From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
Cc: "Kirill A. Shutemov"
<kirill-oKw7cIdHH8eLwutG50LtGA@public.gmane.org>,
LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Cgroups <cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH v3] cgroup: fix cgroup_rmdir() vs close(eventfd) race
Date: Mon, 18 Feb 2013 09:17:56 -0800 [thread overview]
Message-ID: <20130218171756.GE17414@htj.dyndns.org> (raw)
In-Reply-To: <512208CE.8000003-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
On Mon, Feb 18, 2013 at 06:56:14PM +0800, Li Zefan wrote:
> commit 205a872bd6f9a9a09ef035ef1e90185a8245cc58 ("cgroup: fix lockdep
> warning for event_control") solved a deadlock by introducing a new
> bug.
>
> Move cgrp->event_list to a temporary list doesn't mean you can traverse
> this list locklessly, because at the same time cgroup_event_wake() can
> be called and remove the event from the list. The result of this race
> is disastrous.
>
> We adopt the way how kvm irqfd code implements race-free event removal,
> which is now described in the comments in cgroup_event_wake().
>
> v3:
> - call eventfd_signal() no matter it's eventfd close or cgroup removal
> that removes the cgroup event.
>
> Acked-by: Kirill A. Shutemov <kirill-oKw7cIdHH8eLwutG50LtGA@public.gmane.org>
> Signed-off-by: Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
Dropped v2 and applied this one to cgroup/for-3.9.
Thanks.
--
tejun
prev parent reply other threads:[~2013-02-18 17:17 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-18 10:56 [PATCH v3] cgroup: fix cgroup_rmdir() vs close(eventfd) race Li Zefan
[not found] ` <512208CE.8000003-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2013-02-18 17:17 ` Tejun Heo [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20130218171756.GE17414@htj.dyndns.org \
--to=tj-dgejt+ai2ygdnm+yrofe0a@public.gmane.org \
--cc=cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=kirill-oKw7cIdHH8eLwutG50LtGA@public.gmane.org \
--cc=linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox