* [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems()
@ 2022-08-23 5:41 Jing-Ting Wu
2022-08-23 7:33 ` Mukesh Ojha
2022-08-23 18:12 ` Tejun Heo
0 siblings, 2 replies; 4+ messages in thread
From: Jing-Ting Wu @ 2022-08-23 5:41 UTC (permalink / raw)
To: Michal Koutný,
Tejun Heo, Zefan Li, Johannes Weiner, Matthias Brugger
Cc: Jonathan.JMChen, Lixiong.Liu, wsd_upstream, Wenju.Xu,
Jing-Ting Wu, Jing-Ting Wu, cgroups, linux-kernel,
linux-arm-kernel, linux-mediatek
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@mediatek.com>
Suggested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Jing-Ting Wu <jing-ting.wu@mediatek.com>
Tested-by: Jing-Ting Wu <jing-ting.wu@mediatek.com>
Link: https://lore.kernel.org/linux-arm-kernel/d8f0bc5e2fb6ed259f9334c83279b4c011283c41.camel@mediatek.com/T/
---
kernel/cgroup/cgroup.c | 1 +
1 file changed, 1 insertion(+)
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);
}
--
2.18.0
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems()
2022-08-23 5:41 [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems() Jing-Ting Wu
@ 2022-08-23 7:33 ` Mukesh Ojha
2022-08-23 18:12 ` Tejun Heo
1 sibling, 0 replies; 4+ messages in thread
From: Mukesh Ojha @ 2022-08-23 7:33 UTC (permalink / raw)
To: Jing-Ting Wu, Michal Koutný,
Tejun Heo, Zefan Li, Johannes Weiner, Matthias Brugger
Cc: Jonathan.JMChen, Lixiong.Liu, wsd_upstream, Wenju.Xu, cgroups,
linux-kernel, linux-arm-kernel, linux-mediatek
On 8/23/2022 11:11 AM, Jing-Ting Wu wrote:
> 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@mediatek.com>
> Suggested-by: Michal Koutný <mkoutny@suse.com>
> Signed-off-by: Jing-Ting Wu <jing-ting.wu@mediatek.com>
> Tested-by: Jing-Ting Wu <jing-ting.wu@mediatek.com>
> Link: https://lore.kernel.org/linux-arm-kernel/d8f0bc5e2fb6ed259f9334c83279b4c011283c41.camel@mediatek.com/T/
> ---
> kernel/cgroup/cgroup.c | 1 +
> 1 file changed, 1 insertion(+)
>
> 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);
> }
Good catch.
Acked-by: Mukesh Ojha <quic_mojha@quicinc.com>
-Mukesh
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems()
2022-08-23 5:41 [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems() Jing-Ting Wu
2022-08-23 7:33 ` Mukesh Ojha
@ 2022-08-23 18:12 ` Tejun Heo
1 sibling, 0 replies; 4+ messages in thread
From: Tejun Heo @ 2022-08-23 18:12 UTC (permalink / raw)
To: Jing-Ting Wu
Cc: Michal Koutný,
Zefan Li, Johannes Weiner, Matthias Brugger, Jonathan.JMChen,
Lixiong.Liu, wsd_upstream, Wenju.Xu, cgroups, linux-kernel,
linux-arm-kernel, linux-mediatek
On Tue, Aug 23, 2022 at 01:41:46PM +0800, Jing-Ting Wu wrote:
> 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@mediatek.com>
> Suggested-by: Michal Koutný <mkoutny@suse.com>
> Signed-off-by: Jing-Ting Wu <jing-ting.wu@mediatek.com>
> Tested-by: Jing-Ting Wu <jing-ting.wu@mediatek.com>
> Link: https://lore.kernel.org/linux-arm-kernel/d8f0bc5e2fb6ed259f9334c83279b4c011283c41.camel@mediatek.com/T/
Applied to cgroup/for-6.0-fixes w/ stable tag added.
Thanks.
--
tejun
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^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems()
@ 2022-08-23 5:09 Jing-Ting Wu
0 siblings, 0 replies; 4+ messages in thread
From: Jing-Ting Wu @ 2022-08-23 5:09 UTC (permalink / raw)
To: Michal Koutný,
Tejun Heo, Zefan Li, Johannes Weiner, Matthias Brugger
Cc: Jonathan.JMChen, Lixiong.Liu, wsd_upstream, Wenju.Xu,
Jing-Ting Wu, cgroups, linux-kernel, linux-arm-kernel,
linux-mediatek
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 --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);
}
--
2.18.0
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-08-23 18:13 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2022-08-23 5:41 [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems() Jing-Ting Wu
2022-08-23 7:33 ` Mukesh Ojha
2022-08-23 18:12 ` Tejun Heo
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