Re: [PATCH 2/3] mm/hugetlb: take refcount under page table lock in follow_huge_pmd()

[Naoya Horiguchi]

On Mon, Jul 28, 2014 at 04:02:31PM -0700, David Rientjes wrote:
> On Mon, 28 Jul 2014, Naoya Horiguchi wrote:
> 
> > We have a race condition between move_pages() and freeing hugepages,
> > where move_pages() calls follow_page(FOLL_GET) for hugepages internally
> > and tries to get its refcount without preventing concurrent freeing.
> > This race crashes the kernel, so this patch fixes it by moving FOLL_GET
> > code for hugepages into follow_huge_pmd() with taking the page table lock.
> > 
> 
> What about CONFIG_ARCH_WANT_GENERAL_HUGETLB=n configs?

Ah yes, I need cover them.
So I'll add some wrapper to do this locking in common hugetlb code.

Thanks,
Naoya Horiguchi
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