From: Muchun Song <songmuchun@bytedance.com>
Date: Thu, 5 Mar 2026 11:52:40 +0000 (+0800)
Subject: mm: workingset: prevent lruvec release in workingset_activation()
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=507382970b6ad2806fbfd72bc13e3f7c1249c4b1;p=thirdparty%2Fkernel%2Flinux.git

mm: workingset: prevent lruvec release in workingset_activation()

In the near future, a folio will no longer pin its corresponding memory
cgroup.  So an lruvec returned by folio_lruvec() could be released without
the rcu read lock or a reference to its memory cgroup.

In the current patch, the rcu read lock is employed to safeguard against
the release of the lruvec in workingset_activation().

This serves as a preparatory measure for the reparenting of the LRU pages.

Link: https://lore.kernel.org/c6130476affbba0a7d309a887c3df11e0167990b.1772711148.git.zhengqi.arch@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Allen Pais <apais@linux.microsoft.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Imran Khan <imran.f.khan@oracle.com>
Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yosry Ahmed <yosry@kernel.org>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/workingset.c b/mm/workingset.c
index 2de2a355f0f8..95d722a452e1 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -603,8 +603,11 @@ void workingset_activation(struct folio *folio)
 	 * Filter non-memcg pages here, e.g. unmap can call
 	 * mark_page_accessed() on VDSO pages.
 	 */
-	if (mem_cgroup_disabled() || folio_memcg_charged(folio))
+	if (mem_cgroup_disabled() || folio_memcg_charged(folio)) {
+		rcu_read_lock();
 		workingset_age_nonresident(folio_lruvec(folio), folio_nr_pages(folio));
+		rcu_read_unlock();
+	}
 }
 
 /*