From: Muchun Song 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 function get_mem_cgroup_from_folio() is employed to safeguard against the release of the memory cgroup. This serves as a preparatory measure for the reparenting of the LRU pages. Signed-off-by: Muchun Song Signed-off-by: Qi Zheng Reviewed-by: Harry Yoo --- fs/buffer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index fd53b806ab7eb..4552d9cab0dbd 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -925,8 +925,7 @@ struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size, long offset; struct mem_cgroup *memcg, *old_memcg; - /* The folio lock pins the memcg */ - memcg = folio_memcg(folio); + memcg = get_mem_cgroup_from_folio(folio); old_memcg = set_active_memcg(memcg); head = NULL; @@ -947,6 +946,7 @@ struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size, } out: set_active_memcg(old_memcg); + mem_cgroup_put(memcg); return head; /* * In case anything failed, we just free everything we got. -- 2.20.1