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mm: thp: prevent memory cgroup release in folio_split_queue_lock{_irqsave}()

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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 folio_split_queue_lock{_irqsave}().

Link: https://lore.kernel.org/ca2957c0df1126b2c71b40c738018fd5255525a6.1772711148.git.zhengqi.arch@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>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Acked-by: Muchun Song <muchun.song@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: 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 <songmuchun@bytedance.com>
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:
Qi Zheng
2026-03-05 19:52:35 +08:00
committed by Andrew Morton
parent b3ca98297c
commit 681d325b23
1 changed files with 18 additions and 2 deletions
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20
mm/huge_memory.c
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@@ -1218,13 +1218,29 @@ split_queue_lock_irqsave(int nid, struct mem_cgroup *memcg, unsigned long *flags
static struct deferred_split *folio_split_queue_lock(struct folio *folio)
{
return split_queue_lock(folio_nid(folio), folio_memcg(folio));
struct deferred_split *queue;
rcu_read_lock();
queue = split_queue_lock(folio_nid(folio), folio_memcg(folio));
/*
* The memcg destruction path is acquiring the split queue lock for
* reparenting. Once you have it locked, it's safe to drop the rcu lock.
*/
rcu_read_unlock();
return queue;
}
static struct deferred_split *
folio_split_queue_lock_irqsave(struct folio *folio, unsigned long *flags)
{
return split_queue_lock_irqsave(folio_nid(folio), folio_memcg(folio), flags);
struct deferred_split *queue;
rcu_read_lock();
queue = split_queue_lock_irqsave(folio_nid(folio), folio_memcg(folio), flags);
rcu_read_unlock();
return queue;
}
static inline void split_queue_unlock(struct deferred_split *queue)