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commit3a06696305upstream. Patch series "mm/damon/paddr: fix large folios access and schemes handling". DAMON operations set for physical address space, namely 'paddr', treats tail pages as unaccessed always. It can also apply DAMOS action to a large folio multiple times within single DAMOS' regions walking. As a result, the monitoring output has poor quality and DAMOS works in unexpected ways when large folios are being used. Fix those. The patches were parts of Usama's hugepage_size DAMOS filter patch series[1]. The first fix has collected from there with a slight commit message change for the subject prefix. The second fix is re-written by SJ and posted as an RFC before this series. The second one also got a slight commit message change for the subject prefix. [1] https://lore.kernel.org/20250203225604.44742-1-usamaarif642@gmail.com [2] https://lore.kernel.org/20250206231103.38298-1-sj@kernel.org This patch (of 2): This effectively adds support for large folios in damon for paddr, as damon_pa_mkold/young won't get a null folio from this function and won't ignore it, hence access will be checked and reported. This also means that larger folios will be considered for different DAMOS actions like pageout, prioritization and migration. As these DAMOS actions will consider larger folios, iterate through the region at folio_size and not PAGE_SIZE intervals. This should not have an affect on vaddr, as damon_young_pmd_entry considers pmd entries. Link: https://lkml.kernel.org/r/20250207212033.45269-1-sj@kernel.org Link: https://lkml.kernel.org/r/20250207212033.45269-2-sj@kernel.org Fixes:a28397beb5("mm/damon: implement primitives for physical address space monitoring") Signed-off-by: Usama Arif <usamaarif642@gmail.com> Signed-off-by: SeongJae Park <sj@kernel.org> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
122 lines
2.9 KiB
C
122 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Common Primitives for Data Access Monitoring
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*
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* Author: SeongJae Park <sj@kernel.org>
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*/
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#include <linux/mmu_notifier.h>
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#include <linux/page_idle.h>
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#include <linux/pagemap.h>
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#include <linux/rmap.h>
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#include "ops-common.h"
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/*
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* Get an online page for a pfn if it's in the LRU list. Otherwise, returns
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* NULL.
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*
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* The body of this function is stolen from the 'page_idle_get_folio()'. We
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* steal rather than reuse it because the code is quite simple.
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*/
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struct folio *damon_get_folio(unsigned long pfn)
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{
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struct page *page = pfn_to_online_page(pfn);
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struct folio *folio;
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if (!page)
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return NULL;
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folio = page_folio(page);
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if (!folio_test_lru(folio) || !folio_try_get(folio))
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return NULL;
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if (unlikely(page_folio(page) != folio || !folio_test_lru(folio))) {
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folio_put(folio);
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folio = NULL;
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}
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return folio;
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}
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void damon_ptep_mkold(pte_t *pte, struct vm_area_struct *vma, unsigned long addr)
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{
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struct folio *folio = damon_get_folio(pte_pfn(ptep_get(pte)));
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if (!folio)
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return;
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if (ptep_clear_young_notify(vma, addr, pte))
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folio_set_young(folio);
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folio_set_idle(folio);
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folio_put(folio);
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}
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void damon_pmdp_mkold(pmd_t *pmd, struct vm_area_struct *vma, unsigned long addr)
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{
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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struct folio *folio = damon_get_folio(pmd_pfn(pmdp_get(pmd)));
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if (!folio)
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return;
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if (pmdp_clear_young_notify(vma, addr, pmd))
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folio_set_young(folio);
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folio_set_idle(folio);
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folio_put(folio);
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#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
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}
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#define DAMON_MAX_SUBSCORE (100)
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#define DAMON_MAX_AGE_IN_LOG (32)
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int damon_hot_score(struct damon_ctx *c, struct damon_region *r,
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struct damos *s)
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{
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int freq_subscore;
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unsigned int age_in_sec;
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int age_in_log, age_subscore;
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unsigned int freq_weight = s->quota.weight_nr_accesses;
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unsigned int age_weight = s->quota.weight_age;
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int hotness;
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freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE /
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damon_max_nr_accesses(&c->attrs);
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age_in_sec = (unsigned long)r->age * c->attrs.aggr_interval / 1000000;
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for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec;
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age_in_log++, age_in_sec >>= 1)
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;
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/* If frequency is 0, higher age means it's colder */
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if (freq_subscore == 0)
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age_in_log *= -1;
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/*
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* Now age_in_log is in [-DAMON_MAX_AGE_IN_LOG, DAMON_MAX_AGE_IN_LOG].
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* Scale it to be in [0, 100] and set it as age subscore.
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*/
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age_in_log += DAMON_MAX_AGE_IN_LOG;
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age_subscore = age_in_log * DAMON_MAX_SUBSCORE /
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DAMON_MAX_AGE_IN_LOG / 2;
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hotness = (freq_weight * freq_subscore + age_weight * age_subscore);
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if (freq_weight + age_weight)
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hotness /= freq_weight + age_weight;
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/*
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* Transform it to fit in [0, DAMOS_MAX_SCORE]
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*/
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hotness = hotness * DAMOS_MAX_SCORE / DAMON_MAX_SUBSCORE;
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return hotness;
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}
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int damon_cold_score(struct damon_ctx *c, struct damon_region *r,
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struct damos *s)
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{
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int hotness = damon_hot_score(c, r, s);
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/* Return coldness of the region */
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return DAMOS_MAX_SCORE - hotness;
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}
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