[merged mm-stable] mm-damon-lru_sort-validate-min_region_size-to-be-power-of-2.patch removed from -mm tree

[merged mm-stable] mm-damon-lru_sort-validate-min_region_size-to-be-power-of-2.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/damon/lru_sort: validate min_region_size to be power of 2
has been removed from the -mm tree.  Its filename was
     mm-damon-lru_sort-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 <aethernet65535@gmail.com>
Subject: mm/damon/lru_sort: validate min_region_size to be power of 2
Date: Fri, 1 May 2026 09:37:49 +0800

Patch series "mm/damon: validate min_region_size to be power of 2", v5.

Problem
=======
When a user sets an invalid 'addr_unit' (e.g., 3) via DAMON_LRU_SORT or
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.

Solution
========
Add an early validation in damon_lru_sort_apply_parameters() and
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.

Patch 1 fixes the issue for DAMON_LRU_SORT.
Patch 2 fixes the issue for DAMON_RECLAIM.


This patch (of 2):

Problem
=======
When a user sets an invalid 'addr_unit' (e.g., 3) via DAMON_LRU_SORT,
'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_LRU_SORT
2. Set addr_unit=3
3. Commit inputs via 'commit_inputs'
4. Observe kdamond termination

Solution
========
Add an early validation in damon_lru_sort_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.

Link: https://lore.kernel.org/20260501013750.71704-1-aethernet65535@gmail.com
Link: https://lore.kernel.org/20260501013750.71704-2-aethernet65535@gmail.com
Signed-off-by: Liew Rui Yan <aethernet65535@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

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

--- a/mm/damon/lru_sort.c~mm-damon-lru_sort-validate-min_region_size-to-be-power-of-2
+++ a/mm/damon/lru_sort.c
@@ -286,6 +286,11 @@ static int damon_lru_sort_apply_paramete
 	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_lru_sort_mon_attrs.sample_interval) {
 		err = -EINVAL;
 		goto out;
_

Patches currently in -mm which might be from aethernet65535@gmail.com are