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From: Jing-Ting Wu <Jing-Ting.Wu@mediatek.com>
To: "Michal Koutný" <mkoutny@suse.com>, "Tejun Heo" <tj@kernel.org>,
	"Zefan Li" <lizefan.x@bytedance.com>,
	"Johannes Weiner" <hannes@cmpxchg.org>,
	"Matthias Brugger" <matthias.bgg@gmail.com>
Cc: <Jonathan.JMChen@mediatek.com>, <Lixiong.Liu@mediatek.com>,
	<wsd_upstream@mediatek.com>, <Wenju.Xu@mediatek.com>,
	Jing-Ting Wu <Jing-Ting.Wu@mediatek.com>,
	<cgroups@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-mediatek@lists.infradead.org>
Subject: [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems()
Date: Tue, 23 Aug 2022 13:09:41 +0800	[thread overview]
Message-ID: <20220823050943.28619-1-Jing-Ting.Wu@mediatek.com> (raw)

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


WARNING: multiple messages have this Message-ID (diff)
From: Jing-Ting Wu <Jing-Ting.Wu@mediatek.com>
To: "Michal Koutný" <mkoutny@suse.com>, "Tejun Heo" <tj@kernel.org>,
	"Zefan Li" <lizefan.x@bytedance.com>,
	"Johannes Weiner" <hannes@cmpxchg.org>,
	"Matthias Brugger" <matthias.bgg@gmail.com>
Cc: <Jonathan.JMChen@mediatek.com>, <Lixiong.Liu@mediatek.com>,
	<wsd_upstream@mediatek.com>, <Wenju.Xu@mediatek.com>,
	Jing-Ting Wu <Jing-Ting.Wu@mediatek.com>,
	<cgroups@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-mediatek@lists.infradead.org>
Subject: [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems()
Date: Tue, 23 Aug 2022 13:09:41 +0800	[thread overview]
Message-ID: <20220823050943.28619-1-Jing-Ting.Wu@mediatek.com> (raw)

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


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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Jing-Ting Wu <Jing-Ting.Wu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
To: "Michal Koutný" <mkoutny-IBi9RG/b67k@public.gmane.org>,
	"Tejun Heo" <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	"Zefan Li" <lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>,
	"Johannes Weiner"
	<hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
	"Matthias Brugger"
	<matthias.bgg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Jonathan.JMChen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org,
	Lixiong.Liu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org,
	wsd_upstream-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org,
	Wenju.Xu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org,
	Jing-Ting Wu
	<Jing-Ting.Wu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	linux-mediatek-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems()
Date: Tue, 23 Aug 2022 13:09:41 +0800	[thread overview]
Message-ID: <20220823050943.28619-1-Jing-Ting.Wu@mediatek.com> (raw)

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 Koutn√Ω <mkoutny-IBi9RG/b67k@public.gmane.org>
Signed-off-by: Jing-Ting Wu <Jing-Ting.Wu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
---
 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


             reply	other threads:[~2022-08-23  5:11 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-23  5:09 Jing-Ting Wu [this message]
2022-08-23  5:09 ` [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems() Jing-Ting Wu
2022-08-23  5:09 ` Jing-Ting Wu
2022-08-23  5:41 Jing-Ting Wu
2022-08-23  5:41 ` Jing-Ting Wu
2022-08-23  5:41 ` Jing-Ting Wu
2022-08-23  7:33 ` Mukesh Ojha
2022-08-23  7:33   ` Mukesh Ojha
2022-08-23  7:33   ` Mukesh Ojha
2022-08-23 18:12 ` Tejun Heo
2022-08-23 18:12   ` Tejun Heo

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