From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id B3CC06B01F1 for ; Thu, 26 Aug 2010 09:32:17 -0400 (EDT) Message-ID: <4C766CD7.8000004@redhat.com> Date: Thu, 26 Aug 2010 09:32:07 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH] mm: fix hang on anon_vma->root->lock References: In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Hugh Dickins Cc: Linus Torvalds , Andrew Morton , Andrea Arcangeli , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On 08/26/2010 02:12 AM, Hugh Dickins wrote: > After several hours, kbuild tests hang with anon_vma_prepare() spinning on > a newly allocated anon_vma's lock - on a box with CONFIG_TREE_PREEMPT_RCU=y > (which makes this very much more likely, but it could happen without). > > The ever-subtle page_lock_anon_vma() now needs a further twist: since > anon_vma_prepare() and anon_vma_fork() are liable to change the ->root > of a reused anon_vma structure at any moment, page_lock_anon_vma() > needs to check page_mapped() again before succeeding, otherwise > page_unlock_anon_vma() might address a different root->lock. > > Signed-off-by: Hugh Dickins Reviewed-by: Rik van Riel And yes, AFAIK this code lived just in -mm up to now. -- All rights reversed -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org