Re: mm: kernel BUG at mm/huge_memory.c:2785!

[Sasha Levin]

On 03/05/2014 08:52 AM, Kirill A. Shutemov wrote:
> Sasha Levin wrote:
> > On 02/27/2014 10:03 AM, Kirill A. Shutemov wrote:
> > > Sasha Levin wrote:
> > > > > Hi all,
> > > > >
> > > > > While fuzzing with trinity inside a KVM tools guest running latest -next kernel I've stumbled on the
> > > > > following spew:
> > > > >
> > > > > [ 1428.146261] kernel BUG at mm/huge_memory.c:2785!
> > > Hm, interesting.
> > >
> > > It seems we either failed to split huge page on vma split or it
> > > materialized from under us. I don't see how it can happen:
> > >
> > >     - it seems we do the right thing with vma_adjust_trans_huge() in
> > >       __split_vma();
> > >     - we hold ->mmap_sem all the way from vm_munmap(). At least I don't see
> > >       a place where we could drop it;
> > >
> > > Andrea, any ideas?
> >
> > And a somewhat related issue (please correct me if I'm wrong):
>
> Yeah. Looks similar. And I still have no idea how it could happened.
>
> Do you trinity logs for the crash?

I can't get it to reproduce with trinity logging enabled, I guess it makes it harder for
the race to occur.

I'll keep it running through the night but don't really have high hopes.


Thanks,
Sasha

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