From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1756480AbaCTIrz (ORCPT <rfc822;w@1wt.eu>);
	Thu, 20 Mar 2014 04:47:55 -0400
Received: from mail-lb0-f182.google.com ([209.85.217.182]:54682 "EHLO
	mail-lb0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1752354AbaCTIrw (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Thu, 20 Mar 2014 04:47:52 -0400
Date: Thu, 20 Mar 2014 12:47:48 +0400
From: Cyrill Gorcunov <gorcunov@gmail.com>
To: David Herrmann <dh.herrmann@gmail.com>,
        Pavel Emelyanov <xemul@parallels.com>
Cc: linux-kernel@vger.kernel.org, Hugh Dickins <hughd@google.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Matthew Wilcox <matthew@wil.cx>,
        Karol Lewandowski <k.lewandowsk@samsung.com>,
        Kay Sievers <kay@vrfy.org>, Daniel Mack <zonque@gmail.com>,
        Lennart Poettering <lennart@poettering.net>,
        Kristian =?iso-8859-1?Q?H=F8gsberg?= <krh@bitplanet.net>,
        john.stultz@linaro.org, Greg Kroah-Hartman <greg@kroah.com>,
        Tejun Heo <tj@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>,
        dri-devel@lists.freedesktop.org, linux-fsdevel@vger.kernel.org,
        linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Ryan Lortie <desrt@desrt.ca>,
        "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Subject: Re: [PATCH 3/6] shm: add memfd_create() syscall
Message-ID: <20140320084748.GK1728@moon>
References: <1395256011-2423-1-git-send-email-dh.herrmann@gmail.com>
 <1395256011-2423-4-git-send-email-dh.herrmann@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1395256011-2423-4-git-send-email-dh.herrmann@gmail.com>
User-Agent: Mutt/1.5.21 (2010-09-15)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, Mar 19, 2014 at 08:06:48PM +0100, David Herrmann wrote:
> memfd_create() is similar to mmap(MAP_ANON), but returns a file-descriptor
> that you can pass to mmap(). It explicitly allows sealing and
> avoids any connection to user-visible mount-points. Thus, it's not
> subject to quotas on mounted file-systems, but can be used like
> malloc()'ed memory, but with a file-descriptor to it.
> 
> memfd_create() does not create a front-FD, but instead returns the raw
> shmem file, so calls like ftruncate() can be used. Also calls like fstat()
> will return proper information and mark the file as regular file. Sealing
> is explicitly supported on memfds.
> 
> Compared to O_TMPFILE, it does not require a tmpfs mount-point and is not
> subject to quotas and alike.

If I'm not mistaken in something obvious, this looks similar to /proc/pid/map_files
feature, Pavel?