Re: Ugly rmap NULL ptr deref oopsie on hibernate (was Linux 2.6.34-rc3)

From: Rik van Riel
Date: Tue Apr 06 2010 - 21:20:21 EST

On 04/06/2010 08:10 PM, Linus Torvalds wrote:

That said, the code that _really_ confuses me is the stuff that uses
"anon_vma_clone()". Could you please also explain the code flow of
vma_adjust() to mere mortals, please?

That's easier said than done. I spent 3 days with pen and paper,
going over that code before I made the anon_vma changes, first
verifying that the code is indeed correct and then figuring out
how I could make the anon_vma changes safely.

I am not happy with the complexity of the code around vma_adjust,
but could not find a way to simplify it and still keep merging
VMAs the way we do.

My largest change to vma_adjust was moving some code closer to
the beginning of the function, so I could bail out if the
allocation failed, without making change to the vma...

I suspect Borislav is sleeping. But at least we have a patch for him to
test when he wakes up ;)

I am looking forward to the test results.

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