From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx143.postini.com [74.125.245.143]) by kanga.kvack.org (Postfix) with SMTP id 701816B0087 for ; Mon, 10 Dec 2012 23:40:46 -0500 (EST) Date: Tue, 11 Dec 2012 13:40:44 +0900 From: Minchan Kim Subject: Re: [RFC v2] Support volatile range for anon vma Message-ID: <20121211044044.GC22698@blaptop> References: <1351560594-18366-1-git-send-email-minchan@kernel.org> <50AD739A.30804@linaro.org> <50B6E1F9.5010301@linaro.org> <20121204000042.GB20395@bbox> <50BD4A70.9060506@linaro.org> <20121204072207.GA9782@blaptop> <50BE4B64.6000003@linaro.org> <20121205041855.GB9782@blaptop> <50C28EB4.6030505@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <50C28EB4.6030505@linaro.org> Sender: owner-linux-mm@kvack.org List-ID: To: John Stultz Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Lameter , Android Kernel Team , Robert Love , Mel Gorman , Hugh Dickins , Dave Hansen , Rik van Riel , Dave Chinner , Neil Brown , Mike Hommey , Taras Glek , KOSAKI Motohiro , KAMEZAWA Hiroyuki On Fri, Dec 07, 2012 at 04:49:56PM -0800, John Stultz wrote: > On 12/04/2012 08:18 PM, Minchan Kim wrote: > >On Tue, Dec 04, 2012 at 11:13:40AM -0800, John Stultz wrote: > >>I don't think the problem is when vmas being marked VM_VOLATILE are > >>being merged, its that when we mark the vma as *non-volatile*, and > >>remove the VM_VOLATILE flag we merge the non-volatile vmas with > >>neighboring vmas. So preserving the purged flag during that merge is > >>important. Again, the example I used to trigger this was an > >>alternating pattern of volatile and non volatile vmas, then marking > >>the entire range non-volatile (though sometimes in two overlapping > >>passes). > >Understood. Thanks. > >Below patch solves your problems? It's simple than yours. > > Yea, this is nicer then my fix. > Although I still need the purged handling in the vma merge code for > me to see the behavior I expect in my tests. > > I've integrated your patch and repushed my queue here: > http://git.linaro.org/gitweb?p=people/jstultz/android-dev.git;a=shortlog;h=refs/heads/dev/minchan-anonvol > > git://git.linaro.org/people/jstultz/android-dev.git dev/minchan-anonvol > > >Anyway, both yours and mine are not right fix. > >As I mentioned, locking scheme is broken. > >We need anon_vma_lock to handle purged and we should consider fork > >case, too. > Hrm. I'm sure you're right, as I've not yet fully grasped all the > locking rules here. Could you clarify how it is broken? And why is > the anon_vma_lock needed to manage the purged state that is part of > the vma itself? If you don't hold anon->lock, merge/split/fork can race with try_to_unmap so vma->[purged|vm_flags] would lose consistency. > > thanks > -john > > -- > 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 -- Kind regards, Minchan Kim -- 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