Re: [PATCH v2 1/3] pagemap: add mmap-exclusive bit for marking pages mapped only here

[Kirill A. Shutemov]

On Tue, May 12, 2015 at 12:43:03PM +0300, Konstantin Khlebnikov wrote:
> This patch sets bit 56 in pagemap if this page is mapped only once.
> It allows to detect exclusively used pages without exposing PFN:
> 
> present file exclusive state
> 0       0    0         non-present
> 1       1    0         file page mapped somewhere else
> 1       1    1         file page mapped only here
> 1       0    0         anon non-CoWed page (shared with parent/child)
> 1       0    1         anon CoWed page (or never forked)

Probably, worth noting that file-private pages are anon in this context.

-- 
 Kirill A. Shutemov
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