Messages in this thread | | | Subject | Re: Ugly rmap NULL ptr deref oopsie on hibernate (was Linux 2.6.34-rc3) | From | Minchan Kim <> | Date | Wed, 07 Apr 2010 01:45:27 +0900 |
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On Tue, 2010-04-06 at 09:28 -0700, Linus Torvalds wrote: > > On Wed, 7 Apr 2010, Minchan Kim wrote: > > > > > > However, that made me look at the PAGE_MIGRATION case. That seems to be > > > just broken. It's doing that page_anon_vma() + spin_lock without holding > > > any RCU locks, so there is no guarantee that anon_vma there is at all > > > valid. > > > > FYI, recently there is a patch about migration case. > > http://lkml.org/lkml/2010/4/2/145 > > No, I'm talking about rmap_walk_anon(): > > anon_vma = page_anon_vma(page); > if (!anon_vma) > return ret; > spin_lock(&anon_vma->lock); > > which seems to be simply buggy. The anon_vma may not exist any more, > because an RCU event might have really freed the page between looking it > up and locking it. > > Linus
unmap_and_move remove_migration_ptes rmap_walk rmap_walk_anon
We always has rcu_read_lock about anon page in unmap_and_move. So I think it's not buggy. What am I missing?
-- Kind regards, Minchan Kim
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