From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id E1D626B01F4 for ; Wed, 28 Apr 2010 14:10:32 -0400 (EDT) Message-ID: <4BD879F7.1020102@redhat.com> Date: Wed, 28 Apr 2010 14:09:59 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [RFC PATCH] take all anon_vma locks in anon_vma_lock References: <1272403852-10479-1-git-send-email-mel@csn.ul.ie> <1272403852-10479-3-git-send-email-mel@csn.ul.ie> <20100427231007.GA510@random.random> <20100428091555.GB15815@csn.ul.ie> <20100428153525.GR510@random.random> <20100428155558.GI15815@csn.ul.ie> <20100428162305.GX510@random.random> <20100428134719.32e8011b@annuminas.surriel.com> <20100428180336.GC510@random.random> In-Reply-To: <20100428180336.GC510@random.random> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andrea Arcangeli Cc: Mel Gorman , Linux-MM , LKML , Minchan Kim , KAMEZAWA Hiroyuki , Christoph Lameter , Andrew Morton List-ID: On 04/28/2010 02:03 PM, Andrea Arcangeli wrote: > On Wed, Apr 28, 2010 at 01:47:19PM -0400, Rik van Riel wrote: >> static inline void anon_vma_unlock(struct vm_area_struct *vma) > > never mind as this is RFC, lock is clear enough > >> @@ -1762,7 +1760,8 @@ static int expand_downwards(struct vm_area_struct *vma, >> if (error) >> return error; >> >> - anon_vma_lock(vma); >> + spin_lock(&mm->page_table_lock); >> + anon_vma_lock(vma,&mm->page_table_lock); > > This will cause a lock inversion (page_table_lock can only be taken > after the anon_vma lock). I don't immediately see why the > page_table_lock here though? We need to safely walk the vma->anon_vma_chain / anon_vma_chain->same_vma list. So much for using the mmap_sem for read + the page_table_lock to lock the anon_vma_chain list. We'll need a new lock somewhere, probably in the mm_struct since one per process seems plenty. I'll add that in the next version of the patch. -- 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