lkml.org 
[lkml]   [2009]   [Nov]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [BUGFIX][PATCH -mmotm] memcg: avoid oom-killing innocent task in case of use_hierarchy
On Tue, 24 Nov 2009 19:01:54 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> On Tue, Nov 24, 2009 at 11:27 AM, Daisuke Nishimura
> <nishimura@mxp.nes.nec.co.jp> wrote:
> > task_in_mem_cgroup(), which is called by select_bad_process() to check whether
> > a task can be a candidate for being oom-killed from memcg's limit, checks
> > "curr->use_hierarchy"("curr" is the mem_cgroup the task belongs to).
> >
> > But this check return true(it's false positive) when:
> >
> >        <some path>/00          use_hierarchy == 0      <- hitting limit
> >          <some path>/00/aa     use_hierarchy == 1      <- "curr"
> >
> > This leads to killing an innocent task in 00/aa. This patch is a fix for this
> > bug. And this patch also fixes the arg for mem_cgroup_print_oom_info(). We
> > should print information of mem_cgroup which the task being killed, not current,
> > belongs to.
> >
>
> Quick Question: What happens if <some path>/00 has no tasks in it
> after your patches?
>
Nothing would happen because <some path>/00 never hit its limit.

The bug that this patch fixes is:

- create a dir <some path>/00 and set some limits.
- create a sub dir <some path>/00/aa w/o any limits, and enable hierarchy.
- run some programs in both in 00 and 00/aa. programs in 00 should be
big enough to cause oom by its limit.
- when oom happens by 00's limit, tasks in 00/aa can also be killed.


Regards,
Daisuke Nishimura.
--
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/

\
 
 \ /
  Last update: 2009-11-24 15:59    [W:0.098 / U:0.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site