From: Yu Kuai <yukuai3@huawei.com>

Prepare to convert protecting blkcg with blkcg_mutex instead of
queue_lock.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 mm/page_io.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/mm/page_io.c b/mm/page_io.c
index a2056a5ecb13..4f4cc9370573 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -313,8 +313,13 @@ static void bio_associate_blkg_from_page(struct bio *bio, struct folio *folio)
 
 	rcu_read_lock();
 	css = cgroup_e_css(memcg->css.cgroup, &io_cgrp_subsys);
-	bio_associate_blkg_from_css(bio, css);
+	if (!css || !css_tryget_online(css))
+		css = NULL;
 	rcu_read_unlock();
+
+	bio_associate_blkg_from_css(bio, css);
+	if (css)
+		css_put(css);
 }
 #else
 #define bio_associate_blkg_from_page(bio, folio)		do { } while (0)
-- 
2.51.0