mm-damon-reclaim-validate-min_region_size-to-be-power-of-2.patch removed from -mm tree

The quilt patch titled
Subject: mm/damon/reclaim: validate min_region_size to be power of 2
has been removed from the -mm tree. Its filename was
mm-damon-reclaim-validate-min_region_size-to-be-power-of-2.patch

This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Liew Rui Yan <[email protected]>
Subject: mm/damon/reclaim: validate min_region_size to be power of 2
Date: Fri, 1 May 2026 09:37:50 +0800

Problem
=======
When a user sets an invalid 'addr_unit' (e.g., 3) via DAMON_RECLAIM, 'min_region_sz' becomes a non-power-of-2 value. While damon_commit_ctx() correctly detects this and returns -EINVAL, it sets the 'maybe_corrupted' flag during this process.

This flag causes the running kdamond to terminate. While the termination is a safety measure, it is suboptimal in this case because the error is just a simple invalid input from the user, which shouldn't neccessitate stopping the kdamond.

Reproduction
============
1. Enable DAMON_RECLAIM
2. Set addr_unit=3
3. Commit inputs via 'commit_inputs'
4. Observe kdamond termination

Solution
========
Add an early validation in damon_reclaim_apply_parameters() to check 'min_region_sz' before any state change occurs. If it is non-power-of-2, return -EINVAL immediately, preventing 'maybe_corrupted' from being set.

---

 mm/damon/reclaim.c |    5 +++++
 1 file changed, 5 insertions(+)

@@ -210,6 +210,11 @@ static int damon_reclaim_apply_parameter
 	param_ctx->addr_unit = addr_unit;
 	param_ctx->min_region_sz = max(DAMON_MIN_REGION_SZ / addr_unit, 1);
 
+	if (!is_power_of_2(param_ctx->min_region_sz)) {
+		err = -EINVAL;
+		goto out;
+	}
+
 	if (!damon_reclaim_mon_attrs.aggr_interval) {
 		err = -EINVAL;
 		goto out;

_

Patches currently in -mm which might be from [email protected] are