+ mm-damon-core-copy-nr_accesses-when-splitting-region.patch added to mm-hotfixes-unstable branch

+ mm-damon-core-copy-nr_accesses-when-splitting-region.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/damon/core: copy nr_accesses when splitting region
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-damon-core-copy-nr_accesses-when-splitting-region.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-core-copy-nr_accesses-when-splitting-region.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: SeongJae Park <sj@kernel.org>
Subject: mm/damon/core: copy nr_accesses when splitting region
Date: Sun, 19 Nov 2023 17:15:28 +0000

Regions split function ('damon_split_region_at()') is called at the
beginning of an aggregation interval, and when DAMOS applying the actions
and charging quota.  Because 'nr_accesses' fields of all regions are reset
at the beginning of each aggregation interval, and DAMOS was applying the
action at the end of each aggregation interval, there was no need to copy
the 'nr_accesses' field to the split-out region.

However, commit 42f994b71404 ("mm/damon/core: implement scheme-specific
apply interval") made DAMOS applies action on its own timing interval. 
Hence, 'nr_accesses' should also copied to split-out regions, but the
commit didn't.  Fix it by copying it.

Link: https://lkml.kernel.org/r/20231119171529.66863-1-sj@kernel.org
Fixes: 42f994b71404 ("mm/damon/core: implement scheme-specific apply interval")
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/damon/core.c |    1 +
 1 file changed, 1 insertion(+)

--- a/mm/damon/core.c~mm-damon-core-copy-nr_accesses-when-splitting-region
+++ a/mm/damon/core.c
@@ -1225,6 +1225,7 @@ static void damon_split_region_at(struct
 	new->age = r->age;
 	new->last_nr_accesses = r->last_nr_accesses;
 	new->nr_accesses_bp = r->nr_accesses_bp;
+	new->nr_accesses = r->nr_accesses;
 
 	damon_insert_region(new, r, damon_next_region(r), t);
 }
_

Patches currently in -mm which might be from sj@kernel.org are

mm-damon-core-copy-nr_accesses-when-splitting-region.patch