Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932749AbaLBAjs (ORCPT ); Mon, 1 Dec 2014 19:39:48 -0500 Received: from mail-lb0-f175.google.com ([209.85.217.175]:43112 "EHLO mail-lb0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754137AbaLBAjr (ORCPT ); Mon, 1 Dec 2014 19:39:47 -0500 MIME-Version: 1.0 In-Reply-To: <1417477480.21136.0@mail.thefacebook.com> References: <20141127225637.GA24019@redhat.com> <547b8a45.6e608c0a.20f9.1002@mx.google.com> <547bbe36.48548c0a.105c.779c@mx.google.com> <20141201191431.GA17385@linux.vnet.ibm.com> <547ccf74.a5198c0a.25de.26d9@mx.google.com> <20141201230339.GA20487@ret.masoncoding.com> <1417477480.21136.0@mail.thefacebook.com> Date: Mon, 1 Dec 2014 16:39:45 -0800 X-Google-Sender-Auth: KJ_qhHDKvWVwMNy7xVbfAHfH4So Message-ID: Subject: Re: frequent lockups in 3.18rc4 From: Linus Torvalds To: Chris Mason Cc: =?UTF-8?Q?D=C3=A2niel_Fraga?= , Dave Jones , Sasha Levin , "Paul E. McKenney" , Linux Kernel Mailing List 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 Mon, Dec 1, 2014 at 3:44 PM, Chris Mason wrote: > > But looking harder it's probably inside wait_sb_inodes: > > spin_lock(&inode_sb_list_lock); Yeah, that's a known pain-point for sync(), although nobody has really cared enough, since performance of parallel sync() calls is usually not very high on anybody's list of things to care about except when it occasionally shows up on some old Unix benchmark (maybe AIM, I forget). Anyway, lock debugging will make what is usually not noticeable into a "whee, that's horrible", because the lock debugging overhead is often many *many* times higher than the cost of the code inside the lock.. 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/