From: Muchun Song 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 Signed-off-by: Qi Zheng --- mm/workingset.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/workingset.c b/mm/workingset.c index a69cc7bf9246d..d0eb3636dcd1d 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