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Date: Tue, 09 Jul 2013 15:19:21 +0200 From: "azurIt" <azurit@...ox.sk> To: Michal Hocko <mhocko@...e.cz> Cc: Johannes Weiner <hannes@...xchg.org>, <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>, cgroups mailinglist <cgroups@...r.kernel.org>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> Subject: Re: [PATCH for 3.2] memcg: do not trap chargers with full callstack on OOM >On Mon 08-07-13 01:42:24, azurIt wrote: >> > CC: "Michal Hocko" <mhocko@...e.cz>, linux-kernel@...r.kernel.org, linux-mm@...ck.org, "cgroups mailinglist" <cgroups@...r.kernel.org>, "KAMEZAWA Hiroyuki" <kamezawa.hiroyu@...fujitsu.com> >> >On Fri, Jul 05, 2013 at 09:02:46PM +0200, azurIt wrote: >> >> >I looked at your debug messages but could not find anything that would >> >> >hint at a deadlock. All tasks are stuck in the refrigerator, so I >> >> >assume you use the freezer cgroup and enabled it somehow? >> >> >> >> >> >> Yes, i'm really using freezer cgroup BUT i was checking if it's not >> >> doing problems - unfortunately, several days passed from that day >> >> and now i don't fully remember if i was checking it for both cases >> >> (unremoveabled cgroups and these freezed processes holding web >> >> server port). I'm 100% sure i was checking it for unremoveable >> >> cgroups but not so sure for the other problem (i had to act quickly >> >> in that case). Are you sure (from stacks) that freezer cgroup was >> >> enabled there? >> > >> >Yeah, all the traces without exception look like this: >> > >> >1372089762/23433/stack:[<ffffffff81080925>] refrigerator+0x95/0x160 >> >1372089762/23433/stack:[<ffffffff8106ab7b>] get_signal_to_deliver+0x1cb/0x540 >> >1372089762/23433/stack:[<ffffffff8100188b>] do_signal+0x6b/0x750 >> >1372089762/23433/stack:[<ffffffff81001fc5>] do_notify_resume+0x55/0x80 >> >1372089762/23433/stack:[<ffffffff815cac77>] int_signal+0x12/0x17 >> >1372089762/23433/stack:[<ffffffffffffffff>] 0xffffffffffffffff >> > >> >so the freezer was already enabled when you took the backtraces. >> > >> >> Btw, what about that other stacks? I mean this file: >> >> http://watchdog.sk/lkml/memcg-bug-7.tar.gz >> >> >> >> It was taken while running the kernel with your patch and from >> >> cgroup which was under unresolveable OOM (just like my very original >> >> problem). >> > >> >I looked at these traces too, but none of the tasks are stuck in rmdir >> >or the OOM path. Some /are/ in the page fault path, but they are >> >happily doing reclaim and don't appear to be stuck. So I'm having a >> >hard time matching this data to what you otherwise observed. > >Agreed. > >> >However, based on what you reported the most likely explanation for >> >the continued hangs is the unfinished OOM handling for which I sent >> >the followup patch for arch/x86/mm/fault.c. >> >> Johannes, >> >> today I tested both of your patches but problem with unremovable >> cgroups, unfortunately, persists. > >Is the group empty again with marked under_oom? Now i realized that i forgot to remove UID from that cgroup before trying to remove it, so cgroup cannot be removed anyway (we are using third party cgroup called cgroup-uid from Andrea Righi, which is able to associate all user's processes with target cgroup). Look here for cgroup-uid patch: https://www.develer.com/~arighi/linux/patches/cgroup-uid/cgroup-uid-v8.patch ANYWAY, i'm 101% sure that 'tasks' file was empty and 'under_oom' was permanently '1'. azur -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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