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mm/damon/core: add damon_merge_two_regions() debug_sanity check

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A data corruption could cause damon_merge_two_regions() creating zero
length DAMON regions.  Add a sanity check for that under
CONFIG_DAMON_DEBUG_SANITY.

Link: https://lkml.kernel.org/r/20260306152914.86303-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
SeongJae Park 2026-03-06 07:29:08 -08:00 committed by Andrew Morton
parent 242a764abe
commit 0bb7682fdb
1 changed files with 16 additions and 0 deletions
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16
mm/damon/core.c
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@ -2475,6 +2475,21 @@ static void kdamond_apply_schemes(struct damon_ctx *c)
mutex_unlock(&c->walk_control_lock);
}
#ifdef CONFIG_DAMON_DEBUG_SANITY
static void damon_verify_merge_two_regions(
struct damon_region *l, struct damon_region *r)
{
/* damon_merge_two_regions() may created incorrect left region */
WARN_ONCE(l->ar.start >= l->ar.end, "l: %lu-%lu, r: %lu-%lu\n",
l->ar.start, l->ar.end, r->ar.start, r->ar.end);
}
#else
static void damon_verify_merge_two_regions(
struct damon_region *l, struct damon_region *r)
{
}
#endif
/*
* Merge two adjacent regions into one region
*/
@ -2488,6 +2503,7 @@ static void damon_merge_two_regions(struct damon_target *t,
l->nr_accesses_bp = l->nr_accesses * 10000;
l->age = (l->age * sz_l + r->age * sz_r) / (sz_l + sz_r);
l->ar.end = r->ar.end;
damon_verify_merge_two_regions(l, r);
damon_destroy_region(r, t);
}