From: Muchun Song <songmuchun@bytedance.com>
In the near future, a folio will no longer pin its corresponding
memory cgroup. So an lruvec returned by folio_lruvec() could be
released without the rcu read lock or a reference to its memory
cgroup.
In the current patch, the rcu read lock is employed to safeguard
against the release of the lruvec in workingset_activation().
This serves as a preparatory measure for the reparenting of the
LRU pages.
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>
---
mm/workingset.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/workingset.c b/mm/workingset.c
index 427ca1a5625e8..d6484f7a3ad28 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -595,8 +595,11 @@ void workingset_activation(struct folio *folio)
* Filter non-memcg pages here, e.g. unmap can call
* mark_page_accessed() on VDSO pages.
*/
- if (mem_cgroup_disabled() || folio_memcg_charged(folio))
+ if (mem_cgroup_disabled() || folio_memcg_charged(folio)) {
+ rcu_read_lock();
workingset_age_nonresident(folio_lruvec(folio), folio_nr_pages(folio));
+ rcu_read_unlock();
+ }
}
/*
--
2.20.1