Commit cf4d6ad5 authored by Qi Zheng's avatar Qi Zheng Committed by Andrew Morton
Browse files

mm: zswap: prevent memory cgroup release in zswap_compress() 

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 zswap_compress().

Link: https://lore.kernel.org/340f315050fb8a67caaf01b4836d4f38a41cf1a8.1772711148.git.zhengqi.arch@bytedance.com


Signed-off-by: default avatarQi Zheng <zhengqi.arch@bytedance.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarShakeel Butt <shakeel.butt@linux.dev>
Acked-by: default avatarMuchun Song <muchun.song@linux.dev>
Reviewed-by: default avatarHarry Yoo <harry.yoo@oracle.com>
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 <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 681d325b

mm/zswap.c

+3 −0
Original line number Diff line number Diff line
@@ -893,11 +893,14 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry, 
	 * to the active LRU list in the case.

	 */

	if (comp_ret || !dlen || dlen >= PAGE_SIZE) {

		rcu_read_lock();

		if (!mem_cgroup_zswap_writeback_enabled(

					folio_memcg(page_folio(page)))) {

			rcu_read_unlock();

			comp_ret = comp_ret ? comp_ret : -EINVAL;

			goto unlock;

		}

		rcu_read_unlock();

		comp_ret = 0;

		dlen = PAGE_SIZE;

		dst = kmap_local_page(page);