Fwd: Re: Fwd: cgroup OOM killer loop causes system to lockup (possible fix included) - now pinpointed to openssh-server

[Cal Leeming [Simplicity Media Ltd]]

  Just did some testing..

root at vicky:~# cat /var/log/auth.log | grep "Set"
May 30 21:41:05 vicky sshd[1568]: Set /proc/self/oom_adj from -17 to -17
May 30 21:41:07 vicky sshd[1574]: Set /proc/self/oom_adj to -17

root at vicky:~# ps faux | grep 1574
root      1574  0.0  0.0  70488  3404 ?        Ss   21:41   0:00  \_ 
sshd: root at pts/1

root at vicky:~# ps faux | grep "1568"
root      1568  0.0  0.0  49168  1152 ?        Ss   21:41   0:00 
/usr/sbin/sshd

In sshd.c there seems to be:
static int oom_adj_save = INT_MIN;

root at courtney:~/openssh-5.5p1# grep -R "Set %s to %d" .
./openbsd-compat/port-linux.c:          verbose("Set %s to %d", 
OOM_ADJ_PATH, oom_adj_save);

Then I tried on a server with different network card hardware (as shown 
below), and got this from the logs:

root at courtney:~/openssh-5.5p1# cat /var/log/auth.log  | grep "Set"
May 30 21:50:15 courtney sshd[4821]: Set /proc/self/oom_adj from 0 to -17
May 30 21:50:26 courtney sshd[4848]: Set /proc/self/oom_adj to 0

root at courtney:~/openssh-5.5p1# ps faux | grep "4848"
root      4848  0.0  0.0  70488  3372 ?        Ss   21:50   0:00  \_ 
sshd: root at pts/1

root at courtney:~/openssh-5.5p1# ps faux | grep "4821"
root      4821  0.0  0.0  49168  1160 ?        Ss   21:50   0:00 
/usr/sbin/sshd

root at courtney:~/openssh-5.5p1# cat /var/log/auth.log  | grep -e "Set" -e 
"oom_adjust_restore"
May 30 21:50:15 courtney sshd[4821]: Set /proc/self/oom_adj from 0 to -17
May 30 21:50:26 courtney sshd[4848]: debug3: oom_adjust_restore
May 30 21:50:26 courtney sshd[4848]: Set /proc/self/oom_adj to 0




On 30/05/2011 21:30, Cal Leeming [Simplicity Media Ltd] wrote:
> Hi all,
>
> Please find below a complete transcript of the emails between 
> debian/kernel-mm mailing lists.
>
> I've had a response back from someone on the deb mailing list stating:
>
> ====================================
> The bug seems to be that sshd does not reset the OOM adjustment before
> running the login shell (or other program).  Therefore, please report a
> bug against openssh-server.
> ====================================
>
> Therefore, I am submitting this bug to you also.. If someone would be 
> kind enough to have a flick thru all the below debug/logs, it'd be 
> very much appreciated.
>
> Cal