Commit 95093e5cb4c5 for kernel

commit 95093e5cb4c5b50a5b1a4b79f2942b62744bd66a
Author: SeongJae Park <sj@kernel.org>
Date:   Sat Apr 11 14:36:36 2026 -0700

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

    Commit d8f867fa0825 ("mm/damon: add damon_ctx->min_sz_region") introduced
    a bug that allows unaligned DAMON region address ranges.  Commit
    c80f46ac228b ("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: d8f867fa0825 ("mm/damon: add damon_ctx->min_sz_region")
    Signed-off-by: SeongJae Park <sj@kernel.org>
    Cc: <stable@vger.kernel.org> # 6.18.x
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 3703f62a876b..c107d74c77e7 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -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)) {