From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 138996B0047 for ; Wed, 8 Sep 2010 11:45:40 -0400 (EDT) Received: by gyf3 with SMTP id 3so117701gyf.14 for ; Wed, 08 Sep 2010 08:45:38 -0700 (PDT) Date: Thu, 9 Sep 2010 00:45:27 +0900 From: Minchan Kim Subject: Re: [PATCH] vmscan: check all_unreclaimable in direct reclaim path Message-ID: <20100908154527.GA5936@barrios-desktop> References: <1283697637-3117-1-git-send-email-minchan.kim@gmail.com> <20100908054831.GB20955@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100908054831.GB20955@cmpxchg.org> Sender: owner-linux-mm@kvack.org To: Andrew Morton , Johannes Weiner Cc: linux-mm , LKML , KOSAKI Motohiro , Rik van Riel , "Rafael J. Wysocki" , "M. Vefa Bicakci" , stable@kernel.org List-ID: On Wed, Sep 08, 2010 at 07:48:31AM +0200, Johannes Weiner wrote: > On Sun, Sep 05, 2010 at 11:40:37PM +0900, Minchan Kim wrote: > > M. Vefa Bicakci reported 2.6.35 kernel hang up when hibernation on his > > 32bit 3GB mem machine. (https://bugzilla.kernel.org/show_bug.cgi?id=16771) > > Also he was bisected first bad commit is below > > > > commit bb21c7ce18eff8e6e7877ca1d06c6db719376e3c > > Author: KOSAKI Motohiro > > Date: Fri Jun 4 14:15:05 2010 -0700 > > > > vmscan: fix do_try_to_free_pages() return value when priority==0 reclaim failure > > > > At first impression, this seemed very strange because the above commit only > > chenged function return value and hibernate_preallocate_memory() ignore > > return value of shrink_all_memory(). But it's related. > > > > Now, page allocation from hibernation code may enter infinite loop if > > the system has highmem. The reasons are that vmscan don't care enough > > OOM case when oom_killer_disabled. > > > > The problem sequence is following as. > > > > 1. hibernation > > 2. oom_disable > > 3. alloc_pages > > 4. do_try_to_free_pages > > if (scanning_global_lru(sc) && !all_unreclaimable) > > return 1; > > > > If kswapd is not freezed, it would set zone->all_unreclaimable to 1 and then > > shrink_zones maybe return true(ie, all_unreclaimable is true). > > so at last, alloc_pages could go to _nopage_. If it is, it should have no problem. > > > > This patch adds all_unreclaimable check to protect in direct reclaim path, too. > > It can care of hibernation OOM case and help bailout all_unreclaimable case slightly. > > > > Cc: Johannes Weiner > > Cc: Rik van Riel > > Cc: "Rafael J. Wysocki" > > Cc: M. Vefa Bicakci > > Cc: stable@kernel.org > > Signed-off-by: KOSAKI Motohiro > > Signed-off-by: Minchan Kim > > --- > > mm/vmscan.c | 33 +++++++++++++++++++++++++++------ > > 1 files changed, 27 insertions(+), 6 deletions(-) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index f620ab3..53b23a7 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -1893,12 +1893,11 @@ static void shrink_zone(int priority, struct zone *zone, > > * If a zone is deemed to be full of pinned pages then just give it a light > > * scan then give up on it. > > */ > > -static bool shrink_zones(int priority, struct zonelist *zonelist, > > +static void shrink_zones(int priority, struct zonelist *zonelist, > > struct scan_control *sc) > > { > > struct zoneref *z; > > struct zone *zone; > > - bool all_unreclaimable = true; > > > > for_each_zone_zonelist_nodemask(zone, z, zonelist, > > gfp_zone(sc->gfp_mask), sc->nodemask) { > > @@ -1916,8 +1915,31 @@ static bool shrink_zones(int priority, struct zonelist *zonelist, > > } > > > > shrink_zone(priority, zone, sc); > > - all_unreclaimable = false; > > } > > +} > > + > > +static inline bool all_unreclaimable(struct zonelist *zonelist, > > + struct scan_control *sc) > > +{ > > + struct zoneref *z; > > + struct zone *zone; > > + bool all_unreclaimable = true; > > + > > + if (!scanning_global_lru(sc)) > > + return false; > > + > > + for_each_zone_zonelist_nodemask(zone, z, zonelist, > > + gfp_zone(sc->gfp_mask), sc->nodemask) { > > + if (!populated_zone(zone)) > > + continue; > > + if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) > > + continue; > > + if (zone->pages_scanned < (zone_reclaimable_pages(zone) * 6)) { > > Small nitpick: kswapd does the same check against the magic number, > could you move it into a separate function? zone_reclaimable()? Nice cleanup. Thanks, Hannes. > > Otherwise, > Reviewed-by: Johannes Weiner > == CUT HERE == Changelog v2 * cleanup zone_reclaimable(suggested by Johannes) * rebase on mmotm-08-27