Re: [PATCH] ksm: fix race between ksmd and exiting task

[Chris Wright]

* Andrea Righi (andrea@xxxxxxxxxxxxxxx) wrote:
> On Thu, Jun 02, 2011 at 10:35:49AM -0700, Chris Wright wrote:
> > Andrea Righi reported a case where an exiting task can race against
> > ksmd.
> > 
> > ksm_scan.mm_slot == the only registered mm
> > CPU 1 (bug program)		CPU 2 (ksmd)
> >  				list_empty() is false
> > lock
> > ksm_scan.mm_slot
> > list_del
> > unlock
> >  				slot == &ksm_mm_head (but list is now empty_)
> > 
> > Close this race by revalidating that the new slot is not simply the list
> > head again.
> 
> I confirm this fixes the problem on my side.
> 
> Tested-by: Andrea Righi <andrea@xxxxxxxxxxxxxxx>

Great, thanks for verifying.

thanks,
-chris
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