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. Signed-off-by: SeongJae Park --- mm/damon/core.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 2b5aed89d449d..8a3738a17cdd9 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -2473,6 +2473,21 @@ 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 */ @@ -2486,6 +2501,7 @@ 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); } -- 2.47.3