On Sat, Sep 18, 2010 at 08:52:34AM -0400, caiqian@xxxxxxxxxx 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: > [<ffffffff81034ca8>] ? pvclock_clocksource_read+0x58/0xd0 > [<ffffffff810f2c60>] ? sync_page+0x0/0x50 > [<ffffffff81492553>] io_schedule+0x73/0xc0 > [<ffffffff810f2c9d>] sync_page+0x3d/0x50 > [<ffffffff81492cba>] __wait_on_bit_lock+0x5a/0xc0 > [<ffffffff810f2c37>] __lock_page+0x67/0x70 > [<ffffffff8107cf90>] ? wake_bit_function+0x0/0x50 > [<ffffffff810f2a6e>] ? find_get_page+0x1e/0xa0 > [<ffffffff810f4a5c>] filemap_fault+0x33c/0x450 > [<ffffffff81110524>] __do_fault+0x54/0x550 > [<ffffffff8113f30a>] ? __mem_cgroup_commit_charge+0x5a/0xa0 > [<ffffffff811132a2>] handle_mm_fault+0x1c2/0xc70 > [<ffffffff8149809c>] do_page_fault+0x11c/0x320 > [<ffffffff81494cd5>] page_fault+0x25/0x30 > > Reverted the following commit from mmotm tree made the problem go away. > commit 6a5ce1b94e1e5979f8db579f77d6e08a5f44c13b > Author: Minchan Kim <minchan.kim@xxxxxxxxx> > 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 <kosaki.motohiro@xxxxxxxxxxxxxx> > 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 <kosaki.motohiro@xxxxxxxxxxxxxx> > Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx> > Reported-by: M. Vefa Bicakci <bicave@xxxxxxxxxxxxxxx> > Acked-by: Rafael J. Wysocki <rjw@xxxxxxx> > Reviewed-by: Johannes Weiner <hannes@xxxxxxxxxxx> > Cc: Rik van Riel <riel@xxxxxxxxxx> > Cc: <stable@xxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > 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? >From 666a10163dcc2366a3cce64140487e5956f7f659 Mon Sep 17 00:00:00 2001 From: Minchan Kim <minchan.kim@xxxxxxxxx> 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@xxxxxxxxxxx (Thanks. Totally, it's my fault.) Reported-by: caiqian@xxxxxxxxxx Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Cc: Balbir Singh <balbir@xxxxxxxxxx> Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx> --- 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@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . 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