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Date: Fri, 2 Oct 2015 15:37:16 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: linux-mm@kvack.org, Jerome Marchand <jmarchan@redhat.com>,
        Hugh Dickins <hughd@google.com>, linux-kernel@vger.kernel.org,
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        Oleg Nesterov <oleg@redhat.com>, Linux API <linux-api@vger.kernel.org>,
        Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Subject: Re: [PATCH v4 3/4] mm, shmem: Add shmem resident memory accounting
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On Fri,  2 Oct 2015 15:35:50 +0200 Vlastimil Babka <vbabka@suse.cz> wrote:

> From: Jerome Marchand <jmarchan@redhat.com>

Changelog is a bit weird.

> Currently looking at /proc/<pid>/status or statm, there is no way to
> distinguish shmem pages from pages mapped to a regular file (shmem
> pages are mapped to /dev/zero), even though their implication in
> actual memory use is quite different.

OK, that's a bunch of stuff about the user interface.

> This patch adds MM_SHMEMPAGES counter to mm_rss_stat to account for
> shmem pages instead of MM_FILEPAGES.

And that has nothing to do with the user interface.

So now this little reader is all confused.  The patch doesn't actually
address the described problem at all, does it?  It's preparatory stuff
only?  No changes to the kernel's user interface?