After submitting this problem to Kernel mailing list, I found a strange
(and even more curious problem).
I attempted to run both kernels on two seperate installs of Debian (both
6.0), but slightly different in packages.. One install did not have the
OOM problem, yet the other one did.. And they both ran the same kernel,
the same LXC container etc..
I have a feeling this may be a Debian bug..? Further to back up these
claims:
Working server:
root@courtney.internal [/mnt/encstore/lxc/github01.rootfs] > for x in
`find /proc -iname 'oom_adj' | xargs grep "\-17" | awk -F '/' '{print
$3}'` ; do ps -p $x u --no-headers ; done
grep: /proc/3090/task/3090/oom_adj: No such file or directory
grep: /proc/3090/oom_adj: No such file or directory
root 804 0.0 0.0 16992 1112 ? S<s Mar17 0:00 udevd
--daemon
root 804 0.0 0.0 16992 1112 ? S<s Mar17 0:00 udevd
--daemon
root 25536 0.0 0.0 49164 1100 ? Ss Apr05 0:00
/usr/sbin/sshd
root 25536 0.0 0.0 49164 1100 ? Ss Apr05 0:00
/usr/sbin/sshd
root 32173 0.0 0.0 16988 960 ? S< 21:53 0:00 udevd
--daemon
root 32173 0.0 0.0 16988 960 ? S< 21:53 0:00 udevd
--daemon
root 32174 0.0 0.0 16988 916 ? S< 21:53 0:00 udevd
--daemon
root 32174 0.0 0.0 16988 916 ? S< 21:53 0:00 udevd
--daemon
Broken server:
root@vicky [/var] > for x in `find /proc -iname 'oom_adj' | xargs grep
"\-17" | awk -F '/' '{print $3}'` ; do ps -p $x u --no-headers ; done
grep: /proc/4597/task/4597/oom_adj: No such file or directory
grep: /proc/4597/oom_adj: No such file or directory
root 889 0.0 0.0 16788 860 ? S<s 09:10 0:00 udevd
--daemon
root 889 0.0 0.0 16788 860 ? S<s 09:10 0:00 udevd
--daemon
root 1104 0.0 0.0 17228 1200 ? S< 09:10 0:00 udevd
--daemon
root 1104 0.0 0.0 17228 1200 ? S< 09:10 0:00 udevd
--daemon
root 1141 0.0 0.0 17120 1128 ? S< 09:10 0:00 udevd
--daemon
root 1141 0.0 0.0 17120 1128 ? S< 09:10 0:00 udevd
--daemon
root 2745 0.0 0.0 49168 1168 ? Ss 09:10 0:00
/usr/sbin/sshd
root 2745 0.0 0.0 49168 1168 ? Ss 09:10 0:00
/usr/sbin/sshd
root 2750 0.0 0.0 76672 3360 ? Ss 09:11 0:00 sshd:
foxx [priv]
root 2750 0.0 0.0 76672 3360 ? Ss 09:11 0:00 sshd:
foxx [priv]
foxx 2754 0.0 0.0 76672 1636 ? S 09:11 0:00 sshd:
foxx@pts/0
foxx 2754 0.0 0.0 76672 1636 ? S 09:11 0:00 sshd:
foxx@pts/0
foxx 2755 0.0 0.0 123984 1984 pts/0 Ss 09:11 0:00 -bash
foxx 2755 0.0 0.0 123984 1984 pts/0 Ss 09:11 0:00 -bash
root 2760 0.0 0.0 127176 1244 pts/0 S 09:11 0:00 sudo su
root 2760 0.0 0.0 127176 1244 pts/0 S 09:11 0:00 sudo su
root 2761 0.0 0.0 147820 1328 pts/0 S 09:11 0:00 su
root 2761 0.0 0.0 147820 1328 pts/0 S 09:11 0:00 su
root 2762 0.0 0.0 124084 2152 pts/0 S 09:11 0:00 bash
root 2762 0.0 0.0 124084 2152 pts/0 S 09:11 0:00 bash
Notice how the sshd user instances on the broken server are set to -17,
yet the sshd user instances on the working server, are not :S
Any input from anyone on the below would be VERY much appreciated.
Cal
-------- Original Message --------
Subject: Re: Fwd: cgroup OOM killer loop causes system to lockup
(possible fix included)
Date: Sun, 29 May 2011 23:24:07 +0100
From: Cal Leeming [Simplicity Media Ltd]
<cal.leem...@simplicitymedialtd.co.uk>
Organization: Simplicity Media Ltd
To: linux-ker...@vger.kernel.org, linux-rt-us...@vger.kernel.org
Some further logs:
./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.369927] redis-server
invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17
./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.369939]
[<ffffffff810b12b7>] ? oom_kill_process+0x82/0x283
./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.399285] redis-server
invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17
./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.399296]
[<ffffffff810b12b7>] ? oom_kill_process+0x82/0x283
./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.428690] redis-server
invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17
./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.428702]
[<ffffffff810b12b7>] ? oom_kill_process+0x82/0x283
./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.487696] redis-server
invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17
./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.487708]
[<ffffffff810b12b7>] ? oom_kill_process+0x82/0x283
./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.517023] redis-server
invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17
./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.517035]
[<ffffffff810b12b7>] ? oom_kill_process+0x82/0x283
./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.546379] redis-server
invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17
./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.546391]
[<ffffffff810b12b7>] ? oom_kill_process+0x82/0x283
./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.310789] redis-server
invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17
./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.310804]
[<ffffffff810b12b7>] ? oom_kill_process+0x82/0x283
./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.369918] redis-server
invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17
./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.369930]
[<ffffffff810b12b7>] ? oom_kill_process+0x82/0x283
./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.399284] redis-server
invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17
./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.399296]
[<ffffffff810b12b7>] ? oom_kill_process+0x82/0x283
./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.433634] redis-server
invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17
./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.433648]
[<ffffffff810b12b7>] ? oom_kill_process+0x82/0x283
./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.463947] redis-server
invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17
./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.463959]
[<ffffffff810b12b7>] ? oom_kill_process+0x82/0x283
./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.493439] redis-server
invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17
./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.493451]
[<ffffffff810b12b7>] ? oom_kill_process+0x82/0x283
On 29/05/2011 22:50, Cal Leeming [Simplicity Media Ltd] wrote:
First of all, my apologies if I have submitted this problem to the
wrong place, spent 20 minutes trying to figure out where it needs to
be sent, and was still none the wiser.
The problem is related to applying memory limitations within a cgroup.
If the OOM killer kicks in, it gets stuck in a loop where it tries to
kill a process which has an oom_adj of -17. This causes an infinite
loop, which in turn locks up the system.
May 30 03:13:08 vicky kernel: [ 1578.117055] Memory cgroup out of
memory: kill process 6016 (java) score 0 or a child
May 30 03:13:08 vicky kernel: [ 1578.117154] Memory cgroup out of
memory: kill process 6016 (java) score 0 or a child
May 30 03:13:08 vicky kernel: [ 1578.117248] Memory cgroup out of
memory: kill process 6016 (java) score 0 or a child
May 30 03:13:08 vicky kernel: [ 1578.117343] Memory cgroup out of
memory: kill process 6016 (java) score 0 or a child
May 30 03:13:08 vicky kernel: [ 1578.117441] Memory cgroup out of
memory: kill process 6016 (java) score 0 or a child
root@vicky [/home/foxx]> uname -a
Linux vicky 2.6.32.41-grsec #3 SMP Mon May 30 02:34:43 BST 2011 x86_64
GNU/Linux
(this happens on both the grsec patched and non patched 2.6.32.41 kernel)
When this is encountered, the memory usage across the whole server is
still within limits (not even hitting swap).
The memory configuration for the cgroup/lxc is:
lxc.cgroup.memory.limit_in_bytes = 3000M
lxc.cgroup.memory.memsw.limit_in_bytes = 3128M
Now, what is even more strange, is that when running under the
2.6.32.28 kernel (both patched and unpatched), this problem doesn't
happen. However, there is a slight difference between the two kernels.
The 2.6.32.28 kernel gives a default of 0 in the /proc/X/oom_adj,
where as the 2.6.32.41 gives a default of -17. I suspect this is the
root cause of why it's showing in the later kernel, but not the earlier.
To test this theory, I started up the lxc on both servers, and then
ran a one liner which showed me all the processes with an oom_adj of -17:
(the below is the older/working kernel)
root@courtney.internal [/mnt/encstore/lxc]> uname -a
Linux courtney.internal 2.6.32.28-grsec #3 SMP Fri Feb 18 16:09:07 GMT
2011 x86_64 GNU/Linux
root@courtney.internal [/mnt/encstore/lxc]> for x in `find /proc
-iname 'oom_adj' | xargs grep "\-17" | awk -F '/' '{print $3}'` ; do
ps -p $x --no-headers ; done
grep: /proc/1411/task/1411/oom_adj: No such file or directory
grep: /proc/1411/oom_adj: No such file or directory
804 ? 00:00:00 udevd
804 ? 00:00:00 udevd
25536 ? 00:00:00 sshd
25536 ? 00:00:00 sshd
31861 ? 00:00:00 sshd
31861 ? 00:00:00 sshd
32173 ? 00:00:00 udevd
32173 ? 00:00:00 udevd
32174 ? 00:00:00 udevd
32174 ? 00:00:00 udevd
(the below is the newer/broken kernel)
root@vicky [/mnt/encstore/ssd/kernel/linux-2.6.32.41]> uname -a
Linux vicky 2.6.32.41-grsec #3 SMP Mon May 30 02:34:43 BST 2011 x86_64
GNU/Linux
root@vicky [/mnt/encstore/ssd/kernel/linux-2.6.32.41]> for x in
`find /proc -iname 'oom_adj' | xargs grep "\-17" | awk -F '/' '{print
$3}'` ; do ps -p $x --no-headers ; done
grep: /proc/3118/task/3118/oom_adj: No such file or directory
grep: /proc/3118/oom_adj: No such file or directory
895 ? 00:00:00 udevd
895 ? 00:00:00 udevd
1091 ? 00:00:00 udevd
1091 ? 00:00:00 udevd
1092 ? 00:00:00 udevd
1092 ? 00:00:00 udevd
2596 ? 00:00:00 sshd
2596 ? 00:00:00 sshd
2608 ? 00:00:00 sshd
2608 ? 00:00:00 sshd
2613 ? 00:00:00 sshd
2613 ? 00:00:00 sshd
2614 pts/0 00:00:00 bash
2614 pts/0 00:00:00 bash
2620 pts/0 00:00:00 sudo
2620 pts/0 00:00:00 sudo
2621 pts/0 00:00:00 su
2621 pts/0 00:00:00 su
2622 pts/0 00:00:00 bash
2622 pts/0 00:00:00 bash
2685 ? 00:00:00 lxc-start
2685 ? 00:00:00 lxc-start
2699 ? 00:00:00 init
2699 ? 00:00:00 init
2939 ? 00:00:00 rc
2939 ? 00:00:00 rc
2942 ? 00:00:00 startpar
2942 ? 00:00:00 startpar
2964 ? 00:00:00 rsyslogd
2964 ? 00:00:00 rsyslogd
2964 ? 00:00:00 rsyslogd
2964 ? 00:00:00 rsyslogd
2980 ? 00:00:00 startpar
2980 ? 00:00:00 startpar
2981 ? 00:00:00 ctlscript.sh
2981 ? 00:00:00 ctlscript.sh
3016 ? 00:00:00 cron
3016 ? 00:00:00 cron
3025 ? 00:00:00 mysqld_safe
3025 ? 00:00:00 mysqld_safe
3032 ? 00:00:00 sshd
3032 ? 00:00:00 sshd
3097 ? 00:00:00 mysqld.bin
3097 ? 00:00:00 mysqld.bin
3097 ? 00:00:00 mysqld.bin
3097 ? 00:00:00 mysqld.bin
3097 ? 00:00:00 mysqld.bin
3097 ? 00:00:00 mysqld.bin
3097 ? 00:00:00 mysqld.bin
3097 ? 00:00:00 mysqld.bin
3097 ? 00:00:00 mysqld.bin
3097 ? 00:00:00 mysqld.bin
3113 ? 00:00:00 ctl.sh
3113 ? 00:00:00 ctl.sh
3115 ? 00:00:00 sleep
3115 ? 00:00:00 sleep
3116 ? 00:00:00 .memcached.bin
3116 ? 00:00:00 .memcached.bin
As you can see, it is clear that the newer kernel is setting -17 by
default, which in turn is causing the OOM killer loop.
So I began to try and find what may have caused this problem by
comparing the two sources...
I checked the code for all references to 'oom_adj' and 'oom_adjust' in
both code sets, but found no obvious differences:
grep -R -e oom_adjust -e oom_adj . | sort | grep -R -e oom_adjust -e
oom_adj
Then I checked for references to "-17" in all .c and .h files, and
found a couple of matches, but only one obvious one:
grep -R "\-17" . | grep -e ".c:" -e ".h:" -e "\-17" | wc -l
./include/linux/oom.h:#define OOM_DISABLE (-17)
But again, a search for OOM_DISABLE came up with nothing obvious...
In a last ditch attempt, I did a search for all references to 'oom'
(case-insensitive) in both code bases, then compared the two:
root@annabelle [~/lol/linux-2.6.32.28]> grep -i -R "oom" . | sort -n
> /tmp/annabelle.oom_adj
root@vicky [/mnt/encstore/ssd/kernel/linux-2.6.32.41]> grep -i -R
"oom" . | sort -n> /tmp/vicky.oom_adj
and this brought back (yet again) nothing obvious..
root@vicky [/mnt/encstore/ssd/kernel/linux-2.6.32.41]> md5sum
./include/linux/oom.h
2a32622f6cd38299fc2801d10a9a3ea8 ./include/linux/oom.h
root@annabelle [~/lol/linux-2.6.32.28]> md5sum ./include/linux/oom.h
2a32622f6cd38299fc2801d10a9a3ea8 ./include/linux/oom.h
root@vicky [/mnt/encstore/ssd/kernel/linux-2.6.32.41]> md5sum
./mm/oom_kill.c
1ef2c2bec19868d13ec66ec22033f10a ./mm/oom_kill.c
root@annabelle [~/lol/linux-2.6.32.28]> md5sum ./mm/oom_kill.c
1ef2c2bec19868d13ec66ec22033f10a ./mm/oom_kill.c
Could anyone please shed some light as to why the default oom_adj is
set to -17 now (and where it is actually set)? From what I can tell,
the fix for this issue will either be:
1. Allow OOM killer to override the decision of ignoring oom_adj ==
-17 if an unrecoverable loop is encountered.
2. Change the default back to 0.
Again, my apologies if this bug report is slightly unorthodox, or
doesn't follow usual procedure etc. I can assure you I have tried my
absolute best to give all the necessary information though.
Cal
