Messages in this thread | | | Date | Wed, 4 Jan 2012 15:16:32 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] mm: hugetlb: undo change to page mapcount in fault handler |
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On Fri, 23 Dec 2011 21:00:41 +0800 Hillf Danton <dhillf@gmail.com> wrote:
> Page mapcount should be updated only if we are sure that the page ends > up in the page table otherwise we would leak if we couldn't COW due to > reservations or if idx is out of bounds.
It would be much nicer if we could run vma_needs_reservation() before even looking up or allocating the page.
And afaict the interface is set up to do that: you run vma_needs_reservation() before allocating the page and then vma_commit_reservation() afterwards.
But hugetlb_no_page() and hugetlb_fault() appear to have forgotten to run vma_commit_reservation() altogether. Why isn't this as busted as it appears to be?
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