linux-kernel - [PATCH] mm/shrinker: Fix refcount leak in shrink_slab

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Message-ID: <20260203073757.135088-1-ahacigu.linux@gmail.com>
Date: Mon,  2 Feb 2026 23:37:57 -0800
From: Altan Hacigumus <ahacigu.linux@...il.com>
To: akpm@...ux-foundation.org,
	david@...morbit.com
Cc: ahacigu.linux@...il.com,
	zhengqi.arch@...edance.com,
	roman.gushchin@...ux.dev,
	muchun.song@...ux.dev,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] mm/shrinker: Fix refcount leak in shrink_slab_memcg()

When kmem is disabled for memcg, slab-backed shrinkers are skipped.
However, shrink_slab_memcg() doesn't drop the reference acquired via
shrinker_try_get() before continuing.

Add the missing shrinker_put().

Fixes: 50d09da8e119 ("mm: shrinker: make memcg slab shrink lockless")

Signed-off-by: Altan Hacigumus <ahacigu.linux@...il.com>
---
 mm/shrinker.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/shrinker.c b/mm/shrinker.c
index 4a93fd433689..d0be120488b4 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c
@@ -544,8 +544,10 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
 
 			/* Call non-slab shrinkers even though kmem is disabled */
 			if (!memcg_kmem_online() &&
-			    !(shrinker->flags & SHRINKER_NONSLAB))
+			    !(shrinker->flags & SHRINKER_NONSLAB)) {
+				shrinker_put(shrinker);
 				continue;
+			}
 
 			ret = do_shrink_slab(&sc, shrinker, priority);
 			if (ret == SHRINK_EMPTY) {
-- 
2.43.0