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Date: Thu, 30 Apr 2015 00:37:44 +0300
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>,
        Mark Williamson <mwilliamson@undo-software.com>,
        Mark Seaborn <mseaborn@chromium.org>,
        kernel list <linux-kernel@vger.kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
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        Finn Grimwood <fgrimwood@undo-software.com>,
        Daniel James <djames@undo-software.com>,
        Cyrill Gorcunov <gorcunov@openvz.org>
Subject: Re: Regression: Requiring CAP_SYS_ADMIN for /proc/<pid>/pagemap
 causes application-level breakage
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On Wed, Apr 29, 2015 at 02:18:49PM -0700, Linus Torvalds wrote:
> On Wed, Apr 29, 2015 at 2:05 PM, Kirill A. Shutemov
> <kirill@shutemov.name> wrote:
> >
> > This sounds too ugly to be exposed it as ABI.
> 
> Oh, pretty it ain't. However, regressions in many ways are worse. If
> it makes it possible to not regress...

One idea is to extend kcmp(2) with KCMP_PAGE. idx1 and idx2 are virtual
addresses in two processes. It returns 0 if addresses points to the same
page and 3 otherwise.

Would it be enough for the use case?

I guess it could be too slow to check one page a time...

Invent new kcmpv(2)? ;)

-- 
 Kirill A. Shutemov
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