From 260d70819c37cf59383286f8dc6566eaa32776bb Mon Sep 17 00:00:00 2001 From: Altan Hacigumus Date: Tue, 3 Feb 2026 19:35:53 -0800 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(). Also, since memcg_kmem_online() and shrinker flags cannot change dynamically, remove the shrinker from the bitmap to avoid unnecessary future scans. Link: https://lkml.kernel.org/r/20260204033553.50039-1-ahacigu.linux@gmail.com Fixes: 50d09da8e119 ("mm: shrinker: make memcg slab shrink lockless") Signed-off-by: Altan Hacigumus Acked-by: Qi Zheng Link: https://lore.kernel.org/r/20260203073757.135088-1-ahacigu.linux@gmail.com Reviewed-by: Muchun Song Cc: Dave Chinner Cc: Roman Gushchin Signed-off-by: Andrew Morton --- mm/shrinker.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/shrinker.c b/mm/shrinker.c index 7b61fc0ee78f..94646ee0af63 100644 --- a/mm/shrinker.c +++ b/mm/shrinker.c @@ -544,8 +544,11 @@ 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)) { + clear_bit(offset, unit->map); + shrinker_put(shrinker); continue; + } ret = do_shrink_slab(&sc, shrinker, priority); if (ret == SHRINK_EMPTY) {