This is a note to let you know that I've just added the patch titled
cgroup: Fix race condition at rebind_subsystems()
to the 5.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cgroup-fix-race-condition-at-rebind_subsystems.patch
and it can be found in the queue-5.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 763f4fb76e24959c370cdaa889b2492ba6175580 Mon Sep 17 00:00:00 2001
From: Jing-Ting Wu <Jing-Ting.Wu@xxxxxxxxxxxx>
Date: Tue, 23 Aug 2022 13:41:46 +0800
Subject: cgroup: Fix race condition at rebind_subsystems()
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From: Jing-Ting Wu <Jing-Ting.Wu@xxxxxxxxxxxx>
commit 763f4fb76e24959c370cdaa889b2492ba6175580 upstream.
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: Jing-Ting Wu <jing-ting.wu@xxxxxxxxxxxx>
Suggested-by: Michal Koutný <mkoutny@xxxxxxxx>
Signed-off-by: Jing-Ting Wu <jing-ting.wu@xxxxxxxxxxxx>
Tested-by: Jing-Ting Wu <jing-ting.wu@xxxxxxxxxxxx>
Link: https://lore.kernel.org/linux-arm-kernel/d8f0bc5e2fb6ed259f9334c83279b4c011283c41.camel@xxxxxxxxxxxx/T/
Acked-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
Fixes: a7df69b81aac ("cgroup: rstat: support cgroup1")
Cc: stable@xxxxxxxxxxxxxxx # v5.13+
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/cgroup/cgroup.c | 1 +
1 file changed, 1 insertion(+)
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1811,6 +1811,7 @@ int rebind_subsystems(struct cgroup_root
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);
}
Patches currently in stable-queue which might be from Jing-Ting.Wu@xxxxxxxxxxxx are
queue-5.19/cgroup-fix-race-condition-at-rebind_subsystems.patch
