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To: =?utf-8?q?Johannes_Weiner?= <hannes@cmpxchg.org>
Subject: =?utf-8?q?Re=3A_=5Bpatch_0=2F7=5D_improve_memcg_oom_killer_robustness_v2?=
Date: Tue, 10 Sep 2013 21:32:53 +0200
From: "azurIt" <azurit@pobox.sk>
Cc: =?utf-8?q?Andrew_Morton?= <akpm@linux-foundation.org>,
        =?utf-8?q?Michal_Hocko?= <mhocko@suse.cz>,
        =?utf-8?q?David_Rientjes?= <rientjes@google.com>,
        =?utf-8?q?KAMEZAWA_Hiroyuki?= <kamezawa.hiroyu@jp.fujitsu.com>,
        =?utf-8?q?KOSAKI_Motohiro?= <kosaki.motohiro@jp.fujitsu.com>,
        <linux-mm@kvack.org>, <cgroups@vger.kernel.org>, <x86@kernel.org>,
        <linux-arch@vger.kernel.org>, <linux-kernel@vger.kernel.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> <20130910183740.GI856@cmpxchg.org>
In-Reply-To: <20130910183740.GI856@cmpxchg.org>
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>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" <akpm@linux-foundation.org>, "Michal Hocko" <mhocko@suse.cz>, "David Rientjes" <rientjes@google.com>, "KAMEZAWA Hiroyuki" <kamezawa.hiroyu@jp.fujitsu.com>, "KOSAKI Motohiro" <kosaki.motohiro@jp.fujitsu.com>, 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]  [<ffffffff811105c2>] T.1154+0x622/0x8f0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715274]  [<ffffffff8111153e>] mem_cgroup_cache_charge+0xbe/0xe0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715357]  [<ffffffff810cf31c>] add_to_page_cache_locked+0x4c/0x140
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715443]  [<ffffffff810cf432>] add_to_page_cache_lru+0x22/0x50
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715526]  [<ffffffff810cfdd3>] find_or_create_page+0x73/0xb0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715608]  [<ffffffff811493ba>] __getblk+0xea/0x2c0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715692]  [<ffffffff8114ca73>] __bread+0x13/0xc0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715774]  [<ffffffff81196968>] ext3_get_branch+0x98/0x140
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715859]  [<ffffffff81197557>] ext3_get_blocks_handle+0xd7/0xdc0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715942]  [<ffffffff81198304>] ext3_get_block+0xc4/0x120
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.716023]  [<ffffffff81155c3a>] do_mpage_readpage+0x38a/0x690
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.716107]  [<ffffffff81155f8f>] mpage_readpage+0x4f/0x70
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.716188]  [<ffffffff811973a8>] ext3_readpage+0x28/0x60
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.716268]  [<ffffffff810cfa48>] filemap_fault+0x308/0x560
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.716350]  [<ffffffff810ef898>] __do_fault+0x78/0x5a0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.716433]  [<ffffffff810f2ab4>] 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?




I really cannot tell but I never ever saw this before and i'm using all of my patches for several years. Here are all patches which i'm using right now (+ your patch):
http://watchdog.sk/lkml/patches3




>Are there OOM kill messages in the syslog?



Here is full kernel log between 6:00 and 7:59:
http://watchdog.sk/lkml/kern6.log



>> 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?



I meant, the problem above occured on kernel with your latest patch:
http://watchdog.sk/lkml/7-2-memcg-fix.patch

but after i had to reboot the server i booted the kernel with your previous patch:
http://watchdog.sk/lkml/7-1-memcg-fix.patch


azur

From mboxrd@z Thu Jan  1 00:00:00 1970
From: "azurIt" <azurit@pobox.sk>
Subject: =?utf-8?q?Re=3A_=5Bpatch_0=2F7=5D_improve_memcg_oom_killer_robustness_v2?=
Date: Tue, 10 Sep 2013 21:32:53 +0200
Message-ID: <20130910213253.A1E666C5@pobox.sk>
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> <20130910183740.GI856@cmpxchg.org>
Mime-Version: 1.0
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Return-path: <owner-linux-mm@kvack.org>
In-Reply-To: <20130910183740.GI856@cmpxchg.org>
Sender: owner-linux-mm@kvack.org
To: =?utf-8?q?Johannes_Weiner?= <hannes@cmpxchg.org>
Cc: =?utf-8?q?Andrew_Morton?= <akpm@linux-foundation.org>, =?utf-8?q?Michal_Hocko?= <mhocko@suse.cz>, =?utf-8?q?David_Rientjes?= <rientjes@google.com>, =?utf-8?q?KAMEZAWA_Hiroyuki?= <kamezawa.hiroyu@jp.fujitsu.com>, =?utf-8?q?KOSAKI_Motohiro?= <kosaki.motohiro@jp.fujitsu.com>, linux-mm@kvack.org, cgroups@vger.kernel.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
List-Id: linux-arch.vger.kernel.org

>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" <akpm@linux-foundation.org>, "Michal Ho=
cko" <mhocko@suse.cz>, "David Rientjes" <rientjes@google.com>, "KAMEZAWA =
Hiroyuki" <kamezawa.hiroyu@jp.fujitsu.com>, "KOSAKI Motohiro" <kosaki.mot=
ohiro@jp.fujitsu.com>, linux-mm@kvack.org, cgroups@vger.kernel.org, x86@k=
ernel.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 gath=
er now?
>> >> >> >> >
>> >> >> >> >Did the OOM killer go off in this group?
>> >> >> >> >
>> >> >> >> >Was there a warning in the syslog ("Fixing unhandled memcg O=
OM
>> >> >> >> >context")?
>> >> >> >>=20
>> >> >> >>=20
>> >> >> >>=20
>> >> >> >> Ok, i see this message several times in my syslog logs, one o=
f 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 unha=
ndled memcg OOM context set up from:
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715191]  [<ffffffff=
811105c2>] T.1154+0x622/0x8f0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715274]  [<ffffffff=
8111153e>] mem_cgroup_cache_charge+0xbe/0xe0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715357]  [<ffffffff=
810cf31c>] add_to_page_cache_locked+0x4c/0x140
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715443]  [<ffffffff=
810cf432>] add_to_page_cache_lru+0x22/0x50
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715526]  [<ffffffff=
810cfdd3>] find_or_create_page+0x73/0xb0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715608]  [<ffffffff=
811493ba>] __getblk+0xea/0x2c0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715692]  [<ffffffff=
8114ca73>] __bread+0x13/0xc0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715774]  [<ffffffff=
81196968>] ext3_get_branch+0x98/0x140
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715859]  [<ffffffff=
81197557>] ext3_get_blocks_handle+0xd7/0xdc0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.715942]  [<ffffffff=
81198304>] ext3_get_block+0xc4/0x120
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.716023]  [<ffffffff=
81155c3a>] do_mpage_readpage+0x38a/0x690
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.716107]  [<ffffffff=
81155f8f>] mpage_readpage+0x4f/0x70
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.716188]  [<ffffffff=
811973a8>] ext3_readpage+0x28/0x60
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.716268]  [<ffffffff=
810cfa48>] filemap_fault+0x308/0x560
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.716350]  [<ffffffff=
810ef898>] __do_fault+0x78/0x5a0
>> >> >> >  Aug 22 13:15:21 server01 kernel: [1251422.716433]  [<ffffffff=
810f2ab4>] handle_pte_fault+0x84/0x940
>> >> >> >
>> >> >> >__getblk() has this weird loop where it tries to instantiate th=
e 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 mem=
cg
>> >> >> >reference of the respective previous OOM invocation.
>> >> >> >
>> >> >> >There are a few more find_or_create() sites that do not propaga=
te an
>> >> >> >error and it's incredibly hard to find out whether they are eve=
n taken
>> >> >> >during a page fault.  It's not practical to annotate them all w=
ith
>> >> >> >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 tr=
eating
>> >> >> >this like an error.
>> >> >> >
>> >> >> >azur, here is a patch on top of your modified 3.2.  Note that M=
ichal
>> >> >> >might be onto something and we are looking at multiple issues h=
ere,
>> >> >> >but the log excert above suggests this fix is required either w=
ay.
>> >> >>=20
>> >> >>=20
>> >> >>=20
>> >> >>=20
>> >> >> 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):
>> >>=20
>> >>=20
>> >>=20
>> >> Unfortunately it didn't compile:
>> >>=20
>> >>=20
>> >>=20
>> >>=20
>> >>   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=3Dy'
>> >>   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!
>>=20
>>=20
>> Johannes,
>>=20
>> the server went down early in the morning, the symptoms were similar a=
s 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 b=
efore
>>  - 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 di=
dn'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 w=
arning, 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?




I really cannot tell but I never ever saw this before and i'm using all o=
f my patches for several years. Here are all patches which i'm using righ=
t now (+ your patch):
http://watchdog.sk/lkml/patches3




>Are there OOM kill messages in the syslog?



Here is full kernel log between 6:00 and 7:59:
http://watchdog.sk/lkml/kern6.log



>> What do you think? I'm now running kernel with your previous patch, no=
t with the newest one.
>
>Which one exactly?  Can you attach the diff?



I meant, the problem above occured on kernel with your latest patch:
http://watchdog.sk/lkml/7-2-memcg-fix.patch

but after i had to reboot the server i booted the kernel with your previo=
us patch:
http://watchdog.sk/lkml/7-1-memcg-fix.patch


azur

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