From mboxrd@z Thu Jan 1 00:00:00 1970 From: KAMEZAWA Hiroyuki Subject: [RFC][PATCH 8/9 v2] cgroup: avoid creating new cgroup under a cgroup being destroyed Date: Fri, 27 Apr 2012 15:04:14 +0900 Message-ID: <4F9A36DE.30301@jp.fujitsu.com> References: <4F9A327A.6050409@jp.fujitsu.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4F9A327A.6050409-+CUm20s59erQFUHtdCDX3A@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Linux Kernel Cc: "linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org" , "cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Michal Hocko , Johannes Weiner , Frederic Weisbecker , Glauber Costa , Tejun Heo , Han Ying , "Aneesh Kumar K.V" , Andrew Morton , kamezawa.hiroyuki-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org When ->pre_destroy() is called, it should be guaranteed that new child cgroup is not created under a cgroup, where pre_destroy() is running. If not, ->pre_destroy() must check children and return -EBUSY, which causes warning. Signed-off-by: KAMEZAWA Hiroyuki --- kernel/cgroup.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 7a3076b..003ceed 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3970,6 +3970,15 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, mutex_lock(&cgroup_mutex); + /* + * prevent making child cgroup when ->pre_destroy() is running. + */ + if (test_bit(CGRP_WAIT_ON_RMDIR, &parent->flags)) { + mutex_unlock(&cgroup_mutex); + atomic_dec(&sb->s_active); + return -EBUSY; + } + init_cgroup_housekeeping(cgrp); cgrp->parent = parent; -- 1.7.4.1