Re: khugepaged / firefox going wild in 3.18-rc

David Rientjes
2014-11-05T00:00:42Z

On Wed, 5 Nov 2014, Norbert Preining wrote:

> Dear all,
>
> (please Cc)
>
> since 3.18-rc started, regularly, but unpredictably, firefox
> (Debian iceweasel) goes completely boom to 100% CPU, and there
> is also a kernel task khugepaged doing the same.
>
> I need to kill firefox, or better the X session to get it back to normal.
>
> THe logs don't show any strange output
>
> top's top process:
>
> 27021 norbert 20 0 1351536 449868 88788 R 100.4 5.6 4:46.16 iceweasel
> 35 root 39 19 0 0 0 R 100.0 0.0 2:41.10 khugepaged
>
> Switching back to 3.17 does Not* exhibit the same behaviour.
>
> Is this a bug in Firefox/Iceweasel, or is there something luring in the
> kernel.
>

If you have the ability to kill your X session, then you presumably are
able to capture /proc/pid/stack for these pids to see where it is busy.
It might also be helpful to see how the grep ^thp_ /proc/vmstat and
grep ^compact_ /proc/vmstat counters change over time.