Commit 763f4fb7 authored by Jing-Ting Wu's avatar Jing-Ting Wu Committed by Tejun Heo
Browse files

cgroup: Fix race condition at rebind_subsystems() 



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.

Reported-by: default avatarJing-Ting Wu <jing-ting.wu@mediatek.com>
Suggested-by: default avatarMichal Koutný <mkoutny@suse.com>
Signed-off-by: default avatarJing-Ting Wu <jing-ting.wu@mediatek.com>
Tested-by: default avatarJing-Ting Wu <jing-ting.wu@mediatek.com>
Link: https://lore.kernel.org/linux-arm-kernel/d8f0bc5e2fb6ed259f9334c83279b4c011283c41.camel@mediatek.com/T/


Acked-by: default avatarMukesh Ojha <quic_mojha@quicinc.com>
Fixes: a7df69b8 ("cgroup: rstat: support cgroup1")
Cc: stable@vger.kernel.org # v5.13+
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 4f7e7236

kernel/cgroup/cgroup.c

+1 −0
Original line number Diff line number Diff line
@@ -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);

		}