From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933610Ab1JaRyd (ORCPT ); Mon, 31 Oct 2011 13:54:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56582 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755025Ab1JaRyc (ORCPT ); Mon, 31 Oct 2011 13:54:32 -0400 Date: Mon, 31 Oct 2011 17:34:22 +0100 From: Andrea Arcangeli To: Nai Xia Cc: Mel Gorman , Hugh Dickins , Pawel Sikora , Andrew Morton , linux-mm@kvack.org, jpiszcz@lucidpixels.com, arekm@pld-linux.org, linux-kernel@vger.kernel.org Subject: Re: kernel 3.0: BUG: soft lockup: find_get_pages+0x51/0x110 Message-ID: <20111031163422.GC3466@redhat.com> References: <201110122012.33767.pluto@agmk.net> <20111021155632.GD4082@suse.de> <20111021174120.GJ608@redhat.com> <201110221307.11615.nai.xia@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201110221307.11615.nai.xia@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Nai, On Sat, Oct 22, 2011 at 01:07:11PM +0800, Nai Xia wrote: > Yeah, anon_vma root lock is a big lock. And JFYI, actually I am doing > some very nasty hacking on anon_vma and one of the side effects is > breaking the root lock into pieces. But this area is pretty > convolved by many racing conditions. I hope some day I will finally make > my patch work and have your precious review of it. :-) :) It's going to be not trivial, initially it was not a shared lock but it wasn't safe that way (especially with migrate required a reliable rmap_walk) and using a shared lock across all same_anon_vma/same_vma lists was the only way to be safe and solve the races.