From mboxrd@z Thu Jan 1 00:00:00 1970 From: KAMEZAWA Hiroyuki Subject: [RFC][PATCH 7/9 v2] cgroup: avoid attaching task to a cgroup under rmdir() Date: Fri, 27 Apr 2012 15:02:22 +0900 Message-ID: <4F9A366E.9020307@jp.fujitsu.com> References: <4F9A327A.6050409@jp.fujitsu.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4F9A327A.6050409@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Linux Kernel Cc: "linux-mm@kvack.org" , "cgroups@vger.kernel.org" , Michal Hocko , Johannes Weiner , Frederic Weisbecker , Glauber Costa , Tejun Heo , Han Ying , "Aneesh Kumar K.V" , Andrew Morton , kamezawa.hiroyuki@gmail.com attach_task() is done under cgroup_mutex() but ->pre_destroy() callback in rmdir() isn't called under cgroup_mutex(). It's better to avoid attaching a task to a cgroup which is under pre_destroy(). Considering memcg, the attached task may increase resource usage after memcg's pre_destroy() confirms that memcg is empty. This is not good. Signed-off-by: KAMEZAWA Hiroyuki --- kernel/cgroup.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index ad8eae5..7a3076b 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1953,6 +1953,9 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) if (cgrp == oldcgrp) return 0; + if (test_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags)) + return -EBUSY; + tset.single.task = tsk; tset.single.cgrp = oldcgrp; @@ -4181,7 +4184,6 @@ again: mutex_unlock(&cgroup_mutex); return -EBUSY; } - mutex_unlock(&cgroup_mutex); /* * In general, subsystem has no css->refcnt after pre_destroy(). But @@ -4193,6 +4195,7 @@ again: * and css_tryget() and cgroup_wakeup_rmdir_waiter() implementation. */ set_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); + mutex_unlock(&cgroup_mutex); /* * Call pre_destroy handlers of subsys. Notify subsystems -- 1.7.4.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org