Re: [PATCHv4 08/25] thp: support file pages in zap_huge_pmd()

On Fri, Mar 18, 2016 at 07:23:41PM +0530, Aneesh Kumar K.V wrote:

"Kirill A. Shutemov" [off-list ref] writes:

quoted

[ text/plain ]
split_huge_pmd() for file mappings (and DAX too) is implemented by just
clearing pmd entry as we can re-fill this area from page cache on pte
level later.

This means we don't need deposit page tables when file THP is mapped.
Therefore we shouldn't try to withdraw a page table on zap_huge_pmd()
file THP PMD.

Archs like ppc64 use deposited page table to track the hardware page
table slot information. We probably may want to add hooks which arch can
use to achieve the same even with file THP 

Could you describe more on what kind of information you're talking about?

-- 
 Kirill A. Shutemov

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