From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 8CAFA62008B for ; Wed, 5 May 2010 12:13:50 -0400 (EDT) Date: Wed, 5 May 2010 18:13:19 +0200 From: Andrea Arcangeli Subject: Re: [PATCH 1/2] mm,migration: Prevent rmap_walk_[anon|ksm] seeing the wrong VMA information Message-ID: <20100505161319.GQ5835@random.random> References: <1273065281-13334-1-git-send-email-mel@csn.ul.ie> <1273065281-13334-2-git-send-email-mel@csn.ul.ie> <20100505145620.GP20979@csn.ul.ie> <20100505155454.GT20979@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100505155454.GT20979@csn.ul.ie> Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: Linus Torvalds , Andrew Morton , Linux-MM , LKML , Minchan Kim , KAMEZAWA Hiroyuki , Christoph Lameter , Rik van Riel List-ID: On Wed, May 05, 2010 at 04:54:54PM +0100, Mel Gorman wrote: > I'm still thinking of the ordering but one possibility would be to use a mutex I can't take mutex in split_huge_page... so I'd need to use an other solution. > Not yet. Rik's patch that takes the locks in the faster path is preferable to me, it's just simpler, you know the really "strong" long is the page->mapping/anon_vma->lock and nothing else. You've a page, you take that lock, you're done for that very page. Sure that means updating vm_start/vm_pgoff then requires locking all anon_vmas that the vma registered into, but that's conceptually simpler and it doesn't alter the page_lock_anon_vma semantics. Now I wonder if you said the same_anon_vma is in order, but the same_vma is not, if it's safe to lock the same_vma in list order in anon_vma_lock, I didn't experience problems on the anon_vma_chain branch but anon_vma_lock disables all lockdep lock inversion checking. -- 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