Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755990AbZF1PEc (ORCPT ); Sun, 28 Jun 2009 11:04:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751785AbZF1PEY (ORCPT ); Sun, 28 Jun 2009 11:04:24 -0400 Received: from mga03.intel.com ([143.182.124.21]:52632 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751216AbZF1PEY (ORCPT ); Sun, 28 Jun 2009 11:04:24 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.42,303,1243839600"; d="scan'208";a="159336641" Date: Sun, 28 Jun 2009 23:04:08 +0800 From: Wu Fengguang To: KOSAKI Motohiro Cc: Minchan Kim , Johannes Weiner , David Howells , "riel@redhat.com" , Andrew Morton , LKML , Christoph Lameter , "peterz@infradead.org" , "tytso@mit.edu" , "linux-mm@kvack.org" , "elladan@eskimo.com" , "npiggin@suse.de" , "Barnes, Jesse" Subject: Re: Found the commit that causes the OOMs Message-ID: <20090628150407.GA25076@localhost> References: <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> <20090628113246.GA18409@localhost> <28c262360906280630n557bb182n5079e33d21ea4a83@mail.gmail.com> <2f11576a0906280749v25ab725dn8f98fbc1d2e5a5fd@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2f11576a0906280749v25ab725dn8f98fbc1d2e5a5fd@mail.gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1791 Lines: 42 On Sun, Jun 28, 2009 at 10:49:52PM +0800, KOSAKI Motohiro wrote: > >> In David's OOM case, there are two symptoms: > >> 1) 70000 unaccounted/leaked pages as found by Andrew > >>   (plus rather big number of PG_buddy and pagetable pages) > >> 2) almost zero active_file/inactive_file; small inactive_anon; > >>   many slab and active_anon pages. > >> > >> In the situation of (2), the slab cache is _under_ scanned. So David > >> got OOM when vmscan should have squeezed some free pages from the slab > >> cache. Which is one important side effect of MinChan's patch? > > > > My patch's side effect is (2). > > > > My guessing is following as. > > > > 1. The number of page scanned in shrink_slab is increased in shrink_page_list. > > And it is doubled for mapped page or swapcache. > > 2. shrink_page_list is called by shrink_inactive_list > > 3. shrink_inactive_list is called by shrink_list > > > > Look at the shrink_list. > > If inactive lru list is low, it always call shrink_active_list not > > shrink_inactive_list in case of anon. > > It means it doesn't increased sc->nr_scanned. > > Then shrink_slab can't shrink enough slab pages. > > So, David OOM have a lot of slab pages and active anon pages. > > > > Does it make sense ? > > If it make sense, we have to change shrink_slab's pressure method. > > What do you think ? > > I'm confused. > > if system have no swap, get_scan_ratio() always return anon=0%. > Then, the numver of inactive_anon is not effect to sc.nr_scanned. You are right. Hehe, so that's not a real side effect. -- 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/