The patch titled Subject: mm/damon: avoid applying DAMOS action to same entity multiple times has been added to the -mm mm-unstable branch. Its filename is mm-damon-avoid-applying-damos-action-to-same-entity-multiple-times.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days
------------------------------------------------------ From: SeongJae Park sj@kernel.org Subject: mm/damon: avoid applying DAMOS action to same entity multiple times Date: Fri, 7 Feb 2025 13:20:33 -0800
'paddr' DAMON operations set can apply a DAMOS scheme's action to a large folio multiple times in single DAMOS-regions-walk if the folio is laid on multiple DAMON regions. Add a field for DAMOS scheme object that can be used by the underlying ops to know what was the last entity that the scheme's action has applied. The core layer unsets the field when each DAMOS-regions-walk is done for the given scheme. And update 'paddr' ops to use the infrastructure to avoid the problem.
Link: https://lkml.kernel.org/r/20250207212033.45269-3-sj@kernel.org Fixes: 57223ac29584 ("mm/damon/paddr: support the pageout scheme") Signed-off-by: SeongJae Park sj@kernel.org Reported-by: Usama Arif usamaarif642@gmail.com Closes: https://lore.kernel.org/20250203225604.44742-3-usamaarif642@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
include/linux/damon.h | 11 +++++++++++ mm/damon/core.c | 1 + mm/damon/paddr.c | 39 +++++++++++++++++++++++++++------------ 3 files changed, 39 insertions(+), 12 deletions(-)
--- a/include/linux/damon.h~mm-damon-avoid-applying-damos-action-to-same-entity-multiple-times +++ a/include/linux/damon.h @@ -432,6 +432,7 @@ struct damos_access_pattern { * @wmarks: Watermarks for automated (in)activation of this scheme. * @target_nid: Destination node if @action is "migrate_{hot,cold}". * @filters: Additional set of &struct damos_filter for &action. + * @last_applied: Last @action applied ops-managing entity. * @stat: Statistics of this scheme. * @list: List head for siblings. * @@ -454,6 +455,15 @@ struct damos_access_pattern { * implementation could check pages of the region and skip &action to respect * &filters * + * The minimum entity that @action can be applied depends on the underlying + * &struct damon_operations. Since it may not be aligned with the core layer + * abstract, namely &struct damon_region, &struct damon_operations could apply + * @action to same entity multiple times. Large folios that underlying on + * multiple &struct damon region objects could be such examples. The &struct + * damon_operations can use @last_applied to avoid that. DAMOS core logic + * unsets @last_applied when each regions walking for applying the scheme is + * finished. + * * After applying the &action to each region, &stat_count and &stat_sz is * updated to reflect the number of regions and total size of regions that the * &action is applied. @@ -477,6 +487,7 @@ struct damos { int target_nid; }; struct list_head filters; + void *last_applied; struct damos_stat stat; struct list_head list; }; --- a/mm/damon/core.c~mm-damon-avoid-applying-damos-action-to-same-entity-multiple-times +++ a/mm/damon/core.c @@ -1851,6 +1851,7 @@ static void kdamond_apply_schemes(struct s->next_apply_sis = c->passed_sample_intervals + (s->apply_interval_us ? s->apply_interval_us : c->attrs.aggr_interval) / sample_interval; + s->last_applied = NULL; } }
--- a/mm/damon/paddr.c~mm-damon-avoid-applying-damos-action-to-same-entity-multiple-times +++ a/mm/damon/paddr.c @@ -243,6 +243,17 @@ static bool damos_pa_filter_out(struct d return false; }
+static bool damon_pa_invalid_damos_folio(struct folio *folio, struct damos *s) +{ + if (!folio) + return true; + if (folio == s->last_applied) { + folio_put(folio); + return true; + } + return false; +} + static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s, unsigned long *sz_filter_passed) { @@ -250,6 +261,7 @@ static unsigned long damon_pa_pageout(st LIST_HEAD(folio_list); bool install_young_filter = true; struct damos_filter *filter; + struct folio *folio;
/* check access in page level again by default */ damos_for_each_filter(filter, s) { @@ -268,9 +280,8 @@ static unsigned long damon_pa_pageout(st
addr = r->ar.start; while (addr < r->ar.end) { - struct folio *folio = damon_get_folio(PHYS_PFN(addr)); - - if (!folio) { + folio = damon_get_folio(PHYS_PFN(addr)); + if (damon_pa_invalid_damos_folio(folio, s)) { addr += PAGE_SIZE; continue; } @@ -296,6 +307,7 @@ put_folio: damos_destroy_filter(filter); applied = reclaim_pages(&folio_list); cond_resched(); + s->last_applied = folio; return applied * PAGE_SIZE; }
@@ -304,12 +316,12 @@ static inline unsigned long damon_pa_mar unsigned long *sz_filter_passed) { unsigned long addr, applied = 0; + struct folio *folio;
addr = r->ar.start; while (addr < r->ar.end) { - struct folio *folio = damon_get_folio(PHYS_PFN(addr)); - - if (!folio) { + folio = damon_get_folio(PHYS_PFN(addr)); + if (damon_pa_invalid_damos_folio(folio, s)) { addr += PAGE_SIZE; continue; } @@ -328,6 +340,7 @@ put_folio: addr += folio_size(folio); folio_put(folio); } + s->last_applied = folio; return applied * PAGE_SIZE; }
@@ -471,12 +484,12 @@ static unsigned long damon_pa_migrate(st { unsigned long addr, applied; LIST_HEAD(folio_list); + struct folio *folio;
addr = r->ar.start; while (addr < r->ar.end) { - struct folio *folio = damon_get_folio(PHYS_PFN(addr)); - - if (!folio) { + folio = damon_get_folio(PHYS_PFN(addr)); + if (damon_pa_invalid_damos_folio(folio, s)) { addr += PAGE_SIZE; continue; } @@ -495,6 +508,7 @@ put_folio: } applied = damon_pa_migrate_pages(&folio_list, s->target_nid); cond_resched(); + s->last_applied = folio; return applied * PAGE_SIZE; }
@@ -512,15 +526,15 @@ static unsigned long damon_pa_stat(struc { unsigned long addr; LIST_HEAD(folio_list); + struct folio *folio;
if (!damon_pa_scheme_has_filter(s)) return 0;
addr = r->ar.start; while (addr < r->ar.end) { - struct folio *folio = damon_get_folio(PHYS_PFN(addr)); - - if (!folio) { + folio = damon_get_folio(PHYS_PFN(addr)); + if (damon_pa_invalid_damos_folio(folio, s)) { addr += PAGE_SIZE; continue; } @@ -530,6 +544,7 @@ static unsigned long damon_pa_stat(struc addr += folio_size(folio); folio_put(folio); } + s->last_applied = folio; return 0; }
_
Patches currently in -mm which might be from sj@kernel.org are
mm-madvise-split-out-mmap-locking-operations-for-madvise.patch mm-madvise-split-out-madvise-input-validity-check.patch mm-madvise-split-out-madvise-behavior-execution.patch mm-madvise-remove-redundant-mmap_lock-operations-from-process_madvise.patch mm-damon-avoid-applying-damos-action-to-same-entity-multiple-times.patch