diff mbox series

[RFC,23/28] mm: workingset: prevent lruvec release in workingset_activation()

Message ID 20250415024532.26632-24-songmuchun@bytedance.com (mailing list archive)
State New
Headers show
Series Eliminate Dying Memory Cgroup | expand

Commit Message

Muchun Song April 15, 2025, 2:45 a.m. UTC 
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>
---
 mm/workingset.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/mm/workingset.c b/mm/workingset.c
index ef89d18cb8cf..ec625eb7db69 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();
+	}
 }
 
 /*