Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757103AbZF1Qxi (ORCPT ); Sun, 28 Jun 2009 12:53:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752806AbZF1Qxa (ORCPT ); Sun, 28 Jun 2009 12:53:30 -0400 Received: from mail-yx0-f188.google.com ([209.85.210.188]:51322 "EHLO mail-yx0-f188.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752628AbZF1Qx3 convert rfc822-to-8bit (ORCPT ); Sun, 28 Jun 2009 12:53:29 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=OhC5UrCMsfe3fBL+8vUEZZS4CLYaFf/hp3+UtSCPit/dvGdLK1NRnQE45Gmp1VrMjE jkqqzATY9txEJ3TciofiFb1HubjoDC1p9plrIjfJN/W6qrfJbmmQ4s6oW+3QztuUketI obh/bk56BsE1Xoab/rZ3LsBprT5kLEKiUEabY= MIME-Version: 1.0 In-Reply-To: <20090627153630.GA6803@cmpxchg.org> References: <20090624023251.GA16483@localhost> <32411.1245336412@redhat.com> <20090517022327.280096109@intel.com> <2015.1245341938@redhat.com> <20090618095729.d2f27896.akpm@linux-foundation.org> <7561.1245768237@redhat.com> <26537.1246086769@redhat.com> <20090627125412.GA1667@cmpxchg.org> <28c262360906270650v6c276591u417d64573ecfba29@mail.gmail.com> <20090627153630.GA6803@cmpxchg.org> Date: Mon, 29 Jun 2009 01:53:32 +0900 Message-ID: <28c262360906280953r67a8f450s62931bd7fa8d6108@mail.gmail.com> Subject: Re: Found the commit that causes the OOMs From: Minchan Kim To: Johannes Weiner Cc: David Howells , Wu Fengguang , "riel@redhat.com" , Andrew Morton , LKML , Christoph Lameter , KOSAKI Motohiro , "peterz@infradead.org" , "tytso@mit.edu" , "linux-mm@kvack.org" , "elladan@eskimo.com" , "npiggin@suse.de" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3784 Lines: 87 On Sun, Jun 28, 2009 at 12:36 AM, Johannes Weiner wrote: > On Sat, Jun 27, 2009 at 10:50:25PM +0900, Minchan Kim wrote: >> Hi, Hannes. >> >> On Sat, Jun 27, 2009 at 9:54 PM, Johannes Weiner wrote: >> > On Sat, Jun 27, 2009 at 08:12:49AM +0100, David Howells wrote: >> >> >> >> I've managed to bisect things to find the commit that causes the OOMs.  It's: >> >> >> >>       commit 69c854817566db82c362797b4a6521d0b00fe1d8 >> >>       Author: MinChan Kim >> >>       Date:   Tue Jun 16 15:32:44 2009 -0700 >> >> >> >>           vmscan: prevent shrinking of active anon lru list in case of no swap space V3 >> >> >> >>           shrink_zone() can deactivate active anon pages even if we don't have a >> >>           swap device.  Many embedded products don't have a swap device.  So the >> >>           deactivation of anon pages is unnecessary. >> >> >> >>           This patch prevents unnecessary deactivation of anon lru pages.  But, it >> >>           don't prevent aging of anon pages to swap out. >> >> >> >>           Signed-off-by: Minchan Kim >> >>           Acked-by: KOSAKI Motohiro >> >>           Cc: Johannes Weiner >> >>           Acked-by: Rik van Riel >> >>           Signed-off-by: Andrew Morton >> >>           Signed-off-by: Linus Torvalds >> >> >> >> This exhibits the problem.  The previous commit: >> >> >> >>       commit 35282a2de4e5e4e173ab61aa9d7015886021a821 >> >>       Author: Brice Goglin >> >>       Date:   Tue Jun 16 15:32:43 2009 -0700 >> >> >> >>           migration: only migrate_prep() once per move_pages() >> >> >> >> survives 16 iterations of the LTP syscall testsuite without exhibiting the >> >> problem. >> > >> > Here is the patch in question: >> > >> > diff --git a/mm/vmscan.c b/mm/vmscan.c >> > index 7592d8e..879d034 100644 >> > --- a/mm/vmscan.c >> > +++ b/mm/vmscan.c >> > @@ -1570,7 +1570,7 @@ static void shrink_zone(int priority, struct zone *zone, >> >         * Even if we did not try to evict anon pages at all, we want to >> >         * rebalance the anon lru active/inactive ratio. >> >         */ >> > -       if (inactive_anon_is_low(zone, sc)) >> > +       if (inactive_anon_is_low(zone, sc) && nr_swap_pages > 0) >> >                shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); >> > >> >        throttle_vm_writeout(sc->gfp_mask); >> > >> > When this was discussed, I think we missed that nr_swap_pages can >> > actually get zero on swap systems as well and this should have been >> > total_swap_pages - otherwise we also stop balancing the two anon lists >> > when swap is _full_ which was not the intention of this change at all. >> >> At that time we considered it so that we didn't prevent anon list >> aging for background reclaim. >> Do you think it is not enough ? > > With a heavy multiprocess anon load, direct reclaimers will likely > reuse the reclaimed pages for anon mappings, so you have a handful of > processes shuffling pages on the active list and only one thread that > tries to balance.  I can imagine that it can not keep up for long. I agree. :) total_swap_pages is better than nr_swap_pages although it isn't related this problem. > -- Kinds regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/