Re: [LTP] Regarding memcg control testcase (mem_process.c)

[Jan Stancek <jstancek@redhat.com>]

----- Original Message -----
> From: "Manjeet Pawar" <manjeet.p@samsung.com>
> To: "Jan Stancek" <jstancek@redhat.com>, ltp-list@lists.sourceforge.net
> Cc: "AJEET YADAV" <ajeet.y@samsung.com>, "PANKAJ MISHRA" <pankaj.m@samsung.com>
> Sent: Wednesday, 29 July, 2015 5:54:55 AM
> Subject: Re: Re: [LTP]  Regarding memcg control  testcase (mem_process.c)
> 
> Hello Jan,
> After doing analysis, I found that When memory hog process (mem_process)
> tries to mmap double the memory of the cgroup limit which is 4096 . I am
> getting OOM in that situation and send kill signal to process (which is
> expected behaviour) . But it could not kill the process and
>  it sets the process state to uninterrupted sleep state.
> 
> To get this OOM , i need to change oom_adj value of the process '208' from
> -17 to -16. If i dont do this, I dont get OOM and process always stuck at
> mmap and try to allocate 8192 Bytes of memory.

That explains it, -17 means OOM is disabled:
#define OOM_DISABLE (-17)

> logs:-
> [2-74.5749] Memory cgroup out of memory: Kill process 208 (mem_process) score
> 147000 or sacrifice child
> [2-74.5840] Killed process 208 (mem_process) total-vm:2704kB, anon-rss:80kB,
> file-rss:484kB
> by mmap is -1237753856
> Warning: bad syntax, perhaps a bogus '-'? See /usr/share/doc/procps-3.2.8/FAQ
> root       208 39.6  0.0   2704   564 ?        D    00:01   0:02 mem_process
> -m 8192  // D - means uninterrupted sleep
> root       215  0.0  0.0   2412   584 ?        S    00:01   0:00 grep -r 208

No idea why it's getting stuck though. I'd try with oom_adj == 0. If that makes
no difference, /proc/<pid>/stack might give some additional clues.

Do you see similar behaviour with other OOM testcases?

Regards,
Jan

> 
> I am using 3.10.84 kernel. LTP is of latest  version (ltp-full-20150420)
> 
> Regards
> Manjeet
> 
> ------- Original Message -------
> Sender : Jan Stancek<jstancek@redhat.com>
> Date : Jul 27, 2015 17:32 (GMT+09:00)
> Title : Re: [LTP] Regarding memcg control testcase (mem_process.c)
> 
> 
> 
> 

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