Commit 95093e5c authored by SeongJae Park's avatar SeongJae Park Committed by Andrew Morton
Browse files

mm/damon/core: disallow non-power of two min_region_sz on damon_start() 

Commit d8f867fa ("mm/damon: add damon_ctx->min_sz_region") introduced
a bug that allows unaligned DAMON region address ranges.  Commit
c80f46ac ("mm/damon/core: disallow non-power of two min_region_sz")
fixed it, but only for damon_commit_ctx() use case.  Still, DAMON sysfs
interface can emit non-power of two min_region_sz via damon_start().  Fix
the path by adding the is_power_of_2() check on damon_start().

The issue was discovered by sashiko [1].

Link: https://lore.kernel.org/20260411213638.77768-1-sj@kernel.org
Link: https://lore.kernel.org/20260403155530.64647-1-sj@kernel.org

 [1]
Fixes: d8f867fa ("mm/damon: add damon_ctx->min_sz_region")
Signed-off-by: default avatarSeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.18.x
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent ec05f51f

mm/damon/core.c

+5 −0
Original line number Diff line number Diff line
@@ -1368,6 +1368,11 @@ int damon_start(struct damon_ctx **ctxs, int nr_ctxs, bool exclusive) 
	int i;

	int err = 0;



	for (i = 0; i < nr_ctxs; i++) {

		if (!is_power_of_2(ctxs[i]->min_region_sz))

			return -EINVAL;

	}



	mutex_lock(&damon_lock);

	if ((exclusive && nr_running_ctxs) ||

			(!exclusive && running_exclusive_ctxs)) {