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Date: Wed, 9 Jul 2014 01:51:59 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Christoph Hellwig <hch@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Konstantin Khlebnikov <koct9i@gmail.com>,
        Wu Fengguang <fengguang.wu@intel.com>,
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        Borislav Petkov <bp@alien8.de>,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
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        linux-mm@kvack.org, Dave Hansen <dave.hansen@intel.com>,
        Dave Chinner <david@fromorbit.com>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Linux API <linux-api@vger.kernel.org>,
        Naoya Horiguchi <nao.horiguchi@gmail.com>
Subject: Re: [PATCH v3 0/3] mm: introduce fincore() v3
Message-ID: <20140709085159.GA10693@infradead.org>
References: <1404756006-23794-1-git-send-email-n-horiguchi@ah.jp.nec.com>
 <20140708121618.GA2554@infradead.org>
 <20140708132755.GA24698@nhori>
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On Tue, Jul 08, 2014 at 09:27:55AM -0400, Naoya Horiguchi wrote:
> On Tue, Jul 08, 2014 at 05:16:18AM -0700, Christoph Hellwig wrote:
> > Still a hard NAK for exposing page flags in a syscall ABI.  These are
> > way to volatile to go into an application interface.
> 
> Is there any specific reason that exporting via syscall ABI is more
> volatile than exporting via procfs as /proc/kpageflags alreadly does?

An optional proc debug output is very different from an actual system
call.