From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Zefan Subject: Re: [PATCH 3.4 1/2] cgroup: Take css_set_lock when calling cgroup_css_sets_empty() Date: Thu, 10 Jan 2013 10:43:09 +0800 Message-ID: <50EE2ABD.5070404@huawei.com> References: <1357743822-21707-1-git-send-email-hdegoede@redhat.com> <1357743822-21707-2-git-send-email-hdegoede@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1357743822-21707-2-git-send-email-hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Hans de Goede Cc: Tejun Heo , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On 2013/1/9 23:03, Hans de Goede wrote: > As indicated in the comment above cgroup_css_sets_empty the > css_set_lock must be hold when calling it. > > Signed-off-by: Hans de Goede > --- > kernel/cgroup.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index c908354..59e711a 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -3980,7 +3980,10 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) > /* the vfs holds both inode->i_mutex already */ > again: > mutex_lock(&cgroup_mutex); > - if (!cgroup_css_sets_empty(cgrp)) { > + read_lock(&css_set_lock); > + ret = cgroup_css_sets_empty(cgrp); This function doesn't exist in 3.4.xx kernel! It was introduced by an out-of-tree patch, and that patch introduced these two bugs (maybe more). > + read_unlock(&css_set_lock); > + if (!ret) { > mutex_unlock(&cgroup_mutex); > return -EBUSY; > } >