From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: Racy manipulation of task_struct->flags in cgroups code causes hard to reproduce kernel panics Date: Sat, 20 Sep 2014 16:30:12 +0200 Message-ID: <20140920143012.GL2832@worktop.localdomain> References: <201409192053.IHJ35462.JLOMOSOFFVtQFH@I-love.SAKURA.ne.jp> <541D16EA.70407@huawei.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <541D16EA.70407-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Zefan Li Cc: Tetsuo Handa , mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, fernando_b1-Zyj7fXuS5i5L9jVzuh4AOg@public.gmane.org, keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org On Sat, Sep 20, 2014 at 01:55:54PM +0800, Zefan Li wrote: > We should make the updating of this flag atomic. > /* Per-process atomic flags. */ > #define PFA_NO_NEW_PRIVS 0x00000001 /* May not gain new privileges. */ > +#define PFA_SPREAD_PAGE 0x00000002 /* Spread page cache over cpuset */ > +#define PFA_SPREAD_SLAB 0x00000004 /* Spread some slab caches over cpuset */ Ooh, I was not ware we had those.. /me checks where that came from. Hmm weird, while I did get that patch it had a seccomp prefix when landing in my inbox so I ignored it. However the commit has a sched prefix (which I would not have ignored). Dubious things happened here. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757493AbaITOaZ (ORCPT ); Sat, 20 Sep 2014 10:30:25 -0400 Received: from casper.infradead.org ([85.118.1.10]:46234 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754921AbaITOaX (ORCPT ); Sat, 20 Sep 2014 10:30:23 -0400 Date: Sat, 20 Sep 2014 16:30:12 +0200 From: Peter Zijlstra To: Zefan Li Cc: Tetsuo Handa , mingo@redhat.com, tj@kernel.org, akpm@linux-foundation.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, fernando_b1@lab.ntt.co.jp, keescook@chromium.org Subject: Re: Racy manipulation of task_struct->flags in cgroups code causes hard to reproduce kernel panics Message-ID: <20140920143012.GL2832@worktop.localdomain> References: <201409192053.IHJ35462.JLOMOSOFFVtQFH@I-love.SAKURA.ne.jp> <541D16EA.70407@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <541D16EA.70407@huawei.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 20, 2014 at 01:55:54PM +0800, Zefan Li wrote: > We should make the updating of this flag atomic. > /* Per-process atomic flags. */ > #define PFA_NO_NEW_PRIVS 0x00000001 /* May not gain new privileges. */ > +#define PFA_SPREAD_PAGE 0x00000002 /* Spread page cache over cpuset */ > +#define PFA_SPREAD_SLAB 0x00000004 /* Spread some slab caches over cpuset */ Ooh, I was not ware we had those.. /me checks where that came from. Hmm weird, while I did get that patch it had a seccomp prefix when landing in my inbox so I ignored it. However the commit has a sched prefix (which I would not have ignored). Dubious things happened here.