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SubjectRe: [PATCH -v2] rmap: make anon_vma_prepare link in all the anon_vmas of a mergeable VMA
From: Linus Torvalds <>
Date: Sat, Apr 10, 2010 at 02:30:49PM -0700

> On Sat, 10 Apr 2010, Borislav Petkov wrote:
> >
> > Damn, nope, still no joy :(. It looked like it was fixed but one of the
> > test was to hibernate right after the 3 kvm guests were shut down and I
> > guess the mem freeing pattern kinda hits it where it most hurts.
> Damn, I really hoped that was it. Three independent bugs found and fixed,
> and still no joy? Oh well.

Yep, I'll redo the testing tomorrow, so that we are sure that even with
the _three_ bugs fixed we still hit the funky list element issue.

> > By the way, do we want to create a new thread - the mailchain is off the
> > screen limits of my netbook :)
> I prefer to keep it in one thread so that they all show up together if I
> need to, but feel free to start a new one. Not a biggie.

I'll keep the thread then - I didn't know it mattered. Mine was just a
suggestion, nevermind.

> > [ 647.492781] BUG: unable to handle kernel NULL pointer dereference at (null)
> > [ 647.493001] IP: [<ffffffff810c60a0>] page_referenced+0xee/0x1dc
> Well, it sure is consistent. I'll start to think about what else could go
> wrong..

Which could mean that even with those issues fixed, the real issue is
yet something else. Because obviously the fixes you throw at it don't
seem to change it - even the traces remain consistent across tests.
And if it is use-after-free case, the funny patterns could be some
shifted SLUB poison values which we happen to "see" through the dangling
pointer... I dunno.



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