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From: Johannes Weiner <hannes@cmpxchg.org>
To: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Tejun Heo <tj@kernel.org>, Hugh Dickins <hughd@google.com>,
	Michel Lespinasse <walken@google.com>,
	linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [patch 2/3] mm: memory: remove ->vm_file check on shared writable vmas
Date: Tue, 2 Dec 2014 10:18:29 -0500	[thread overview]
Message-ID: <20141202151829.GC8401@phnom.home.cmpxchg.org> (raw)
In-Reply-To: <20141202085825.GA9092@quack.suse.cz>

On Tue, Dec 02, 2014 at 09:58:25AM +0100, Jan Kara wrote:
> On Mon 01-12-14 17:58:01, Johannes Weiner wrote:
> > The only way a VMA can have shared and writable semantics is with a
> > backing file.
>   OK, one always learns :) After some digging I found that MAP_SHARED |
> MAP_ANONYMOUS mappings are in fact mappings of a temporary file in tmpfs.
> It would be worth to mention this in the changelog I believe. Otherwise
> feel free to add:
>   Reviewed-by: Jan Kara <jack@suse.cz>

Thanks, Jan.  I updated the changelog to read:

Shared anonymous mmaps are implemented with shmem files, so all VMAs
with shared writable semantics also have an underlying backing file.

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  reply	other threads:[~2014-12-02 15:18 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-01 22:58 [patch 1/3] mm: protect set_page_dirty() from ongoing truncation Johannes Weiner
2014-12-01 22:58 ` [patch 2/3] mm: memory: remove ->vm_file check on shared writable vmas Johannes Weiner
2014-12-02  8:58   ` Jan Kara
2014-12-02 15:18     ` Johannes Weiner [this message]
2014-12-02 12:00   ` Kirill A. Shutemov
2014-12-01 22:58 ` [patch 3/3] mm: memory: merge shared-writable dirtying branches in do_wp_page() Johannes Weiner
2014-12-02  9:19   ` Jan Kara
2014-12-02 16:56     ` Johannes Weiner
2014-12-02 12:08   ` Kirill A. Shutemov
2014-12-02  9:12 ` [patch 1/3] mm: protect set_page_dirty() from ongoing truncation Jan Kara
2014-12-02 15:06   ` Johannes Weiner
2014-12-02 11:56 ` Kirill A. Shutemov
2014-12-02 15:11   ` Johannes Weiner
  -- strict thread matches above, loose matches on Subject: below --
2014-12-05 14:52 Johannes Weiner
2014-12-05 14:52 ` [patch 2/3] mm: memory: remove ->vm_file check on shared writable vmas Johannes Weiner
2014-12-16 16:18 [patch 0/3 resend] mm: close race between dirtying and truncation Johannes Weiner
2014-12-16 16:18 ` [patch 2/3] mm: memory: remove ->vm_file check on shared writable vmas Johannes Weiner

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