Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754283AbaLMXKD (ORCPT ); Sat, 13 Dec 2014 18:10:03 -0500 Received: from mail-qc0-f181.google.com ([209.85.216.181]:51105 "EHLO mail-qc0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750789AbaLMXKA (ORCPT ); Sat, 13 Dec 2014 18:10:00 -0500 MIME-Version: 1.0 In-Reply-To: References: <20141205171501.GA1320@redhat.com> <1417806247.4845.1@mail.thefacebook.com> <20141211145408.GB16800@redhat.com> <20141212185454.GB4716@redhat.com> <20141213165915.GA12756@redhat.com> <20141213223616.GA22559@redhat.com> Date: Sat, 13 Dec 2014 15:09:59 -0800 X-Google-Sender-Auth: IVWmPrmjkYbxbngQiQx0c5fZxwM Message-ID: Subject: Re: frequent lockups in 3.18rc4 From: Linus Torvalds To: Dave Jones , Linus Torvalds , Chris Mason , Mike Galbraith , Ingo Molnar , Peter Zijlstra , =?UTF-8?Q?D=C3=A2niel_Fraga?= , Sasha Levin , "Paul E. McKenney" , Linux Kernel Mailing List , Al Viro , Thomas Gleixner Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Dec 13, 2014 at 2:59 PM, Linus Torvalds wrote: > The generic code does that mnt_want_write/mnt_drop_write > dance adound the call to setxattr, and that in turn does > > while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) > cpu_relax(); > > with preemption explicitly disabled. Btw, I see no reason why mnt_want_write/mnt_drop_write disables preemption. They don't care, they just care about the ordering of the write counts and the MNT_WRITE_HOLD bit. It's the code that sets the bit that should care, afaik. But maybe I'm missing something. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/