Messages in this thread | | | Date | Fri, 23 Apr 2010 08:52:03 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH 04/14] mm,migration: Allow the migration of PageSwapCache pages |
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On Thu, 22 Apr 2010 14:40:46 -0500 (CDT) Christoph Lameter <cl@linux.com> wrote:
> On Thu, 22 Apr 2010, Mel Gorman wrote: > > > vma_adjust() is updating anon VMA information without any locks taken. > > In constract, file-backed mappings use the i_mmap_lock. This lack of > > locking can result in races with page migration. During rmap_walk(), > > vma_address() can return -EFAULT for an address that will soon be valid. > > This leaves a dangling migration PTE behind which can later cause a > > BUG_ON to trigger when the page is faulted in. > > Isnt this also a race with reclaim / swap? > Yes, it's also race in reclaim/swap ... page_referenced() try_to_unmap(). rmap_walk() <==== we hit this case.
But above 2 are not considered to be critical.
I'm not sure how this race affect KSM.
Thanks, -Kame
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