Commit 3dece834 authored Oct 01, 2009 by KAMEZAWA Hiroyuki Committed by Linus Torvalds Oct 01, 2009

cgroup: catch bad css refcnt at css_put



__css_put() doesn't check a bug as refcnt goes to minus.
I think it should be caught. This patch adds a check for it.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 26251eaf

kernel/cgroup.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -3708,8 +3708,10 @@ static void check_for_release(struct cgroup *cgrp)
		void __css_put(struct cgroup_subsys_state *css)
		{
		struct cgroup *cgrp = css->cgroup;
		int val;
		rcu_read_lock();
		if (atomic_dec_return(&css->refcnt) == 1) {
		val = atomic_dec_return(&css->refcnt);
		if (val == 1) {
		if (notify_on_release(cgrp)) {
		set_bit(CGRP_RELEASABLE, &cgrp->flags);
		check_for_release(cgrp);
		@@ -3717,6 +3719,7 @@ void __css_put(struct cgroup_subsys_state *css)
		cgroup_wakeup_rmdir_waiter(cgrp);
		}
		rcu_read_unlock();
		WARN_ON_ONCE(val < 1);
		}

		/*