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mm: memcontrol: prevent memory cgroup release in get_mem_cgroup_from_folio()

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In the near future, a folio will no longer pin its corresponding memory
cgroup.  To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.

In the current patch, the rcu read lock is employed to safeguard against
the release of the memory cgroup in get_mem_cgroup_from_folio().

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

Link: https://lore.kernel.org/a5a64c6173a566bd21534606aeaaa9220cb1366d.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: 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: Johannes Weiner <hannes@cmpxchg.org>
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>
This commit is contained in:
Muchun Song 2026-03-05 19:52:26 +08:00 committed by Andrew Morton
parent d5aa8c1d13
commit af86590786
1 changed files with 7 additions and 3 deletions
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10
mm/memcontrol.c
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@ -996,14 +996,18 @@ struct mem_cgroup *get_mem_cgroup_from_current(void)
*/
struct mem_cgroup *get_mem_cgroup_from_folio(struct folio *folio)
{
struct mem_cgroup *memcg = folio_memcg(folio);
struct mem_cgroup *memcg;
if (mem_cgroup_disabled())
return NULL;
if (!folio_memcg_charged(folio))
return root_mem_cgroup;
rcu_read_lock();
if (!memcg || WARN_ON_ONCE(!css_tryget(&memcg->css)))
memcg = root_mem_cgroup;
do {
memcg = folio_memcg(folio);
} while (unlikely(!css_tryget(&memcg->css)));
rcu_read_unlock();
return memcg;
}