Commit 681d325b authored by Qi Zheng's avatar Qi Zheng Committed by Andrew Morton
Browse files

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

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: default avatarQi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: default avatarHarry Yoo <harry.yoo@oracle.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarShakeel Butt <shakeel.butt@linux.dev>
Acked-by: default avatarDavid Hildenbrand (Red Hat) <david@kernel.org>
Acked-by: default avatarMuchun 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent b3ca9829

mm/huge_memory.c

+18 −2
Original line number Diff line number Diff line
@@ -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)