lkml.org 
[lkml]   [2011]   [Dec]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 RESEND] oom: fix integer overflow of points in oom_badness
On Fri, Dec 02, 2011 at 11:00:19AM -0800, Greg KH wrote:
> On Fri, Dec 02, 2011 at 06:45:27PM +0100, Frantisek Hrbata wrote:
> > An integer overflow will happen on 64bit archs if task's sum of rss, swapents
> > and nr_ptes exceeds (2^31)/1000 value. This was introduced by commit
> >
> > f755a04 oom: use pte pages in OOM score
> >
> > where the oom score computation was divided into several steps and it's no
> > longer computed as one expression in unsigned long(rss, swapents, nr_pte are
> > unsigned long), where the result value assigned to points(int) is in
> > range(1..1000). So there could be an int overflow while computing
> >
> > 176 points *= 1000;
> >
> > and points may have negative value. Meaning the oom score for a mem hog task
> > will be one.
> >
> > 196 if (points <= 0)
> > 197 return 1;
> >
> > For example:
> > [ 3366] 0 3366 35390480 24303939 5 0 0 oom01
> > Out of memory: Kill process 3366 (oom01) score 1 or sacrifice child
> >
> > Here the oom1 process consumes more than 24303939(rss)*4096~=92GB physical
> > memory, but it's oom score is one.
> >
> > In this situation the mem hog task is skipped and oom killer kills another and
> > most probably innocent task with oom score greater than one.
> >
> > The points variable should be of type long instead of int to prevent the int
> > overflow.
> >
> > Signed-off-by: Frantisek Hrbata <fhrbata@redhat.com>
> > Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> > Acked-by: Oleg Nesterov <oleg@redhat.com>
> > Acked-by: David Rientjes <rientjes@google.com>
> > Cc: stable@kernel.org [2.6.36+]
>
> For what it's worth, the stable address has changed to
> stable@vger.kernel.org so you might want to fix that up in future
> submissions.

I was not aware of this change.

>
> I still catch patches that are tagged with this marking, but you will
> not end up posting stuff to the list this way :)

Duly noted :)

>
> thanks,

Thanks Greg!

>
> greg k-h

--
Frantisek Hrbata


\
 
 \ /
  Last update: 2011-12-02 21:49    [W:1.029 / U:24.700 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site