diff mbox series

[1/1] cgroup: Fix race condition at rebind_subsystems()

Message ID 20220823050943.28619-1-Jing-Ting.Wu@mediatek.com (mailing list archive)
State New, archived
Headers show
Series [1/1] cgroup: Fix race condition at rebind_subsystems() | expand

Commit Message

Jing-Ting Wu Aug. 23, 2022, 5:09 a.m. UTC 
Root cause:
The rebind_subsystems() is no lock held when move css object from A
list to B list,then let B's head be treated as css node at
list_for_each_entry_rcu().

Solution:
Add grace period before invalidating the removed rstat_css_node.

Suggested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Jing-Ting Wu <Jing-Ting.Wu@mediatek.com>
---
 kernel/cgroup/cgroup.c | 1 +
 1 file changed, 1 insertion(+)
diff mbox series

Patch

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index ffaccd6373f1..0d0c959966ed 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1820,6 +1820,7 @@  int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
 
 		if (ss->css_rstat_flush) {
 			list_del_rcu(&css->rstat_css_node);
+			synchronize_rcu();
 			list_add_rcu(&css->rstat_css_node,
 				     &dcgrp->rstat_css_list);
 		}