From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753155Ab0DOHAN (ORCPT ); Thu, 15 Apr 2010 03:00:13 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:53367 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752812Ab0DOHAK (ORCPT ); Thu, 15 Apr 2010 03:00:10 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Thu, 15 Apr 2010 15:56:11 +0900 From: KAMEZAWA Hiroyuki To: Daisuke Nishimura Cc: LKML , linux-mm , Mel Gorman , Rik van Riel , Minchan Kim , Balbir Singh , KOSAKI Motohiro , Christoph Lameter , Andrea Arcangeli , Andrew Morton Subject: Re: [RFC][BUGFIX][PATCH 1/2] memcg: fix charge bypass route of migration Message-Id: <20100415155611.da707913.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100415154324.834dace9.nishimura@mxp.nes.nec.co.jp> References: <20100413134207.f12cdc9c.nishimura@mxp.nes.nec.co.jp> <20100415120516.3891ce46.kamezawa.hiroyu@jp.fujitsu.com> <20100415154324.834dace9.nishimura@mxp.nes.nec.co.jp> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.0.2 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 15 Apr 2010 15:43:24 +0900 Daisuke Nishimura wrote: > On Thu, 15 Apr 2010 12:05:16 +0900, KAMEZAWA Hiroyuki wrote: > > I'd like to wait until next mmotm comes out. (So, [RFC]) I'll rebase > > This patch is based on > > mmotm-2010/04/05 > > + > > mm-migration-take-a-reference-to-the-anon_vma-before-migrating.patch > > mm-migration-do-not-try-to-migrate-unmapped-anonymous-pages.patch > > mm-share-the-anon_vma-ref-counts-between-ksm-and-page-migration.patch > > mm-migration-allow-the-migration-of-pageswapcache-pages.patch > > memcg-fix-prepare-migration.patch > > > > == > > From: KAMEZAWA Hiroyuki > > > > This is an additonal fix to memcg-fix-prepare-migration.patch > > > > Now, try_charge can bypass charge if TIF_MEMDIE at el are marked on the caller. > > In this case, the charge is bypassed. This makes accounts corrupted. > > (PageCgroup will be marked as PCG_USED even if bypassed, and css->refcnt > > can leak.) > > > > This patch clears passed "*memcg" in bypass route. > > > > Because usual page allocater passes memcg=NULL, this patch only affects > > some special case as > > - move account > > - migration > > - swapin. > > > > Signed-off-by: KAMEZAWA Hiroyuki > > --- > > mm/memcontrol.c | 7 +++++-- > > 1 file changed, 5 insertions(+), 2 deletions(-) > > > > Index: mmotm-temp/mm/memcontrol.c > > =================================================================== > > --- mmotm-temp.orig/mm/memcontrol.c > > +++ mmotm-temp/mm/memcontrol.c > > @@ -1606,8 +1606,12 @@ static int __mem_cgroup_try_charge(struc > > * MEMDIE process. > > */ > > if (unlikely(test_thread_flag(TIF_MEMDIE) > > - || fatal_signal_pending(current))) > > + || fatal_signal_pending(current))) { > > + /* Showing we skipped charge */ > > + if (memcg) > > + *memcg = NULL; > > goto bypass; > > + } > > > I'm sorry, I can't understand what this part fixes. > We set *memcg to NULL at "bypass" part already: > > 1740 bypass: > 1741 *memcg = NULL; > 1742 return 0; > > and __mem_cgroup_try_charge() is never called with @memcg == NULL, IIUC. > I totally missed that..Sigh. > > /* > > * We always charge the cgroup the mm_struct belongs to. > > @@ -2523,7 +2527,6 @@ int mem_cgroup_prepare_migration(struct > > ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, ptr, false); > > css_put(&mem->css); > > } > > - *ptr = mem; > > return ret; > > } > > > I sent a patch to Andrew to fix this part yesterday :) > Ok, ignore this patch. -Kame