Re: khugepaged / firefox going wild in 3.18-rc

[David Rientjes]

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.
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