mm/damon/core: copy nr_accesses when splitting region

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>

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 6262d55904e744a4a41431127266971eb5ee3d8b..ce1562783e7e5df9941cd66e8eaf57db90f176de 100644 (file)
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1225,6 +1225,7 @@ static void damon_split_region_at(struct damon_target *t,
        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);
 }