: use signed int for version handling in casefold option 
Fixes an issue where the use of an unsigned data type in
`shmem_parse_opt_casefold()` caused incorrect evaluation of negative
conditions.

Link: https://lkml.kernel.org/r/20250111-unsignedcompare1601569-v3-1-c861b4221831@gmail.com
Fixes: 58e55efd6c ("tmpfs: Add casefold lookup support")
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Reviewed-by: Gabriel Krisman Bertazi <gabriel@krisman.be>
Signed-off-by: Karan Sanghavi <karansanghvi98@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Hugh Dickens <hughd@google.com>
Cc: Shuah khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-15 21:15:43 -08:00
zihan zhou
9726891fe7 mm: page_alloc: fix missed updates of lowmem_reserve in adjust_managed_page_count 
In the kernel, the zone's lowmem_reserve and _watermark, and the global
variable 'totalreserve_pages' depend on the value of managed_pages, but
after running adjust_managed_page_count, these values aren't updated,
which causes some problems.

For example, in a system with six 1GB large pages, we found that the value
of protection in zoneinfo (zone->lowmem_reserve), is not right.  Its value
seems to be calculated from the initial managed_pages, but after the
managed_pages changed, was not updated.  Only after reading the file
/proc/sys/vm/lowmem_reserve_ratio, updates happen.

read file /proc/sys/vm/lowmem_reserve_ratio:

lowmem_reserve_ratio_sysctl_handler
----setup_per_zone_lowmem_reserve
--------calculate_totalreserve_pages

protection changed after reading file:

[root@test ~]# cat /proc/zoneinfo | grep protection
        protection: (0, 2719, 57360, 0)
        protection: (0, 0, 54640, 0)
        protection: (0, 0, 0, 0)
        protection: (0, 0, 0, 0)
[root@test ~]# cat /proc/sys/vm/lowmem_reserve_ratio
256     256     32      0
[root@test ~]# cat /proc/zoneinfo | grep protection
        protection: (0, 2735, 63524, 0)
        protection: (0, 0, 60788, 0)
        protection: (0, 0, 0, 0)
        protection: (0, 0, 0, 0)

lowmem_reserve increased also makes the totalreserve_pages increased,
which causes a decrease in available memory.  The one above is just a test
machine, and the increase is not significant.  On our online machine, the
reserved memory will increase by several GB due to reading this file.  It
is clearly unreasonable to cause a sharp drop in available memory just by
reading a file.

In this patch, we update reserve memory when update managed_pages, The
size of reserved memory becomes stable.  But it seems that the _watermark
should also be updated along with the managed_pages.  We have not done it
because we are unsure if it is reasonable to set the watermark through the
initial managed_pages.  If it is not reasonable, we will propose new
patch.

Link: https://lkml.kernel.org/r/20241225021034.45693-1-15645113830zzh@gmail.com
Signed-off-by: zihan zhou <15645113830zzh@gmail.com>
Signed-off-by: yaowenchao <yaowenchao@jd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-15 21:15:42 -08:00
Al Viro
f7862dfef6 saner replacement for debugfs_rename() 
Existing primitive has several problems:
	1) calling conventions are clumsy - it returns a dentry reference
that is either identical to its second argument or is an ERR_PTR(-E...);
in both cases no refcount changes happen.  Inconvenient for users and
bug-prone; it would be better to have it return 0 on success and -E... on
failure.
	2) it allows cross-directory moves; however, no such caller have
ever materialized and considering the way debugfs is used, it's unlikely
to happen in the future.  What's more, any such caller would have fun
issues to deal with wrt interplay with recursive removal.  It also makes
the calling conventions clumsier...
	3) tautological rename fails; the callers have no race-free way
to deal with that.
	4) new name must have been formed by the caller; quite a few
callers have it done by sprintf/kasprintf/etc., ending up with considerable
boilerplate.

Proposed replacement: int debugfs_change_name(dentry, fmt, ...).  All callers
convert to that easily, and it's simpler internally.

IMO debugfs_rename() should go; if we ever get a real-world use case for
cross-directory moves in debugfs, we can always look into the right way
to handle that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20250112080705.141166-21-viro@zeniv.linux.org.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 2025-01-15 13:14:37 +01:00