Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751105Ab3IJSiA (ORCPT ); Tue, 10 Sep 2013 14:38:00 -0400 Received: from zene.cmpxchg.org ([85.214.230.12]:54719 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751022Ab3IJShy (ORCPT ); Tue, 10 Sep 2013 14:37:54 -0400 Date: Tue, 10 Sep 2013 14:37:40 -0400 From: Johannes Weiner To: azurIt Cc: Andrew Morton , Michal Hocko , David Rientjes , KAMEZAWA Hiroyuki , KOSAKI Motohiro , linux-mm@kvack.org, cgroups@vger.kernel.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [patch 0/7] improve memcg oom killer robustness v2 Message-ID: <20130910183740.GI856@cmpxchg.org> References: <20130830215852.3E5D3D66@pobox.sk> <20130902123802.5B8E8CB1@pobox.sk> <20130903204850.GA1412@cmpxchg.org> <20130904101852.58E70042@pobox.sk> <20130905115430.GB856@cmpxchg.org> <20130909151010.3A3CBC6A@pobox.sk> <20130909172849.GG856@cmpxchg.org> <20130909215917.96932098@pobox.sk> <20130909201238.GH856@cmpxchg.org> <20130910201359.D0984EFF@pobox.sk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130910201359.D0984EFF@pobox.sk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7745 Lines: 140 On Tue, Sep 10, 2013 at 08:13:59PM +0200, azurIt wrote: > >On Mon, Sep 09, 2013 at 09:59:17PM +0200, azurIt wrote: > >> >On Mon, Sep 09, 2013 at 03:10:10PM +0200, azurIt wrote: > >> >> >Hi azur, > >> >> > > >> >> >On Wed, Sep 04, 2013 at 10:18:52AM +0200, azurIt wrote: > >> >> >> > CC: "Andrew Morton" , "Michal Hocko" , "David Rientjes" , "KAMEZAWA Hiroyuki" , "KOSAKI Motohiro" , linux-mm@kvack.org, cgroups@vger.kernel.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org > >> >> >> >Hello azur, > >> >> >> > > >> >> >> >On Mon, Sep 02, 2013 at 12:38:02PM +0200, azurIt wrote: > >> >> >> >> >>Hi azur, > >> >> >> >> >> > >> >> >> >> >>here is the x86-only rollup of the series for 3.2. > >> >> >> >> >> > >> >> >> >> >>Thanks! > >> >> >> >> >>Johannes > >> >> >> >> >>--- > >> >> >> >> > > >> >> >> >> > > >> >> >> >> >Johannes, > >> >> >> >> > > >> >> >> >> >unfortunately, one problem arises: I have (again) cgroup which cannot be deleted :( it's a user who had very high memory usage and was reaching his limit very often. Do you need any info which i can gather now? > >> >> >> > > >> >> >> >Did the OOM killer go off in this group? > >> >> >> > > >> >> >> >Was there a warning in the syslog ("Fixing unhandled memcg OOM > >> >> >> >context")? > >> >> >> > >> >> >> > >> >> >> > >> >> >> Ok, i see this message several times in my syslog logs, one of them is also for this unremovable cgroup (but maybe all of them cannot be removed, should i try?). Example of the log is here (don't know where exactly it starts and ends so here is the full kernel log): > >> >> >> http://watchdog.sk/lkml/oom_syslog.gz > >> >> >There is an unfinished OOM invocation here: > >> >> > > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.715112] Fixing unhandled memcg OOM context set up from: > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.715191] [] T.1154+0x622/0x8f0 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.715274] [] mem_cgroup_cache_charge+0xbe/0xe0 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.715357] [] add_to_page_cache_locked+0x4c/0x140 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.715443] [] add_to_page_cache_lru+0x22/0x50 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.715526] [] find_or_create_page+0x73/0xb0 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.715608] [] __getblk+0xea/0x2c0 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.715692] [] __bread+0x13/0xc0 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.715774] [] ext3_get_branch+0x98/0x140 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.715859] [] ext3_get_blocks_handle+0xd7/0xdc0 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.715942] [] ext3_get_block+0xc4/0x120 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.716023] [] do_mpage_readpage+0x38a/0x690 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.716107] [] mpage_readpage+0x4f/0x70 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.716188] [] ext3_readpage+0x28/0x60 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.716268] [] filemap_fault+0x308/0x560 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.716350] [] __do_fault+0x78/0x5a0 > >> >> > Aug 22 13:15:21 server01 kernel: [1251422.716433] [] handle_pte_fault+0x84/0x940 > >> >> > > >> >> >__getblk() has this weird loop where it tries to instantiate the page, > >> >> >frees memory on failure, then retries. If the memcg goes OOM, the OOM > >> >> >path might be entered multiple times and each time leak the memcg > >> >> >reference of the respective previous OOM invocation. > >> >> > > >> >> >There are a few more find_or_create() sites that do not propagate an > >> >> >error and it's incredibly hard to find out whether they are even taken > >> >> >during a page fault. It's not practical to annotate them all with > >> >> >memcg OOM toggles, so let's just catch all OOM contexts at the end of > >> >> >handle_mm_fault() and clear them if !VM_FAULT_OOM instead of treating > >> >> >this like an error. > >> >> > > >> >> >azur, here is a patch on top of your modified 3.2. Note that Michal > >> >> >might be onto something and we are looking at multiple issues here, > >> >> >but the log excert above suggests this fix is required either way. > >> >> > >> >> > >> >> > >> >> > >> >> Johannes, is this still up to date? Thank you. > >> > > >> >No, please use the following on top of 3.2 (i.e. full replacement, not > >> >incremental to what you have): > >> > >> > >> > >> Unfortunately it didn't compile: > >> > >> > >> > >> > >> LD vmlinux.o > >> MODPOST vmlinux.o > >> WARNING: modpost: Found 4924 section mismatch(es). > >> To see full details build your kernel with: > >> 'make CONFIG_DEBUG_SECTION_MISMATCH=y' > >> GEN .version > >> CHK include/generated/compile.h > >> UPD include/generated/compile.h > >> CC init/version.o > >> LD init/built-in.o > >> LD .tmp_vmlinux1 > >> arch/x86/built-in.o: In function `do_page_fault': > >> (.text+0x26a77): undefined reference to `handle_mm_fault' > >> mm/built-in.o: In function `fixup_user_fault': > >> (.text+0x224d3): undefined reference to `handle_mm_fault' > >> mm/built-in.o: In function `__get_user_pages': > >> (.text+0x24a0f): undefined reference to `handle_mm_fault' > >> make: *** [.tmp_vmlinux1] Error 1 > > > >Oops, sorry about that. Must be configuration dependent because it > >works for me (and handle_mm_fault is obviously defined). > > > >Do you have warnings earlier in the compilation? You can use make -s > >to filter out everything but warnings. > > > >Or send me your configuration so I can try to reproduce it here. > > > >Thanks! > > > Johannes, > > the server went down early in the morning, the symptoms were similar as before - huge I/O. Can't tell what exactly happened since I wasn't able to login even on the console. But I have some info: > - applications were able to write to HDD so it wasn't deadlocked as before > - here is how it looked on graphs: http://watchdog.sk/lkml/graphs.jpg > - server wasn't responding from 6:36, it was down between 6:54 and 7:02 (i had to hard reboot it), I was awoken at 6:36 by really creepy sound from my phone ;) > - my 'load check' script successfully killed apache at 6:41 but it didn't help as you can see > - i have one screen with info from atop from time 6:44, looks like i/o was done by init (??!): http://watchdog.sk/lkml/atop.jpg (ignore swap warning, i have no swap) > - also other type of logs are available > - nothing like this happened before That IO from init looks really screwy, I have no idea what's going on on that machine, but it looks like there is more than just a memcg problem... Any chance your thirdparty security patches are concealing kernel daemon activity behind the init process and the IO is actually coming from a kernel thread like the flushers or kswapd? Are there OOM kill messages in the syslog? > What do you think? I'm now running kernel with your previous patch, not with the newest one. Which one exactly? Can you attach the diff? -- 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/