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126 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Waiman Long
|
a7fb0423c2 |
cgroup: Move rcu_head up near the top of cgroup_root
Commit |
||
|
Waiman Long
|
77070eeb88 |
cgroup: Avoid false cacheline sharing of read mostly rstat_cpu
The rstat_cpu and also rstat_css_list of the cgroup structure are read
mostly variables. However, they may share the same cacheline as the
subsequent rstat_flush_next and *bstat variables which can be updated
frequently. That will slow down the cgroup_rstat_cpu() call which is
called pretty frequently in the rstat code. Add a CACHELINE_PADDING()
line in between them to avoid false cacheline sharing.
A parallel kernel build on a 2-socket x86-64 server is used as the
benchmarking tool for measuring the lock hold time. Below were the lock
hold time frequency distribution before and after the patch:
Run time Before patch After patch
-------- ------------ -----------
0-01 us 9,928,562 9,820,428
01-05 us 110,151 50,935
05-10 us 270 93
10-15 us 273 146
15-20 us 135 76
20-25 us 0 2
25-30 us 1 0
It can be seen that the patch further pushes the lock hold time towards
the lower end.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
||
|
Waiman Long
|
e76d28bdf9 |
cgroup/rstat: Reduce cpu_lock hold time in cgroup_rstat_flush_locked()
When cgroup_rstat_updated() isn't being called concurrently with
cgroup_rstat_flush_locked(), its run time is pretty short. When
both are called concurrently, the cgroup_rstat_updated() run time
can spike to a pretty high value due to high cpu_lock hold time in
cgroup_rstat_flush_locked(). This can be problematic if the task calling
cgroup_rstat_updated() is a realtime task running on an isolated CPU
with a strict latency requirement. The cgroup_rstat_updated() call can
happen when there is a page fault even though the task is running in
user space most of the time.
The percpu cpu_lock is used to protect the update tree -
updated_next and updated_children. This protection is only needed when
cgroup_rstat_cpu_pop_updated() is being called. The subsequent flushing
operation which can take a much longer time does not need that protection
as it is already protected by cgroup_rstat_lock.
To reduce the cpu_lock hold time, we need to perform all the
cgroup_rstat_cpu_pop_updated() calls up front with the lock
released afterward before doing any flushing. This patch adds a new
cgroup_rstat_updated_list() function to return a singly linked list of
cgroups to be flushed.
Some instrumentation code are added to measure the cpu_lock hold time
right after lock acquisition to after releasing the lock. Parallel
kernel build on a 2-socket x86-64 server is used as the benchmarking
tool for measuring the lock hold time.
The maximum cpu_lock hold time before and after the patch are 100us and
29us respectively. So the worst case time is reduced to about 30% of
the original. However, there may be some OS or hardware noises like NMI
or SMI in the test system that can worsen the worst case value. Those
noises are usually tuned out in a real production environment to get
a better result.
OTOH, the lock hold time frequency distribution should give a better
idea of the performance benefit of the patch. Below were the frequency
distribution before and after the patch:
Hold time Before patch After patch
--------- ------------ -----------
0-01 us 804,139 13,738,708
01-05 us 9,772,767 1,177,194
05-10 us 4,595,028 4,984
10-15 us 303,481 3,562
15-20 us 78,971 1,314
20-25 us 24,583 18
25-30 us 6,908 12
30-40 us 8,015
40-50 us 2,192
50-60 us 316
60-70 us 43
70-80 us 7
80-90 us 2
>90 us 3
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
||
|
Yafang Shao
|
d23b5c5777 |
cgroup: Make operations on the cgroup root_list RCU safe
At present, when we perform operations on the cgroup root_list, we must hold the cgroup_mutex, which is a relatively heavyweight lock. In reality, we can make operations on this list RCU-safe, eliminating the need to hold the cgroup_mutex during traversal. Modifications to the list only occur in the cgroup root setup and destroy paths, which should be infrequent in a production environment. In contrast, traversal may occur frequently. Therefore, making it RCU-safe would be beneficial. Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org> |
||
|
Linus Torvalds
|
ecae0bd517 |
Many singleton patches against the MM code. The patch series which are
included in this merge do the following:
- Kemeng Shi has contributed some compation maintenance work in the
series "Fixes and cleanups to compaction".
- Joel Fernandes has a patchset ("Optimize mremap during mutual
alignment within PMD") which fixes an obscure issue with mremap()'s
pagetable handling during a subsequent exec(), based upon an
implementation which Linus suggested.
- More DAMON/DAMOS maintenance and feature work from SeongJae Park i the
following patch series:
mm/damon: misc fixups for documents, comments and its tracepoint
mm/damon: add a tracepoint for damos apply target regions
mm/damon: provide pseudo-moving sum based access rate
mm/damon: implement DAMOS apply intervals
mm/damon/core-test: Fix memory leaks in core-test
mm/damon/sysfs-schemes: Do DAMOS tried regions update for only one apply interval
- In the series "Do not try to access unaccepted memory" Adrian Hunter
provides some fixups for the recently-added "unaccepted memory' feature.
To increase the feature's checking coverage. "Plug a few gaps where
RAM is exposed without checking if it is unaccepted memory".
- In the series "cleanups for lockless slab shrink" Qi Zheng has done
some maintenance work which is preparation for the lockless slab
shrinking code.
- Qi Zheng has redone the earlier (and reverted) attempt to make slab
shrinking lockless in the series "use refcount+RCU method to implement
lockless slab shrink".
- David Hildenbrand contributes some maintenance work for the rmap code
in the series "Anon rmap cleanups".
- Kefeng Wang does more folio conversions and some maintenance work in
the migration code. Series "mm: migrate: more folio conversion and
unification".
- Matthew Wilcox has fixed an issue in the buffer_head code which was
causing long stalls under some heavy memory/IO loads. Some cleanups
were added on the way. Series "Add and use bdev_getblk()".
- In the series "Use nth_page() in place of direct struct page
manipulation" Zi Yan has fixed a potential issue with the direct
manipulation of hugetlb page frames.
- In the series "mm: hugetlb: Skip initialization of gigantic tail
struct pages if freed by HVO" has improved our handling of gigantic
pages in the hugetlb vmmemmep optimizaton code. This provides
significant boot time improvements when significant amounts of gigantic
pages are in use.
- Matthew Wilcox has sent the series "Small hugetlb cleanups" - code
rationalization and folio conversions in the hugetlb code.
- Yin Fengwei has improved mlock()'s handling of large folios in the
series "support large folio for mlock"
- In the series "Expose swapcache stat for memcg v1" Liu Shixin has
added statistics for memcg v1 users which are available (and useful)
under memcg v2.
- Florent Revest has enhanced the MDWE (Memory-Deny-Write-Executable)
prctl so that userspace may direct the kernel to not automatically
propagate the denial to child processes. The series is named "MDWE
without inheritance".
- Kefeng Wang has provided the series "mm: convert numa balancing
functions to use a folio" which does what it says.
- In the series "mm/ksm: add fork-exec support for prctl" Stefan Roesch
makes is possible for a process to propagate KSM treatment across
exec().
- Huang Ying has enhanced memory tiering's calculation of memory
distances. This is used to permit the dax/kmem driver to use "high
bandwidth memory" in addition to Optane Data Center Persistent Memory
Modules (DCPMM). The series is named "memory tiering: calculate
abstract distance based on ACPI HMAT"
- In the series "Smart scanning mode for KSM" Stefan Roesch has
optimized KSM by teaching it to retain and use some historical
information from previous scans.
- Yosry Ahmed has fixed some inconsistencies in memcg statistics in the
series "mm: memcg: fix tracking of pending stats updates values".
- In the series "Implement IOCTL to get and optionally clear info about
PTEs" Peter Xu has added an ioctl to /proc/<pid>/pagemap which permits
us to atomically read-then-clear page softdirty state. This is mainly
used by CRIU.
- Hugh Dickins contributed the series "shmem,tmpfs: general maintenance"
- a bunch of relatively minor maintenance tweaks to this code.
- Matthew Wilcox has increased the use of the VMA lock over file-backed
page faults in the series "Handle more faults under the VMA lock". Some
rationalizations of the fault path became possible as a result.
- In the series "mm/rmap: convert page_move_anon_rmap() to
folio_move_anon_rmap()" David Hildenbrand has implemented some cleanups
and folio conversions.
- In the series "various improvements to the GUP interface" Lorenzo
Stoakes has simplified and improved the GUP interface with an eye to
providing groundwork for future improvements.
- Andrey Konovalov has sent along the series "kasan: assorted fixes and
improvements" which does those things.
- Some page allocator maintenance work from Kemeng Shi in the series
"Two minor cleanups to break_down_buddy_pages".
- In thes series "New selftest for mm" Breno Leitao has developed
another MM self test which tickles a race we had between madvise() and
page faults.
- In the series "Add folio_end_read" Matthew Wilcox provides cleanups
and an optimization to the core pagecache code.
- Nhat Pham has added memcg accounting for hugetlb memory in the series
"hugetlb memcg accounting".
- Cleanups and rationalizations to the pagemap code from Lorenzo
Stoakes, in the series "Abstract vma_merge() and split_vma()".
- Audra Mitchell has fixed issues in the procfs page_owner code's new
timestamping feature which was causing some misbehaviours. In the
series "Fix page_owner's use of free timestamps".
- Lorenzo Stoakes has fixed the handling of new mappings of sealed files
in the series "permit write-sealed memfd read-only shared mappings".
- Mike Kravetz has optimized the hugetlb vmemmap optimization in the
series "Batch hugetlb vmemmap modification operations".
- Some buffer_head folio conversions and cleanups from Matthew Wilcox in
the series "Finish the create_empty_buffers() transition".
- As a page allocator performance optimization Huang Ying has added
automatic tuning to the allocator's per-cpu-pages feature, in the series
"mm: PCP high auto-tuning".
- Roman Gushchin has contributed the patchset "mm: improve performance
of accounted kernel memory allocations" which improves their performance
by ~30% as measured by a micro-benchmark.
- folio conversions from Kefeng Wang in the series "mm: convert page
cpupid functions to folios".
- Some kmemleak fixups in Liu Shixin's series "Some bugfix about
kmemleak".
- Qi Zheng has improved our handling of memoryless nodes by keeping them
off the allocation fallback list. This is done in the series "handle
memoryless nodes more appropriately".
- khugepaged conversions from Vishal Moola in the series "Some
khugepaged folio conversions".
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Merge tag 'mm-stable-2023-11-01-14-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
"Many singleton patches against the MM code. The patch series which are
included in this merge do the following:
- Kemeng Shi has contributed some compation maintenance work in the
series 'Fixes and cleanups to compaction'
- Joel Fernandes has a patchset ('Optimize mremap during mutual
alignment within PMD') which fixes an obscure issue with mremap()'s
pagetable handling during a subsequent exec(), based upon an
implementation which Linus suggested
- More DAMON/DAMOS maintenance and feature work from SeongJae Park i
the following patch series:
mm/damon: misc fixups for documents, comments and its tracepoint
mm/damon: add a tracepoint for damos apply target regions
mm/damon: provide pseudo-moving sum based access rate
mm/damon: implement DAMOS apply intervals
mm/damon/core-test: Fix memory leaks in core-test
mm/damon/sysfs-schemes: Do DAMOS tried regions update for only one apply interval
- In the series 'Do not try to access unaccepted memory' Adrian
Hunter provides some fixups for the recently-added 'unaccepted
memory' feature. To increase the feature's checking coverage. 'Plug
a few gaps where RAM is exposed without checking if it is
unaccepted memory'
- In the series 'cleanups for lockless slab shrink' Qi Zheng has done
some maintenance work which is preparation for the lockless slab
shrinking code
- Qi Zheng has redone the earlier (and reverted) attempt to make slab
shrinking lockless in the series 'use refcount+RCU method to
implement lockless slab shrink'
- David Hildenbrand contributes some maintenance work for the rmap
code in the series 'Anon rmap cleanups'
- Kefeng Wang does more folio conversions and some maintenance work
in the migration code. Series 'mm: migrate: more folio conversion
and unification'
- Matthew Wilcox has fixed an issue in the buffer_head code which was
causing long stalls under some heavy memory/IO loads. Some cleanups
were added on the way. Series 'Add and use bdev_getblk()'
- In the series 'Use nth_page() in place of direct struct page
manipulation' Zi Yan has fixed a potential issue with the direct
manipulation of hugetlb page frames
- In the series 'mm: hugetlb: Skip initialization of gigantic tail
struct pages if freed by HVO' has improved our handling of gigantic
pages in the hugetlb vmmemmep optimizaton code. This provides
significant boot time improvements when significant amounts of
gigantic pages are in use
- Matthew Wilcox has sent the series 'Small hugetlb cleanups' - code
rationalization and folio conversions in the hugetlb code
- Yin Fengwei has improved mlock()'s handling of large folios in the
series 'support large folio for mlock'
- In the series 'Expose swapcache stat for memcg v1' Liu Shixin has
added statistics for memcg v1 users which are available (and
useful) under memcg v2
- Florent Revest has enhanced the MDWE (Memory-Deny-Write-Executable)
prctl so that userspace may direct the kernel to not automatically
propagate the denial to child processes. The series is named 'MDWE
without inheritance'
- Kefeng Wang has provided the series 'mm: convert numa balancing
functions to use a folio' which does what it says
- In the series 'mm/ksm: add fork-exec support for prctl' Stefan
Roesch makes is possible for a process to propagate KSM treatment
across exec()
- Huang Ying has enhanced memory tiering's calculation of memory
distances. This is used to permit the dax/kmem driver to use 'high
bandwidth memory' in addition to Optane Data Center Persistent
Memory Modules (DCPMM). The series is named 'memory tiering:
calculate abstract distance based on ACPI HMAT'
- In the series 'Smart scanning mode for KSM' Stefan Roesch has
optimized KSM by teaching it to retain and use some historical
information from previous scans
- Yosry Ahmed has fixed some inconsistencies in memcg statistics in
the series 'mm: memcg: fix tracking of pending stats updates
values'
- In the series 'Implement IOCTL to get and optionally clear info
about PTEs' Peter Xu has added an ioctl to /proc/<pid>/pagemap
which permits us to atomically read-then-clear page softdirty
state. This is mainly used by CRIU
- Hugh Dickins contributed the series 'shmem,tmpfs: general
maintenance', a bunch of relatively minor maintenance tweaks to
this code
- Matthew Wilcox has increased the use of the VMA lock over
file-backed page faults in the series 'Handle more faults under the
VMA lock'. Some rationalizations of the fault path became possible
as a result
- In the series 'mm/rmap: convert page_move_anon_rmap() to
folio_move_anon_rmap()' David Hildenbrand has implemented some
cleanups and folio conversions
- In the series 'various improvements to the GUP interface' Lorenzo
Stoakes has simplified and improved the GUP interface with an eye
to providing groundwork for future improvements
- Andrey Konovalov has sent along the series 'kasan: assorted fixes
and improvements' which does those things
- Some page allocator maintenance work from Kemeng Shi in the series
'Two minor cleanups to break_down_buddy_pages'
- In thes series 'New selftest for mm' Breno Leitao has developed
another MM self test which tickles a race we had between madvise()
and page faults
- In the series 'Add folio_end_read' Matthew Wilcox provides cleanups
and an optimization to the core pagecache code
- Nhat Pham has added memcg accounting for hugetlb memory in the
series 'hugetlb memcg accounting'
- Cleanups and rationalizations to the pagemap code from Lorenzo
Stoakes, in the series 'Abstract vma_merge() and split_vma()'
- Audra Mitchell has fixed issues in the procfs page_owner code's new
timestamping feature which was causing some misbehaviours. In the
series 'Fix page_owner's use of free timestamps'
- Lorenzo Stoakes has fixed the handling of new mappings of sealed
files in the series 'permit write-sealed memfd read-only shared
mappings'
- Mike Kravetz has optimized the hugetlb vmemmap optimization in the
series 'Batch hugetlb vmemmap modification operations'
- Some buffer_head folio conversions and cleanups from Matthew Wilcox
in the series 'Finish the create_empty_buffers() transition'
- As a page allocator performance optimization Huang Ying has added
automatic tuning to the allocator's per-cpu-pages feature, in the
series 'mm: PCP high auto-tuning'
- Roman Gushchin has contributed the patchset 'mm: improve
performance of accounted kernel memory allocations' which improves
their performance by ~30% as measured by a micro-benchmark
- folio conversions from Kefeng Wang in the series 'mm: convert page
cpupid functions to folios'
- Some kmemleak fixups in Liu Shixin's series 'Some bugfix about
kmemleak'
- Qi Zheng has improved our handling of memoryless nodes by keeping
them off the allocation fallback list. This is done in the series
'handle memoryless nodes more appropriately'
- khugepaged conversions from Vishal Moola in the series 'Some
khugepaged folio conversions'"
[ bcachefs conflicts with the dynamically allocated shrinkers have been
resolved as per Stephen Rothwell in
https://lore.kernel.org/all/20230913093553.4290421e@canb.auug.org.au/
with help from Qi Zheng.
The clone3 test filtering conflict was half-arsed by yours truly ]
* tag 'mm-stable-2023-11-01-14-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (406 commits)
mm/damon/sysfs: update monitoring target regions for online input commit
mm/damon/sysfs: remove requested targets when online-commit inputs
selftests: add a sanity check for zswap
Documentation: maple_tree: fix word spelling error
mm/vmalloc: fix the unchecked dereference warning in vread_iter()
zswap: export compression failure stats
Documentation: ubsan: drop "the" from article title
mempolicy: migration attempt to match interleave nodes
mempolicy: mmap_lock is not needed while migrating folios
mempolicy: alloc_pages_mpol() for NUMA policy without vma
mm: add page_rmappable_folio() wrapper
mempolicy: remove confusing MPOL_MF_LAZY dead code
mempolicy: mpol_shared_policy_init() without pseudo-vma
mempolicy trivia: use pgoff_t in shared mempolicy tree
mempolicy trivia: slightly more consistent naming
mempolicy trivia: delete those ancient pr_debug()s
mempolicy: fix migrate_pages(2) syscall return nr_failed
kernfs: drop shared NUMA mempolicy hooks
hugetlbfs: drop shared NUMA mempolicy pretence
mm/damon/sysfs-test: add a unit test for damon_sysfs_set_targets()
...
|
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Nhat Pham
|
8cba9576df |
hugetlb: memcg: account hugetlb-backed memory in memory controller
Currently, hugetlb memory usage is not acounted for in the memory
controller, which could lead to memory overprotection for cgroups with
hugetlb-backed memory. This has been observed in our production system.
For instance, here is one of our usecases: suppose there are two 32G
containers. The machine is booted with hugetlb_cma=6G, and each container
may or may not use up to 3 gigantic page, depending on the workload within
it. The rest is anon, cache, slab, etc. We can set the hugetlb cgroup
limit of each cgroup to 3G to enforce hugetlb fairness. But it is very
difficult to configure memory.max to keep overall consumption, including
anon, cache, slab etc. fair.
What we have had to resort to is to constantly poll hugetlb usage and
readjust memory.max. Similar procedure is done to other memory limits
(memory.low for e.g). However, this is rather cumbersome and buggy.
Furthermore, when there is a delay in memory limits correction, (for e.g
when hugetlb usage changes within consecutive runs of the userspace
agent), the system could be in an over/underprotected state.
This patch rectifies this issue by charging the memcg when the hugetlb
folio is utilized, and uncharging when the folio is freed (analogous to
the hugetlb controller). Note that we do not charge when the folio is
allocated to the hugetlb pool, because at this point it is not owned by
any memcg.
Some caveats to consider:
* This feature is only available on cgroup v2.
* There is no hugetlb pool management involved in the memory
controller. As stated above, hugetlb folios are only charged towards
the memory controller when it is used. Host overcommit management
has to consider it when configuring hard limits.
* Failure to charge towards the memcg results in SIGBUS. This could
happen even if the hugetlb pool still has pages (but the cgroup
limit is hit and reclaim attempt fails).
* When this feature is enabled, hugetlb pages contribute to memory
reclaim protection. low, min limits tuning must take into account
hugetlb memory.
* Hugetlb pages utilized while this option is not selected will not
be tracked by the memory controller (even if cgroup v2 is remounted
later on).
Link: https://lkml.kernel.org/r/20231006184629.155543-4-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Frank van der Linden <fvdl@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun heo <tj@kernel.org>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
||
|
Waiman Long
|
13cc9ee8f8 |
cgroup: Fix incorrect css_set_rwsem reference in comment
Since commit
|
||
|
Linus Torvalds
|
7716f383a5 |
cgroup: Changes for v6.6
* Per-cpu cpu usage stats are now tracked. This currently isn't printed out
in the cgroupfs interface and can only be accessed through e.g. BPF.
Should decide on a not-too-ugly way to show per-cpu stats in cgroupfs.
* cpuset received some cleanups and prepatory patches for the pending
cpus.exclusive patchset which will allow cpuset partitions to be created
below non-partition parents, which should ease the management of partition
cpusets.
* A lot of code and documentation cleanup patches.
* tools/testing/selftests/cgroup/test_cpuset.c is added. This causes trivial
conflicts in .gitignore and Makefile under the directory against
|
||
|
Hao Jia
|
0437719c1a |
cgroup/rstat: Record the cumulative per-cpu time of cgroup and its descendants
The member variable bstat of the structure cgroup_rstat_cpu records the per-cpu time of the cgroup itself, but does not include the per-cpu time of its descendants. The per-cpu time including descendants is very useful for calculating the per-cpu usage of cgroups. Although we can indirectly obtain the total per-cpu time of the cgroup and its descendants by accumulating the per-cpu bstat of each descendant of the cgroup. But after a child cgroup is removed, we will lose its bstat information. This will cause the cumulative value to be non-monotonic, thus affecting the accuracy of cgroup per-cpu usage. So we add the subtree_bstat variable to record the total per-cpu time of this cgroup and its descendants, which is similar to "cpuacct.usage*" in cgroup v1. And this is also helpful for the migration from cgroup v1 to cgroup v2. After adding this variable, we can obtain the per-cpu time of cgroup and its descendants in user mode through eBPF/drgn, etc. And we are still trying to determine how to expose it in the cgroupfs interface. Suggested-by: Tejun Heo <tj@kernel.org> Signed-off-by: Hao Jia <jiahao.os@bytedance.com> Signed-off-by: Tejun Heo <tj@kernel.org> |
||
|
Josh Don
|
677ea015f2 |
sched: add throttled time stat for throttled children
We currently export the total throttled time for cgroups that are given a bandwidth limit. This patch extends this accounting to also account the total time that each children cgroup has been throttled. This is useful to understand the degree to which children have been affected by the throttling control. Children which are not runnable during the entire throttled period, for example, will not show any self-throttling time during this period. Expose this in a new interface, 'cpu.stat.local', which is similar to how non-hierarchical events are accounted in 'memory.events.local'. Signed-off-by: Josh Don <joshdon@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20230620183247.737942-2-joshdon@google.com |
||
|
Jakub Kicinski
|
b54a0d4094 |
bpf-next-for-netdev
-----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQTFp0I1jqZrAX+hPRXbK58LschIgwUCY2GuKgAKCRDbK58LschI gy32AP9PI0e/bUGDExKJ8g97PeeEtnpj4TTI6g+XKILtYnyXlgD/Rk4j2D/f3IBF Ha9TmqYvAUim+U/g50vUrNuoNLNJ5w8= =OKC1 -----END PGP SIGNATURE----- Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next Daniel Borkmann says: ==================== bpf-next 2022-11-02 We've added 70 non-merge commits during the last 14 day(s) which contain a total of 96 files changed, 3203 insertions(+), 640 deletions(-). The main changes are: 1) Make cgroup local storage available to non-cgroup attached BPF programs such as tc BPF ones, from Yonghong Song. 2) Avoid unnecessary deadlock detection and failures wrt BPF task storage helpers, from Martin KaFai Lau. 3) Add LLVM disassembler as default library for dumping JITed code in bpftool, from Quentin Monnet. 4) Various kprobe_multi_link fixes related to kernel modules, from Jiri Olsa. 5) Optimize x86-64 JIT with emitting BMI2-based shift instructions, from Jie Meng. 6) Improve BPF verifier's memory type compatibility for map key/value arguments, from Dave Marchevsky. 7) Only create mmap-able data section maps in libbpf when data is exposed via skeletons, from Andrii Nakryiko. 8) Add an autoattach option for bpftool to load all object assets, from Wang Yufen. 9) Various memory handling fixes for libbpf and BPF selftests, from Xu Kuohai. 10) Initial support for BPF selftest's vmtest.sh on arm64, from Manu Bretelle. 11) Improve libbpf's BTF handling to dedup identical structs, from Alan Maguire. 12) Add BPF CI and denylist documentation for BPF selftests, from Daniel Müller. 13) Check BPF cpumap max_entries before doing allocation work, from Florian Lehner. * tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (70 commits) samples/bpf: Fix typo in README bpf: Remove the obsolte u64_stats_fetch_*_irq() users. bpf: check max_entries before allocating memory bpf: Fix a typo in comment for DFS algorithm bpftool: Fix spelling mistake "disasembler" -> "disassembler" selftests/bpf: Fix bpftool synctypes checking failure selftests/bpf: Panic on hard/soft lockup docs/bpf: Add documentation for new cgroup local storage selftests/bpf: Add test cgrp_local_storage to DENYLIST.s390x selftests/bpf: Add selftests for new cgroup local storage selftests/bpf: Fix test test_libbpf_str/bpf_map_type_str bpftool: Support new cgroup local storage libbpf: Support new cgroup local storage bpf: Implement cgroup storage available to non-cgroup-attached bpf progs bpf: Refactor some inode/task/sk storage functions for reuse bpf: Make struct cgroup btf id global selftests/bpf: Tracing prog can still do lookup under busy lock selftests/bpf: Ensure no task storage failure for bpf_lsm.s prog due to deadlock detection bpf: Add new bpf_task_storage_delete proto with no deadlock detection bpf: bpf_task_storage_delete_recur does lookup first before the deadlock check ... ==================== Link: https://lore.kernel.org/r/20221102062120.5724-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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|
Yonghong Song
|
c4bcfb38a9 |
bpf: Implement cgroup storage available to non-cgroup-attached bpf progs
Similar to sk/inode/task storage, implement similar cgroup local storage.
There already exists a local storage implementation for cgroup-attached
bpf programs. See map type BPF_MAP_TYPE_CGROUP_STORAGE and helper
bpf_get_local_storage(). But there are use cases such that non-cgroup
attached bpf progs wants to access cgroup local storage data. For example,
tc egress prog has access to sk and cgroup. It is possible to use
sk local storage to emulate cgroup local storage by storing data in socket.
But this is a waste as it could be lots of sockets belonging to a particular
cgroup. Alternatively, a separate map can be created with cgroup id as the key.
But this will introduce additional overhead to manipulate the new map.
A cgroup local storage, similar to existing sk/inode/task storage,
should help for this use case.
The life-cycle of storage is managed with the life-cycle of the
cgroup struct. i.e. the storage is destroyed along with the owning cgroup
with a call to bpf_cgrp_storage_free() when cgroup itself
is deleted.
The userspace map operations can be done by using a cgroup fd as a key
passed to the lookup, update and delete operations.
Typically, the following code is used to get the current cgroup:
struct task_struct *task = bpf_get_current_task_btf();
... task->cgroups->dfl_cgrp ...
and in structure task_struct definition:
struct task_struct {
....
struct css_set __rcu *cgroups;
....
}
With sleepable program, accessing task->cgroups is not protected by rcu_read_lock.
So the current implementation only supports non-sleepable program and supporting
sleepable program will be the next step together with adding rcu_read_lock
protection for rcu tagged structures.
Since map name BPF_MAP_TYPE_CGROUP_STORAGE has been used for old cgroup local
storage support, the new map name BPF_MAP_TYPE_CGRP_STORAGE is used
for cgroup storage available to non-cgroup-attached bpf programs. The old
cgroup storage supports bpf_get_local_storage() helper to get the cgroup data.
The new cgroup storage helper bpf_cgrp_storage_get() can provide similar
functionality. While old cgroup storage pre-allocates storage memory, the new
mechanism can also pre-allocate with a user space bpf_map_update_elem() call
to avoid potential run-time memory allocation failure.
Therefore, the new cgroup storage can provide all functionality w.r.t.
the old one. So in uapi bpf.h, the old BPF_MAP_TYPE_CGROUP_STORAGE is alias to
BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED to indicate the old cgroup storage can
be deprecated since the new one can provide the same functionality.
Acked-by: David Vernet <void@manifault.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221026042850.673791-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
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|
Linus Torvalds
|
bd9a3dba18 |
PSI updates for v6.1:
- Various performance optimizations, resulting in a 4%-9% speedup
in the mmtests/config-scheduler-perfpipe micro-benchmark.
- New interface to turn PSI on/off on a per cgroup level.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-psi-2022-10-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull PSI updates from Ingo Molnar:
- Various performance optimizations, resulting in a 4%-9% speedup in
the mmtests/config-scheduler-perfpipe micro-benchmark.
- New interface to turn PSI on/off on a per cgroup level.
* tag 'sched-psi-2022-10-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/psi: Per-cgroup PSI accounting disable/re-enable interface
sched/psi: Cache parent psi_group to speed up group iteration
sched/psi: Consolidate cgroup_psi()
sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure
sched/psi: Remove NR_ONCPU task accounting
sched/psi: Optimize task switch inside shared cgroups again
sched/psi: Move private helpers to sched/stats.h
sched/psi: Save percpu memory when !psi_cgroups_enabled
sched/psi: Don't create cgroup PSI files when psi_disabled
sched/psi: Fix periodic aggregation shut off
|
||
|
Chengming Zhou
|
34f26a1561 |
sched/psi: Per-cgroup PSI accounting disable/re-enable interface
PSI accounts stalls for each cgroup separately and aggregates it
at each level of the hierarchy. This may cause non-negligible overhead
for some workloads when under deep level of the hierarchy.
commit
|
||
|
Tejun Heo
|
8a693f7766 |
cgroup: Remove CFTYPE_PRESSURE
CFTYPE_PRESSURE is used to flag PSI related files so that they are not created if PSI is disabled during boot. It's a bit weird to use a generic flag to mark a specific file type. Let's instead move the PSI files into its own cftypes array and add/rm them conditionally. This is a bit more code but cleaner. No userland visible changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> |
||
|
Tejun Heo
|
0083d27b21 |
cgroup: Improve cftype add/rm error handling
Let's track whether a cftype is currently added or not using a new flag __CFTYPE_ADDED so that duplicate operations can be failed safely and consistently allow using empty cftypes. Signed-off-by: Tejun Heo <tj@kernel.org> |
||
|
Tejun Heo
|
7f203bc89e |
cgroup: Replace cgroup->ancestor_ids[] with ->ancestors[]
Every cgroup knows all its ancestors through its ->ancestor_ids[]. There's
no advantage to remembering the IDs instead of the pointers directly and
this makes the array useless for finding an actual ancestor cgroup forcing
cgroup_ancestor() to iteratively walk up the hierarchy instead. Let's
replace cgroup->ancestor_ids[] with ->ancestors[] and remove the walking-up
from cgroup_ancestor().
While at it, improve comments around cgroup_root->cgrp_ancestor_storage.
This patch shouldn't cause user-visible behavior differences.
v2: Update cgroup_ancestor() to use ->ancestors[].
v3: cgroup_root->cgrp_ancestor_storage's type is updated to match
cgroup->ancestors[]. Better comments.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
|
||
|
Linus Torvalds
|
b6bb70f9ab |
Several core optimizations:
* threadgroup_rwsem write locking is skipped when configuring controllers in
empty subtrees. Combined with CLONE_INTO_CGROUP, this allows the common
static usage pattern to not grab threadgroup_rwsem at all (glibc still
doesn't seem ready for CLONE_INTO_CGROUP unfortunately).
* threadgroup_rwsem used to be put into non-percpu mode by default due to
latency concerns in specific use cases. There's no reason for everyone
else to pay for it. Make the behavior optional.
* psi no longer allocates memory when disabled.
along with some code cleanups.
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Merge tag 'cgroup-for-5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
"Several core optimizations:
- threadgroup_rwsem write locking is skipped when configuring
controllers in empty subtrees.
Combined with CLONE_INTO_CGROUP, this allows the common static
usage pattern to not grab threadgroup_rwsem at all (glibc still
doesn't seem ready for CLONE_INTO_CGROUP unfortunately).
- threadgroup_rwsem used to be put into non-percpu mode by default
due to latency concerns in specific use cases. There's no reason
for everyone else to pay for it. Make the behavior optional.
- psi no longer allocates memory when disabled.
... along with some code cleanups"
* tag 'cgroup-for-5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: Skip subtree root in cgroup_update_dfl_csses()
cgroup: remove "no" prefixed mount options
cgroup: Make !percpu threadgroup_rwsem operations optional
cgroup: Add "no" prefixed mount options
cgroup: Elide write-locking threadgroup_rwsem when updating csses on an empty subtree
cgroup.c: remove redundant check for mixable cgroup in cgroup_migrate_vet_dst
cgroup.c: add helper __cset_cgroup_from_root to cleanup duplicated codes
psi: dont alloc memory for psi by default
|
||
|
Linus Torvalds
|
b167fdffe9 |
This cycle's scheduler updates for v6.0 are:
Load-balancing improvements:
============================
- Improve NUMA balancing on AMD Zen systems for affine workloads.
- Improve the handling of reduced-capacity CPUs in load-balancing.
- Energy Model improvements: fix & refine all the energy fairness metrics (PELT),
and remove the conservative threshold requiring 6% energy savings to
migrate a task. Doing this improves power efficiency for most workloads,
and also increases the reliability of energy-efficiency scheduling.
- Optimize/tweak select_idle_cpu() to spend (much) less time searching
for an idle CPU on overloaded systems. There's reports of several
milliseconds spent there on large systems with large workloads ...
[ Since the search logic changed, there might be behavioral side effects. ]
- Improve NUMA imbalance behavior. On certain systems
with spare capacity, initial placement of tasks is non-deterministic,
and such an artificial placement imbalance can persist for a long time,
hurting (and sometimes helping) performance.
The fix is to make fork-time task placement consistent with runtime
NUMA balancing placement.
Note that some performance regressions were reported against this,
caused by workloads that are not memory bandwith limited, which benefit
from the artificial locality of the placement bug(s). Mel Gorman's
conclusion, with which we concur, was that consistency is better than
random workload benefits from non-deterministic bugs:
"Given there is no crystal ball and it's a tradeoff, I think it's
better to be consistent and use similar logic at both fork time
and runtime even if it doesn't have universal benefit."
- Improve core scheduling by fixing a bug in sched_core_update_cookie() that
caused unnecessary forced idling.
- Improve wakeup-balancing by allowing same-LLC wakeup of idle CPUs for newly
woken tasks.
- Fix a newidle balancing bug that introduced unnecessary wakeup latencies.
ABI improvements/fixes:
=======================
- Do not check capabilities and do not issue capability check denial messages
when a scheduler syscall doesn't require privileges. (Such as increasing niceness.)
- Add forced-idle accounting to cgroups too.
- Fix/improve the RSEQ ABI to not just silently accept unknown flags.
(No existing tooling is known to have learned to rely on the previous behavior.)
- Depreciate the (unused) RSEQ_CS_FLAG_NO_RESTART_ON_* flags.
Optimizations:
==============
- Optimize & simplify leaf_cfs_rq_list()
- Micro-optimize set_nr_{and_not,if}_polling() via try_cmpxchg().
Misc fixes & cleanups:
======================
- Fix the RSEQ self-tests on RISC-V and Glibc 2.35 systems.
- Fix a full-NOHZ bug that can in some cases result in the tick not being
re-enabled when the last SCHED_RT task is gone from a runqueue but there's
still SCHED_OTHER tasks around.
- Various PREEMPT_RT related fixes.
- Misc cleanups & smaller fixes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Load-balancing improvements:
- Improve NUMA balancing on AMD Zen systems for affine workloads.
- Improve the handling of reduced-capacity CPUs in load-balancing.
- Energy Model improvements: fix & refine all the energy fairness
metrics (PELT), and remove the conservative threshold requiring 6%
energy savings to migrate a task. Doing this improves power
efficiency for most workloads, and also increases the reliability
of energy-efficiency scheduling.
- Optimize/tweak select_idle_cpu() to spend (much) less time
searching for an idle CPU on overloaded systems. There's reports of
several milliseconds spent there on large systems with large
workloads ...
[ Since the search logic changed, there might be behavioral side
effects. ]
- Improve NUMA imbalance behavior. On certain systems with spare
capacity, initial placement of tasks is non-deterministic, and such
an artificial placement imbalance can persist for a long time,
hurting (and sometimes helping) performance.
The fix is to make fork-time task placement consistent with runtime
NUMA balancing placement.
Note that some performance regressions were reported against this,
caused by workloads that are not memory bandwith limited, which
benefit from the artificial locality of the placement bug(s). Mel
Gorman's conclusion, with which we concur, was that consistency is
better than random workload benefits from non-deterministic bugs:
"Given there is no crystal ball and it's a tradeoff, I think
it's better to be consistent and use similar logic at both fork
time and runtime even if it doesn't have universal benefit."
- Improve core scheduling by fixing a bug in
sched_core_update_cookie() that caused unnecessary forced idling.
- Improve wakeup-balancing by allowing same-LLC wakeup of idle CPUs
for newly woken tasks.
- Fix a newidle balancing bug that introduced unnecessary wakeup
latencies.
ABI improvements/fixes:
- Do not check capabilities and do not issue capability check denial
messages when a scheduler syscall doesn't require privileges. (Such
as increasing niceness.)
- Add forced-idle accounting to cgroups too.
- Fix/improve the RSEQ ABI to not just silently accept unknown flags.
(No existing tooling is known to have learned to rely on the
previous behavior.)
- Depreciate the (unused) RSEQ_CS_FLAG_NO_RESTART_ON_* flags.
Optimizations:
- Optimize & simplify leaf_cfs_rq_list()
- Micro-optimize set_nr_{and_not,if}_polling() via try_cmpxchg().
Misc fixes & cleanups:
- Fix the RSEQ self-tests on RISC-V and Glibc 2.35 systems.
- Fix a full-NOHZ bug that can in some cases result in the tick not
being re-enabled when the last SCHED_RT task is gone from a
runqueue but there's still SCHED_OTHER tasks around.
- Various PREEMPT_RT related fixes.
- Misc cleanups & smaller fixes"
* tag 'sched-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
rseq: Kill process when unknown flags are encountered in ABI structures
rseq: Deprecate RSEQ_CS_FLAG_NO_RESTART_ON_* flags
sched/core: Fix the bug that task won't enqueue into core tree when update cookie
nohz/full, sched/rt: Fix missed tick-reenabling bug in dequeue_task_rt()
sched/core: Always flush pending blk_plug
sched/fair: fix case with reduced capacity CPU
sched/core: Use try_cmpxchg in set_nr_{and_not,if}_polling
sched/core: add forced idle accounting for cgroups
sched/fair: Remove the energy margin in feec()
sched/fair: Remove task_util from effective utilization in feec()
sched/fair: Use the same cpumask per-PD throughout find_energy_efficient_cpu()
sched/fair: Rename select_idle_mask to select_rq_mask
sched, drivers: Remove max param from effective_cpu_util()/sched_cpu_util()
sched/fair: Decay task PELT values during wakeup migration
sched/fair: Provide u64 read for 32-bits arch helper
sched/fair: Introduce SIS_UTIL to search idle CPU based on sum of util_avg
sched: only perform capability check on privileged operation
sched: Remove unused function group_first_cpu()
sched/fair: Remove redundant word " *"
selftests/rseq: check if libc rseq support is registered
...
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||
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Tejun Heo
|
6a010a49b6 |
cgroup: Make !percpu threadgroup_rwsem operations optional
|
||
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Josh Don
|
1fcf54deb7 |
sched/core: add forced idle accounting for cgroups
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Tejun Heo
|
07fd5b6cdf |
cgroup: Use separate src/dst nodes when preloading css_sets for migration
Each cset (css_set) is pinned by its tasks. When we're moving tasks around
across csets for a migration, we need to hold the source and destination
csets to ensure that they don't go away while we're moving tasks about. This
is done by linking cset->mg_preload_node on either the
mgctx->preloaded_src_csets or mgctx->preloaded_dst_csets list. Using the
same cset->mg_preload_node for both the src and dst lists was deemed okay as
a cset can't be both the source and destination at the same time.
Unfortunately, this overloading becomes problematic when multiple tasks are
involved in a migration and some of them are identity noop migrations while
others are actually moving across cgroups. For example, this can happen with
the following sequence on cgroup1:
#1> mkdir -p /sys/fs/cgroup/misc/a/b
#2> echo $$ > /sys/fs/cgroup/misc/a/cgroup.procs
#3> RUN_A_COMMAND_WHICH_CREATES_MULTIPLE_THREADS &
#4> PID=$!
#5> echo $PID > /sys/fs/cgroup/misc/a/b/tasks
#6> echo $PID > /sys/fs/cgroup/misc/a/cgroup.procs
the process including the group leader back into a. In this final migration,
non-leader threads would be doing identity migration while the group leader
is doing an actual one.
After #3, let's say the whole process was in cset A, and that after #4, the
leader moves to cset B. Then, during #6, the following happens:
1. cgroup_migrate_add_src() is called on B for the leader.
2. cgroup_migrate_add_src() is called on A for the other threads.
3. cgroup_migrate_prepare_dst() is called. It scans the src list.
4. It notices that B wants to migrate to A, so it tries to A to the dst
list but realizes that its ->mg_preload_node is already busy.
5. and then it notices A wants to migrate to A as it's an identity
migration, it culls it by list_del_init()'ing its ->mg_preload_node and
putting references accordingly.
6. The rest of migration takes place with B on the src list but nothing on
the dst list.
This means that A isn't held while migration is in progress. If all tasks
leave A before the migration finishes and the incoming task pins it, the
cset will be destroyed leading to use-after-free.
This is caused by overloading cset->mg_preload_node for both src and dst
preload lists. We wanted to exclude the cset from the src list but ended up
inadvertently excluding it from the dst list too.
This patch fixes the issue by separating out cset->mg_preload_node into
->mg_src_preload_node and ->mg_dst_preload_node, so that the src and dst
preloadings don't interfere with each other.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Mukesh Ojha <quic_mojha@quicinc.com>
Reported-by: shisiyuan <shisiyuan19870131@gmail.com>
Link: http://lkml.kernel.org/r/1654187688-27411-1-git-send-email-shisiyuan@xiaomi.com
Link: https://www.spinics.net/lists/cgroups/msg33313.html
Fixes:
|
||
|
Chen Wandun
|
5f69a6577b |
psi: dont alloc memory for psi by default
Memory about struct psi_group is allocated by default for each cgroup even if psi_disabled is true, in this case, these allocated memory is waste, so alloc memory for struct psi_group only when psi_disabled is false. Signed-off-by: Chen Wandun <chenwandun@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Tejun Heo <tj@kernel.org> |
||
|
Linus Torvalds
|
ea1ca66d3c |
Merge branch 'for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo: "Nothing too interesting. The only two noticeable changes are a subtle cpuset behavior fix and trace event id field being expanded to u64 from int. Most others are code cleanups" * 'for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cpuset: convert 'allowed' in __cpuset_node_allowed() to be boolean cgroup/rstat: check updated_next only for root cgroup: rstat: explicitly put loop variant in while cgroup: return early if it is already on preloaded list cgroup/cpuset: Don't let child cpusets restrict parent in default hierarchy cgroup: Trace event cgroup id fields should be u64 cgroup: fix a typo in comment cgroup: get the wrong css for css_alloc() during cgroup_init_subsys() cgroup: rstat: Mark benign data race to silence KCSAN |
||
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Jakub Kicinski
|
fd1740b6ab |
bpf: Remove the cgroup -> bpf header dependecy
Remove the dependency from cgroup-defs.h to bpf-cgroup.h and bpf.h. This reduces the incremental build size of x86 allmodconfig after bpf.h was touched from ~17k objects rebuilt to ~5k objects. bpf.h is 2.2kLoC and is modified relatively often. We need a new header with just the definition of struct cgroup_bpf and enum cgroup_bpf_attach_type, this is akin to cgroup-defs.h. Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/bpf/20211216025538.1649516-4-kuba@kernel.org |
||
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Wei Yang
|
af3bf05466 |
cgroup: fix a typo in comment
In commit
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||
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Daniel Borkmann
|
8520e224f5 |
bpf, cgroups: Fix cgroup v2 fallback on v1/v2 mixed mode
Fix cgroup v1 interference when non-root cgroup v2 BPF programs are used. Back in the days, commit |
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Suren Baghdasaryan
|
3958e2d0c3 |
cgroup: make per-cgroup pressure stall tracking configurable
PSI accounts stalls for each cgroup separately and aggregates it at each level of the hierarchy. This causes additional overhead with psi_avgs_work being called for each cgroup in the hierarchy. psi_avgs_work has been highly optimized, however on systems with large number of cgroups the overhead becomes noticeable. Systems which use PSI only at the system level could avoid this overhead if PSI can be configured to skip per-cgroup stall accounting. Add "cgroup_disable=pressure" kernel command-line option to allow requesting system-wide only pressure stall accounting. When set, it keeps system-wide accounting under /proc/pressure/ but skips accounting for individual cgroups and does not expose PSI nodes in cgroup hierarchy. Signed-off-by: Suren Baghdasaryan <surenb@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Tejun Heo <tj@kernel.org> |
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Tejun Heo
|
c2a1197154 | Merge branch 'for-5.13-fixes' into for-5.14 | ||
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Zhen Lei
|
08b2b6fdf6 |
cgroup: fix spelling mistakes
Fix some spelling mistakes in comments: hierarhcy ==> hierarchy automtically ==> automatically overriden ==> overridden In absense of .. or ==> In absence of .. and assocaited ==> associated taget ==> target initate ==> initiate succeded ==> succeeded curremt ==> current udpated ==> updated Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org> |
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Christian Brauner
|
661ee62809 |
cgroup: introduce cgroup.kill
Introduce the cgroup.kill file. It does what it says on the tin and allows a caller to kill a cgroup by writing "1" into cgroup.kill. The file is available in non-root cgroups. Killing cgroups is a process directed operation, i.e. the whole thread-group is affected. Consequently trying to write to cgroup.kill in threaded cgroups will be rejected and EOPNOTSUPP returned. This behavior aligns with cgroup.procs where reads in threaded-cgroups are rejected with EOPNOTSUPP. The cgroup.kill file is write-only since killing a cgroup is an event not which makes it different from e.g. freezer where a cgroup transitions between the two states. As with all new cgroup features cgroup.kill is recursive by default. Killing a cgroup is protected against concurrent migrations through the cgroup mutex. To protect against forkbombs and to mitigate the effect of racing forks a new CGRP_KILL css set lock protected flag is introduced that is set prior to killing a cgroup and unset after the cgroup has been killed. We can then check in cgroup_post_fork() where we hold the css set lock already whether the cgroup is currently being killed. If so we send the child a SIGKILL signal immediately taking it down as soon as it returns to userspace. To make the killing of the child semantically clean it is killed after all cgroup attachment operations have been finalized. There are various use-cases of this interface: - Containers usually have a conservative layout where each container usually has a delegated cgroup. For such layouts there is a 1:1 mapping between container and cgroup. If the container in addition uses a separate pid namespace then killing a container usually becomes a simple kill -9 <container-init-pid> from an ancestor pid namespace. However, there are quite a few scenarios where that isn't true. For example, there are containers that share the cgroup with other processes on purpose that are supposed to be bound to the lifetime of the container but are not in the same pidns of the container. Containers that are in a delegated cgroup but share the pid namespace with the host or other containers. - Service managers such as systemd use cgroups to group and organize processes belonging to a service. They usually rely on a recursive algorithm now to kill a service. With cgroup.kill this becomes a simple write to cgroup.kill. - Userspace OOM implementations can make good use of this feature to efficiently take down whole cgroups quickly. - The kill program can gain a new kill --cgroup /sys/fs/cgroup/delegated flag to take down cgroups. A few observations about the semantics: - If parent and child are in the same cgroup and CLONE_INTO_CGROUP is not specified we are not taking cgroup mutex meaning the cgroup can be killed while a process in that cgroup is forking. If the kill request happens right before cgroup_can_fork() and before the parent grabs its siglock the parent is guaranteed to see the pending SIGKILL. In addition we perform another check in cgroup_post_fork() whether the cgroup is being killed and is so take down the child (see above). This is robust enough and protects gainst forkbombs. If userspace really really wants to have stricter protection the simple solution would be to grab the write side of the cgroup threadgroup rwsem which will force all ongoing forks to complete before killing starts. We concluded that this is not necessary as the semantics for concurrent forking should simply align with freezer where a similar check as cgroup_post_fork() is performed. For all other cases CLONE_INTO_CGROUP is required. In this case we will grab the cgroup mutex so the cgroup can't be killed while we fork. Once we're done with the fork and have dropped cgroup mutex we are visible and will be found by any subsequent kill request. - We obviously don't kill kthreads. This means a cgroup that has a kthread will not become empty after killing and consequently no unpopulated event will be generated. The assumption is that kthreads should be in the root cgroup only anyway so this is not an issue. - We skip killing tasks that already have pending fatal signals. - Freezer doesn't care about tasks in different pid namespaces, i.e. if you have two tasks in different pid namespaces the cgroup would still be frozen. The cgroup.kill mechanism consequently behaves the same way, i.e. we kill all processes and ignore in which pid namespace they exist. - If the caller is located in a cgroup that is killed the caller will obviously be killed as well. Link: https://lore.kernel.org/r/20210503143922.3093755-1-brauner@kernel.org Cc: Shakeel Butt <shakeelb@google.com> Cc: Roman Gushchin <guro@fb.com> Cc: Tejun Heo <tj@kernel.org> Cc: cgroups@vger.kernel.org Reviewed-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Serge Hallyn <serge@hallyn.com> Acked-by: Roman Gushchin <guro@fb.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Tejun Heo <tj@kernel.org> |
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Roman Gushchin
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9d9d341df4 |
cgroup: remove obsoleted broken_hierarchy and warned_broken_hierarchy
With the deprecation of the non-hierarchical mode of the memory controller there are no more examples of broken hierarchies left. Let's remove the cgroup core code which was supposed to print warnings about creating of broken hierarchies. Link: https://lkml.kernel.org/r/20201110220800.929549-4-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Cong Wang
|
14b032b8f8 |
cgroup: Fix sock_cgroup_data on big-endian.
In order for no_refcnt and is_data to be the lowest order two
bits in the 'val' we have to pad out the bitfield of the u8.
Fixes:
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Cong Wang
|
ad0f75e5f5 |
cgroup: fix cgroup_sk_alloc() for sk_clone_lock()
When we clone a socket in sk_clone_lock(), its sk_cgrp_data is copied, so the cgroup refcnt must be taken too. And, unlike the sk_alloc() path, sock_update_netprioidx() is not called here. Therefore, it is safe and necessary to grab the cgroup refcnt even when cgroup_sk_alloc is disabled. sk_clone_lock() is in BH context anyway, the in_interrupt() would terminate this function if called there. And for sk_alloc() skcd->val is always zero. So it's safe to factor out the code to make it more readable. The global variable 'cgroup_sk_alloc_disabled' is used to determine whether to take these reference counts. It is impossible to make the reference counting correct unless we save this bit of information in skcd->val. So, add a new bit there to record whether the socket has already taken the reference counts. This obviously relies on kmalloc() to align cgroup pointers to at least 4 bytes, ARCH_KMALLOC_MINALIGN is certainly larger than that. This bug seems to be introduced since the beginning, commit |
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Linus Torvalds
|
d883600523 |
Merge branch 'for-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo: - Christian extended clone3 so that processes can be spawned into cgroups directly. This is not only neat in terms of semantics but also avoids grabbing the global cgroup_threadgroup_rwsem for migration. - Daniel added !root xattr support to cgroupfs. Userland already uses xattrs on cgroupfs for bookkeeping. This will allow delegated cgroups to support such usages. - Prateek tried to make cpuset hotplug handling synchronous but that led to possible deadlock scenarios. Reverted. - Other minor changes including release_agent_path handling cleanup. * 'for-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: docs: cgroup-v1: Document the cpuset_v2_mode mount option Revert "cpuset: Make cpuset hotplug synchronous" cgroupfs: Support user xattrs kernfs: Add option to enable user xattrs kernfs: Add removed_size out param for simple_xattr_set kernfs: kvmalloc xattr value instead of kmalloc cgroup: Restructure release_agent_path handling selftests/cgroup: add tests for cloning into cgroups clone3: allow spawning processes into cgroups cgroup: add cgroup_may_write() helper cgroup: refactor fork helpers cgroup: add cgroup_get_from_file() helper cgroup: unify attach permission checking cpuset: Make cpuset hotplug synchronous cgroup.c: Use built-in RCU list checking kselftest/cgroup: add cgroup destruction test cgroup: Clean up css_set task traversal |
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Johannes Weiner
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8a931f8013 |
mm: memcontrol: recursive memory.low protection
Right now, the effective protection of any given cgroup is capped by its
own explicit memory.low setting, regardless of what the parent says. The
reasons for this are mostly historical and ease of implementation: to make
delegation of memory.low safe, effective protection is the min() of all
memory.low up the tree.
Unfortunately, this limitation makes it impossible to protect an entire
subtree from another without forcing the user to make explicit protection
allocations all the way to the leaf cgroups - something that is highly
undesirable in real life scenarios.
Consider memory in a data center host. At the cgroup top level, we have a
distinction between system management software and the actual workload the
system is executing. Both branches are further subdivided into individual
services, job components etc.
We want to protect the workload as a whole from the system management
software, but that doesn't mean we want to protect and prioritize
individual workload wrt each other. Their memory demand can vary over
time, and we'd want the VM to simply cache the hottest data within the
workload subtree. Yet, the current memory.low limitations force us to
allocate a fixed amount of protection to each workload component in order
to get protection from system management software in general. This
results in very inefficient resource distribution.
Another concern with mandating downward allocation is that, as the
complexity of the cgroup tree grows, it gets harder for the lower levels
to be informed about decisions made at the host-level. Consider a
container inside a namespace that in turn creates its own nested tree of
cgroups to run multiple workloads. It'd be extremely difficult to
configure memory.low parameters in those leaf cgroups that on one hand
balance pressure among siblings as the container desires, while also
reflecting the host-level protection from e.g. rpm upgrades, that lie
beyond one or more delegation and namespacing points in the tree.
It's highly unusual from a cgroup interface POV that nested levels have to
be aware of and reflect decisions made at higher levels for them to be
effective.
To enable such use cases and scale configurability for complex trees, this
patch implements a resource inheritance model for memory that is similar
to how the CPU and the IO controller implement work-conserving resource
allocations: a share of a resource allocated to a subree always applies to
the entire subtree recursively, while allowing, but not mandating,
children to further specify distribution rules.
That means that if protection is explicitly allocated among siblings,
those configured shares are being followed during page reclaim just like
they are now. However, if the memory.low set at a higher level is not
fully claimed by the children in that subtree, the "floating" remainder is
applied to each cgroup in the tree in proportion to its size. Since
reclaim pressure is applied in proportion to size as well, each child in
that tree gets the same boost, and the effect is neutral among siblings -
with respect to each other, they behave as if no memory control was
enabled at all, and the VM simply balances the memory demands optimally
within the subtree. But collectively those cgroups enjoy a boost over the
cgroups in neighboring trees.
E.g. a leaf cgroup with a memory.low setting of 0 no longer means that
it's not getting a share of the hierarchically assigned resource, just
that it doesn't claim a fixed amount of it to protect from its siblings.
This allows us to recursively protect one subtree (workload) from another
(system management), while letting subgroups compete freely among each
other - without having to assign fixed shares to each leaf, and without
nested groups having to echo higher-level settings.
The floating protection composes naturally with fixed protection.
Consider the following example tree:
A A: low = 2G
/ \ A1: low = 1G
A1 A2 A2: low = 0G
As outside pressure is applied to this tree, A1 will enjoy a fixed
protection from A2 of 1G, but the remaining, unclaimed 1G from A is split
evenly among A1 and A2, coming out to 1.5G and 0.5G.
There is a slight risk of regressing theoretical setups where the
top-level cgroups don't know about the true budgeting and set bogusly high
"bypass" values that are meaningfully allocated down the tree. Such
setups would rely on unclaimed protection to be discarded, and
distributing it would change the intended behavior. Be safe and hide the
new behavior behind a mount option, 'memory_recursiveprot'.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Chris Down <chris@chrisdown.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Koutný <mkoutny@suse.com>
Link: http://lkml.kernel.org/r/20200227195606.46212-4-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Christian Brauner
|
ef2c41cf38 |
clone3: allow spawning processes into cgroups
This adds support for creating a process in a different cgroup than its parent. Callers can limit and account processes and threads right from the moment they are spawned: - A service manager can directly spawn new services into dedicated cgroups. - A process can be directly created in a frozen cgroup and will be frozen as well. - The initial accounting jitter experienced by process supervisors and daemons is eliminated with this. - Threaded applications or even thread implementations can choose to create a specific cgroup layout where each thread is spawned directly into a dedicated cgroup. This feature is limited to the unified hierarchy. Callers need to pass a directory file descriptor for the target cgroup. The caller can choose to pass an O_PATH file descriptor. All usual migration restrictions apply, i.e. there can be no processes in inner nodes. In general, creating a process directly in a target cgroup adheres to all migration restrictions. One of the biggest advantages of this feature is that CLONE_INTO_GROUP does not need to grab the write side of the cgroup cgroup_threadgroup_rwsem. This global lock makes moving tasks/threads around super expensive. With clone3() this lock is avoided. Cc: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: cgroups@vger.kernel.org Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Tejun Heo <tj@kernel.org> |
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Tejun Heo
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743210386c |
cgroup: use cgrp->kn->id as the cgroup ID
cgroup ID is currently allocated using a dedicated per-hierarchy idr and used internally and exposed through tracepoints and bpf. This is confusing because there are tracepoints and other interfaces which use the cgroupfs ino as IDs. The preceding changes made kn->id exposed as ino as 64bit ino on supported archs or ino+gen (low 32bits as ino, high gen). There's no reason for cgroup to use different IDs. The kernfs IDs are unique and userland can easily discover them and map them back to paths using standard file operations. This patch replaces cgroup IDs with kernfs IDs. * cgroup_id() is added and all cgroup ID users are converted to use it. * kernfs_node creation is moved to earlier during cgroup init so that cgroup_id() is available during init. * While at it, s/cgroup/cgrp/ in psi helpers for consistency. * Fallback ID value is changed to 1 to be consistent with root cgroup ID. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Namhyung Kim <namhyung@kernel.org> |
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Tejun Heo
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1bb5ec2eec |
cgroup: use cgroup->last_bstat instead of cgroup->bstat_pending for consistency
cgroup->bstat_pending is used to determine the base stat delta to propagate to the parent. While correct, this is different from how percpu delta is determined for no good reason and the inconsistency makes the code more difficult to understand. This patch makes parent propagation delta calculation use the same method as percpu to global propagation. * cgroup_base_stat_accumulate() is renamed to cgroup_base_stat_add() and cgroup_base_stat_sub() is added. * percpu propagation calculation is updated to use the above helpers. * cgroup->bstat_pending is replaced with cgroup->last_bstat and updated to use the same calculation as percpu propagation. Signed-off-by: Tejun Heo <tj@kernel.org> |
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Mauro Carvalho Chehab
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da82c92f11 |
docs: cgroup-v1: add it to the admin-guide book
Those files belong to the admin guide, so add them. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> |
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Linus Torvalds
|
92c1d65221 |
Merge branch 'for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo: "Documentation updates and the addition of cgroup_parse_float() which will be used by new controllers including blk-iocost" * 'for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: docs: cgroup-v1: convert docs to ReST and rename to *.rst cgroup: Move cgroup_parse_float() implementation out of CONFIG_SYSFS cgroup: add cgroup_parse_float() |
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Linus Torvalds
|
0011572c88 |
Merge branch 'for-5.2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
"This has an unusually high density of tricky fixes:
- task_get_css() could deadlock when it races against a dying cgroup.
- cgroup.procs didn't list thread group leaders with live threads.
This could mislead readers to think that a cgroup is empty when
it's not. Fixed by making PROCS iterator include dead tasks. I made
a couple mistakes making this change and this pull request contains
a couple follow-up patches.
- When cpusets run out of online cpus, it updates cpusmasks of member
tasks in bizarre ways. Joel improved the behavior significantly"
* 'for-5.2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cpuset: restore sanity to cpuset_cpus_allowed_fallback()
cgroup: Fix css_task_iter_advance_css_set() cset skip condition
cgroup: css_task_iter_skip()'d iterators must be advanced before accessed
cgroup: Include dying leaders with live threads in PROCS iterations
cgroup: Implement css_task_iter_skip()
cgroup: Call cgroup_release() before __exit_signal()
docs cgroups: add another example size for hugetlb
cgroup: Use css_tryget() instead of css_tryget_online() in task_get_css()
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Mauro Carvalho Chehab
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99c8b231ae |
docs: cgroup-v1: convert docs to ReST and rename to *.rst
Convert the cgroup-v1 files to ReST format, in order to allow a later addition to the admin-guide. The conversion is actually: - add blank lines and identation in order to identify paragraphs; - fix tables markups; - add some lists markups; - mark literal blocks; - adjust title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Tejun Heo <tj@kernel.org> |
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Jens Axboe
|
cf8929885d |
cgroup/bfq: revert bfq.weight symlink change
There's some discussion on how to do this the best, and Tejun prefers that BFQ just create the file itself instead of having cgroups support a symlink feature. Hence revert commit |
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Angelo Ruocco
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54b7b868e8 |
cgroup: let a symlink too be created with a cftype file
This commit enables a cftype to have a symlink (of any name) that points to the file associated with the cftype. Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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Chris Down
|
9852ae3fe5 |
mm, memcg: consider subtrees in memory.events
memory.stat and other files already consider subtrees in their output, and
we should too in order to not present an inconsistent interface.
The current situation is fairly confusing, because people interacting with
cgroups expect hierarchical behaviour in the vein of memory.stat,
cgroup.events, and other files. For example, this causes confusion when
debugging reclaim events under low, as currently these always read "0" at
non-leaf memcg nodes, which frequently causes people to misdiagnose breach
behaviour. The same confusion applies to other counters in this file when
debugging issues.
Aggregation is done at write time instead of at read-time since these
counters aren't hot (unlike memory.stat which is per-page, so it does it
at read time), and it makes sense to bundle this with the file
notifications.
After this patch, events are propagated up the hierarchy:
[root@ktst ~]# cat /sys/fs/cgroup/system.slice/memory.events
low 0
high 0
max 0
oom 0
oom_kill 0
[root@ktst ~]# systemd-run -p MemoryMax=1 true
Running as unit: run-r251162a189fb4562b9dabfdc9b0422f5.service
[root@ktst ~]# cat /sys/fs/cgroup/system.slice/memory.events
low 0
high 0
max 7
oom 1
oom_kill 1
As this is a change in behaviour, this can be reverted to the old
behaviour by mounting with the `memory_localevents' flag set. However, we
use the new behaviour by default as there's a lack of evidence that there
are any current users of memory.events that would find this change
undesirable.
akpm: this is a behaviour change, so Cc:stable. THis is so that
forthcoming distros which use cgroup v2 are more likely to pick up the
revised behaviour.
Link: http://lkml.kernel.org/r/20190208224419.GA24772@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
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Tejun Heo
|
c03cd7738a |
cgroup: Include dying leaders with live threads in PROCS iterations
CSS_TASK_ITER_PROCS currently iterates live group leaders; however, this means that a process with dying leader and live threads will be skipped. IOW, cgroup.procs might be empty while cgroup.threads isn't, which is confusing to say the least. Fix it by making cset track dying tasks and include dying leaders with live threads in PROCS iteration. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Topi Miettinen <toiwoton@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> |
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Roman Gushchin
|
76f969e894 |
cgroup: cgroup v2 freezer
Cgroup v1 implements the freezer controller, which provides an ability
to stop the workload in a cgroup and temporarily free up some
resources (cpu, io, network bandwidth and, potentially, memory)
for some other tasks. Cgroup v2 lacks this functionality.
This patch implements freezer for cgroup v2.
Cgroup v2 freezer tries to put tasks into a state similar to jobctl
stop. This means that tasks can be killed, ptraced (using
PTRACE_SEIZE*), and interrupted. It is possible to attach to
a frozen task, get some information (e.g. read registers) and detach.
It's also possible to migrate a frozen tasks to another cgroup.
This differs cgroup v2 freezer from cgroup v1 freezer, which mostly
tried to imitate the system-wide freezer. However uninterruptible
sleep is fine when all tasks are going to be frozen (hibernation case),
it's not the acceptable state for some subset of the system.
Cgroup v2 freezer is not supporting freezing kthreads.
If a non-root cgroup contains kthread, the cgroup still can be frozen,
but the kthread will remain running, the cgroup will be shown
as non-frozen, and the notification will not be delivered.
* PTRACE_ATTACH is not working because non-fatal signal delivery
is blocked in frozen state.
There are some interface differences between cgroup v1 and cgroup v2
freezer too, which are required to conform the cgroup v2 interface
design principles:
1) There is no separate controller, which has to be turned on:
the functionality is always available and is represented by
cgroup.freeze and cgroup.events cgroup control files.
2) The desired state is defined by the cgroup.freeze control file.
Any hierarchical configuration is allowed.
3) The interface is asynchronous. The actual state is available
using cgroup.events control file ("frozen" field). There are no
dedicated transitional states.
4) It's allowed to make any changes with the cgroup hierarchy
(create new cgroups, remove old cgroups, move tasks between cgroups)
no matter if some cgroups are frozen.
Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
No-objection-from-me-by: Oleg Nesterov <oleg@redhat.com>
Cc: kernel-team@fb.com
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Roman Gushchin
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4dcabece4c |
cgroup: protect cgroup->nr_(dying_)descendants by css_set_lock
The number of descendant cgroups and the number of dying descendant cgroups are currently synchronized using the cgroup_mutex. The number of descendant cgroups will be required by the cgroup v2 freezer, which will use it to determine if a cgroup is frozen (depending on total number of descendants and number of frozen descendants). It's not always acceptable to grab the cgroup_mutex, especially from quite hot paths (e.g. exit()). To avoid this, let's additionally synchronize these counters using the css_set_lock. So, it's safe to read these counters with either cgroup_mutex or css_set_lock locked, and for changing both locks should be acquired. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: kernel-team@fb.com |
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Linus Torvalds
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1fc1cd8399 |
Merge branch 'for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo: - Oleg's pids controller accounting update which gets rid of rcu delay in pids accounting updates - rstat (cgroup hierarchical stat collection mechanism) optimization - Doc updates * 'for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cpuset: remove unused task_has_mempolicy() cgroup, rstat: Don't flush subtree root unless necessary cgroup: add documentation for pids.events file Documentation: cgroup-v2: eliminate markup warnings MAINTAINERS: Update cgroup entry cgroup/pids: turn cgroup_subsys->free() into cgroup_subsys->release() to fix the accounting |