From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 1B51C6B0047 for ; Mon, 20 Sep 2010 04:02:05 -0400 (EDT) Date: Mon, 20 Sep 2010 04:01:36 -0400 (EDT) From: CAI Qian Message-ID: <1862979732.1343311284969696401.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com> In-Reply-To: <20100918152120.GA21343@barrios-desktop> Subject: Re: cgroup oom regression introduced by 6a5ce1b94e1e5979f8db579f77d6e08a5f44c13b MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: linux-mm , KOSAKI Motohiro , "M. Vefa Bicakci" , Johannes Weiner , Rik van Riel , stable@kernel.org, akpm@linux-foundation.org List-ID: ----- "Minchan Kim" wrote: > On Sat, Sep 18, 2010 at 08:52:34AM -0400, caiqian@redhat.com wrote: > > This test hung the kernel without triggering oom. > > # mount -t cgroup -o memory none /cgroup/memory/ > > # mkdir /cgroup/memory/A > > # echo $$ >/cgroup/memory/A/tasks > > # echo 4096M >/cgroup/memory/A/memory.limit_in_bytes > > # echo 4096M >/cgroup/memory/A/memory.memsw.limit_in_bytes > > # use malloc to allocate more than 4G memory. > > > > Sometimes, this had been thrown out of console, > > localhost.localdomain login: INFO: task sm1:5065 blocked for more > than 120 seconds. > > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this > message. > > sm1 D 00000000fffca130 0 5065 5051 0x00000080 > > ffff880c5f419c38 0000000000000086 ffff880c5f419bc8 > ffffffff81034ca8 > > ffff880100000000 0000000000015440 ffff880c608ab4e0 > 0000000000015440 > > ffff880c608aba40 ffff880c5f419fd8 ffff880c608aba48 > ffff880c5f419fd8 > > Call Trace: > > [] ? pvclock_clocksource_read+0x58/0xd0 > > [] ? sync_page+0x0/0x50 > > [] io_schedule+0x73/0xc0 > > [] sync_page+0x3d/0x50 > > [] __wait_on_bit_lock+0x5a/0xc0 > > [] __lock_page+0x67/0x70 > > [] ? wake_bit_function+0x0/0x50 > > [] ? find_get_page+0x1e/0xa0 > > [] filemap_fault+0x33c/0x450 > > [] __do_fault+0x54/0x550 > > [] ? __mem_cgroup_commit_charge+0x5a/0xa0 > > [] handle_mm_fault+0x1c2/0xc70 > > [] do_page_fault+0x11c/0x320 > > [] page_fault+0x25/0x30 > > > > Reverted the following commit from mmotm tree made the problem go > away. > > commit 6a5ce1b94e1e5979f8db579f77d6e08a5f44c13b > > Author: Minchan Kim > > Date: Thu Sep 16 01:17:26 2010 +0200 > > > > 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 > bisected > > the regression to > > > > 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 freozen, 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. > > > > Signed-off-by: KOSAKI Motohiro > > Signed-off-by: Minchan Kim > > Reported-by: M. Vefa Bicakci > > Acked-by: Rafael J. Wysocki > > Reviewed-by: Johannes Weiner > > Cc: Rik van Riel > > Cc: > > Signed-off-by: Andrew Morton > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index 225a759..f56a8c3 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -1804,12 +1804,11 @@ 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) { > > @@ -1827,8 +1826,36 @@ static bool shrink_zones(int priority, struct > zonelist *zonelist, > > } > > > > shrink_zone(priority, zone, sc); > > - all_unreclaimable = false; > > } > > +} > > + > > +static inline bool zone_reclaimable(struct zone *zone) > > +{ > > + return zone->pages_scanned < zone_reclaimable_pages(zone) * 6; > > +} > > + > > +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_reclaimable(zone)) { > > + all_unreclaimable = false; > > + break; > > + } > > + } > > + > > return all_unreclaimable; > > } > > > > @@ -1852,7 +1879,6 @@ static unsigned long > do_try_to_free_pages(struct zonelist *zonelist, > > struct scan_control *sc) > > { > > int priority; > > - bool all_unreclaimable; > > unsigned long total_scanned = 0; > > struct reclaim_state *reclaim_state = current->reclaim_state; > > struct zoneref *z; > > @@ -1869,7 +1895,7 @@ static unsigned long > do_try_to_free_pages(struct zonelist *zonelist, > > sc->nr_scanned = 0; > > if (!priority) > > disable_swap_token(); > > - all_unreclaimable = shrink_zones(priority, zonelist, sc); > > + shrink_zones(priority, zonelist, sc); > > /* > > * Don't shrink slabs when reclaiming memory from > > * over limit cgroups > > @@ -1931,7 +1957,7 @@ out: > > return sc->nr_reclaimed; > > > > /* top priority shrink_zones still had more to do? don't OOM, then > */ > > - if (scanning_global_lru(sc) && !all_unreclaimable) > > + if (!all_unreclaimable(zonelist, sc)) > > return 1; > > > > return 0; > > @@ -2197,8 +2223,7 @@ loop_again: > > total_scanned += sc.nr_scanned; > > if (zone->all_unreclaimable) > > continue; > > - if (nr_slab == 0 && > > - zone->pages_scanned >= (zone_reclaimable_pages(zone) * 6)) > > + if (nr_slab == 0 && !zone_reclaimable(zone)) > > zone->all_unreclaimable = 1; > > /* > > * If we've done a decent amount of scanning and > > Thanks for the reporting. > Could you test below patch? The problem went away after applied this patch. > > From 666a10163dcc2366a3cce64140487e5956f7f659 Mon Sep 17 00:00:00 > 2001 > From: Minchan Kim > Date: Sat, 18 Sep 2010 23:16:14 +0900 > Subject: [PATCH] Fix all_unreclaimable in memcg. > > vmscan-check-all_unreclaimable-in-direct-reclaim-path.patch > has a problem. It changed old behavior of memcg. > > When memory pressure in memcg is high, do_try_to_free_pages returns > 0. It causes mem_cgroup_out_of_memory so that any process in mem > group > would be killed. > But vmscan-check-all_unreclaimable-in-direct-reclaim-path.patch > changed > the old behavior. It returns 1 unconditionally regardless of > considering > global reclaim or memcg relcaim. It causes hang without triggering OOM > > in case of memcg direct reclaim. > > This patch fixes it. > > It's reported by caiqian@redhat.com. > (Thanks. Totally, it's my fault.) > > Reported-by: caiqian@redhat.com > Cc: KOSAKI Motohiro > Cc: Johannes Weiner > Cc: Rik van Riel > Cc: KAMEZAWA Hiroyuki > Cc: Balbir Singh > Signed-off-by: Minchan Kim > --- > mm/vmscan.c | 5 +---- > 1 files changed, 1 insertions(+), 4 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index ecae0ef..0119d0d 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1919,9 +1919,6 @@ static bool all_unreclaimable(struct zonelist > *zonelist, > 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)) > @@ -2035,7 +2032,7 @@ out: > return sc->nr_reclaimed; > > /* top priority shrink_zones still had more to do? don't OOM, then > */ > - if (!all_unreclaimable(zonelist, sc)) > + if (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc)) > return 1; > > return 0; > -- > 1.7.0.5 > > > -- > Kind regards, > Minchan Kim > > -- > 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 -- 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