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From: Tejun Heo <tj@kernel.org>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Zefan Li <lizefan@huawei.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	jweiner@fb.com, LKML <linux-kernel@vger.kernel.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	syzkaller <syzkaller@googlegroups.com>
Subject: Re: cgroup: WARNING in cgroup_kill_sb
Date: Mon, 6 Mar 2017 16:55:15 -0500	[thread overview]
Message-ID: <20170306215515.GH26127@htj.duckdns.org> (raw)
In-Reply-To: <CACT4Y+Y9d3FwPWR+pVNMU1uho9GYwJ6gfJ7AjE+NXYoA0py4ow@mail.gmail.com>

Hello, Dmitry.

Can you please see whether the following patch resolves the issue?
I'm a bit nervous about it ending up in circular dependency, but I
*think* it should be okay.

Thanks.

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 0125589..9c40421 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1820,6 +1820,8 @@ static void cgroup_kill_sb(struct super_block *sb)
 	struct kernfs_root *kf_root = kernfs_root_from_sb(sb);
 	struct cgroup_root *root = cgroup_root_from_kf(kf_root);
 
+	mutex_lock(&cgroup_mutex);
+
 	/*
 	 * If @root doesn't have any mounts or children, start killing it.
 	 * This prevents new mounts by disabling percpu_ref_tryget_live().
@@ -1834,6 +1836,8 @@ static void cgroup_kill_sb(struct super_block *sb)
 		percpu_ref_kill(&root->cgrp.self.refcnt);
 
 	kernfs_kill_sb(sb);
+
+	mutex_unlock(&cgroup_mutex);
 }
 
 struct file_system_type cgroup_fs_type = {

  reply	other threads:[~2017-03-06 21:55 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-02 19:15 cgroup: WARNING in cgroup_kill_sb Dmitry Vyukov
2017-03-06 21:55 ` Tejun Heo [this message]
2017-03-07  9:11   ` Dmitry Vyukov
2017-03-07 19:45     ` Tejun Heo
2017-03-07 19:52       ` Dmitry Vyukov
2017-03-09  9:24 ` Zefan Li
2017-03-09  9:48   ` Dmitry Vyukov

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