Messages in this thread | | | Subject | Re: Ugly rmap NULL ptr deref oopsie on hibernate (was Linux 2.6.34-rc3) | From | Peter Zijlstra <> | Date | Wed, 07 Apr 2010 10:37:19 +0200 |
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On Tue, 2010-04-06 at 08:55 -0700, Linus Torvalds wrote: > I do wonder if "page_lock_anon_vma()" should check the whole > "page_mapped()" case _after_ taking the anon_vma lock. Because if the race > happens, we're following a anon_vma list that has nothing to do with that > page (it's stilla _valid_ list, since we locked the anon_vma, but will it > be ok?) > > IOW, what is it that really keeps the anon_vma list reliable _and_ > relevant wrt the page? We know we may get a stale anon_vma, are we ok if > that anon_vma list doesn't actually have anything to do with the page any > more?
When doing the whole make i_mmap_lock/anon_vma->lock a mutex thing last week I ran into the same issue and its on my todo list to find out wth is happening there.
So yes I think we should move that validation check inside page_lock_anon_vma().
I'll cook up a patch once I'm done staring at the various funny arch mmu_gather implementations.
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