From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754017Ab2KZP6Q (ORCPT ); Mon, 26 Nov 2012 10:58:16 -0500 Received: from mail-ie0-f174.google.com ([209.85.223.174]:57499 "EHLO mail-ie0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753122Ab2KZP6P (ORCPT ); Mon, 26 Nov 2012 10:58:15 -0500 MIME-Version: 1.0 In-Reply-To: <20121122151028.GA1834@t510.redhat.com> References: <6602296b38c073a5c6faa13ddbc74ceb1eceb2dd.1352656285.git.aquini@redhat.com> <50A7D0FA.2080709@gmail.com> <20121117215434.GA23879@x61.redhat.com> <20121120141438.GA21672@x61.redhat.com> <50AC2BCC.6050507@gmail.com> <20121122000114.GB1815@t510.redhat.com> <50AE3463.1040107@gmail.com> <20121122151028.GA1834@t510.redhat.com> From: Sasha Levin Date: Mon, 26 Nov 2012 10:57:54 -0500 Message-ID: Subject: Re: [PATCH v12 4/7] mm: introduce compaction and migration for ballooned pages To: Rafael Aquini Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Andrew Morton , Mel Gorman , "Michael S. Tsirkin" , Minchan Kim , Rik van Riel , Rusty Russell Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 22, 2012 at 10:10 AM, Rafael Aquini wrote: > On Thu, Nov 22, 2012 at 09:19:15AM -0500, Sasha Levin wrote: >> And managed to reproduce it only once through last night, here is the dump I got >> before the oops: >> >> [ 2760.356820] page:ffffea0000d00e00 count:1 mapcount:-2147287036 mapping:00000000000004f4 index:0xd00e00000003 >> [ 2760.362354] page flags: 0x350000000001800(private|private_2) >> > > Thanks alot for following up this one Sasha. > > > We're stumbling across a private page -- seems something in your setup is doing > this particular usage, and that's probably why I'm not seeing the same here. > > Regardless being a particular case or not, we shouldn't be poking at that > private page, so I figured the tests I'm doing at balloon_page_movable() are > incomplete and dumb. > > Perhaps, a better way to proceed here would be assuring the NR_PAGEFLAGS > rightmost bits from page->flags are all cleared, as this is the state a page > coming from buddy to the balloon list will be, and this is the state the balloon > page flags will be kept as long as it lives as such (we don't play with any flag > at balloon level). > > > Here goes what I'll propose after you confirm it doesn't trigger your crash > anymore, as it simplifies the code and reduces the testing battery @ > balloon_page_movable() -- ballooned pages have no flags set, 1 refcount and 0 > mapcount, always. > > > Could you give this a try? > > Thank you! Ran it for a while, no more BUGs, yay :) Thanks, Sasha From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx198.postini.com [74.125.245.198]) by kanga.kvack.org (Postfix) with SMTP id 9FD746B0062 for ; Mon, 26 Nov 2012 10:58:15 -0500 (EST) Received: by mail-ie0-f169.google.com with SMTP id c14so3682885ieb.14 for ; Mon, 26 Nov 2012 07:58:15 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20121122151028.GA1834@t510.redhat.com> References: <6602296b38c073a5c6faa13ddbc74ceb1eceb2dd.1352656285.git.aquini@redhat.com> <50A7D0FA.2080709@gmail.com> <20121117215434.GA23879@x61.redhat.com> <20121120141438.GA21672@x61.redhat.com> <50AC2BCC.6050507@gmail.com> <20121122000114.GB1815@t510.redhat.com> <50AE3463.1040107@gmail.com> <20121122151028.GA1834@t510.redhat.com> From: Sasha Levin Date: Mon, 26 Nov 2012 10:57:54 -0500 Message-ID: Subject: Re: [PATCH v12 4/7] mm: introduce compaction and migration for ballooned pages Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Rafael Aquini Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Andrew Morton , Mel Gorman , "Michael S. Tsirkin" , Minchan Kim , Rik van Riel , Rusty Russell On Thu, Nov 22, 2012 at 10:10 AM, Rafael Aquini wrote: > On Thu, Nov 22, 2012 at 09:19:15AM -0500, Sasha Levin wrote: >> And managed to reproduce it only once through last night, here is the dump I got >> before the oops: >> >> [ 2760.356820] page:ffffea0000d00e00 count:1 mapcount:-2147287036 mapping:00000000000004f4 index:0xd00e00000003 >> [ 2760.362354] page flags: 0x350000000001800(private|private_2) >> > > Thanks alot for following up this one Sasha. > > > We're stumbling across a private page -- seems something in your setup is doing > this particular usage, and that's probably why I'm not seeing the same here. > > Regardless being a particular case or not, we shouldn't be poking at that > private page, so I figured the tests I'm doing at balloon_page_movable() are > incomplete and dumb. > > Perhaps, a better way to proceed here would be assuring the NR_PAGEFLAGS > rightmost bits from page->flags are all cleared, as this is the state a page > coming from buddy to the balloon list will be, and this is the state the balloon > page flags will be kept as long as it lives as such (we don't play with any flag > at balloon level). > > > Here goes what I'll propose after you confirm it doesn't trigger your crash > anymore, as it simplifies the code and reduces the testing battery @ > balloon_page_movable() -- ballooned pages have no flags set, 1 refcount and 0 > mapcount, always. > > > Could you give this a try? > > Thank you! Ran it for a while, no more BUGs, yay :) Thanks, Sasha -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: Re: [PATCH v12 4/7] mm: introduce compaction and migration for ballooned pages Date: Mon, 26 Nov 2012 10:57:54 -0500 Message-ID: References: <6602296b38c073a5c6faa13ddbc74ceb1eceb2dd.1352656285.git.aquini@redhat.com> <50A7D0FA.2080709@gmail.com> <20121117215434.GA23879@x61.redhat.com> <20121120141438.GA21672@x61.redhat.com> <50AC2BCC.6050507@gmail.com> <20121122000114.GB1815@t510.redhat.com> <50AE3463.1040107@gmail.com> <20121122151028.GA1834@t510.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20121122151028.GA1834@t510.redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Rafael Aquini Cc: Rik van Riel , "Michael S. Tsirkin" , Minchan Kim , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-mm@kvack.org, Andrew Morton List-Id: virtualization@lists.linuxfoundation.org On Thu, Nov 22, 2012 at 10:10 AM, Rafael Aquini wrote: > On Thu, Nov 22, 2012 at 09:19:15AM -0500, Sasha Levin wrote: >> And managed to reproduce it only once through last night, here is the dump I got >> before the oops: >> >> [ 2760.356820] page:ffffea0000d00e00 count:1 mapcount:-2147287036 mapping:00000000000004f4 index:0xd00e00000003 >> [ 2760.362354] page flags: 0x350000000001800(private|private_2) >> > > Thanks alot for following up this one Sasha. > > > We're stumbling across a private page -- seems something in your setup is doing > this particular usage, and that's probably why I'm not seeing the same here. > > Regardless being a particular case or not, we shouldn't be poking at that > private page, so I figured the tests I'm doing at balloon_page_movable() are > incomplete and dumb. > > Perhaps, a better way to proceed here would be assuring the NR_PAGEFLAGS > rightmost bits from page->flags are all cleared, as this is the state a page > coming from buddy to the balloon list will be, and this is the state the balloon > page flags will be kept as long as it lives as such (we don't play with any flag > at balloon level). > > > Here goes what I'll propose after you confirm it doesn't trigger your crash > anymore, as it simplifies the code and reduces the testing battery @ > balloon_page_movable() -- ballooned pages have no flags set, 1 refcount and 0 > mapcount, always. > > > Could you give this a try? > > Thank you! Ran it for a while, no more BUGs, yay :) Thanks, Sasha