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Date: Tue, 28 Jan 2014 15:02:49 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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Subject: Re: [RFC] shmgetfd idea
References: <52E709C0.1050006@linaro.org> <52E7298D.5020001@zytor.com> <52E80B85.8020302@linaro.org> <52E814FF.6060403@zytor.com> <52E819F0.6040806@linaro.org> <CAPXgP11Fv6TU+o2Eui5rVW0A37U7KjwC0DZYbQOJJ8rEAYOiJg@mail.gmail.com> <52E81BB3.6060306@linaro.org> <52E81CE2.3030304@zytor.com> <52E8271B.4030201@linaro.org> <CAPXgP13G14B3YFpaE+m_AtFfFR6NRVSi1JYAvLZSsfftSkgwBQ@mail.gmail.com>
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To: Kay Sievers <kay@vrfy.org>, John Stultz <john.stultz@linaro.org>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>, Greg KH <gregkh@linuxfoundation.org>, Android Kernel Team <kernel-team@android.com>, Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mgorman@suse.de>, Hugh Dickins <hughd@google.com>, Dave Hansen <dave.hansen@intel.com>, Rik van Riel <riel@redhat.com>, Michel Lespinasse <walken@google.com>, Johannes Weiner <hannes@cmpxchg.org>, Neil Brown <neilb@suse.de>, Andrea Arcangeli <aarcange@redhat.com>, Takahiro Akashi <takahiro.akashi@linaro.org>, Minchan Kim <minchan@kernel.org>, Lennart Poettering <mzxreary@0pointer.de>

On 01/28/2014 02:14 PM, Kay Sievers wrote:
>>
>> But yes, alternatively classic systems may be able to get around the
>> issues via tmpfs quotas and convincing applications to use O_TMPFILE
>> there. But to me this seems less ideal then the Android approach, where
>> the lifecycle of the tmpfs fds more limited and clear.
> 
> Tmpfs supports no quota, it's all a huge hole and unsafe in that
> regard on every system today. But ashmem and kdbus, as they are today,
> are not better.
> 

We can fix that aspect in tmpfs.  Creating new file objcts outside of
filesystems really doesn't make things any better, since our toolbox
around this stuff largely revolves around filesystems.

	-hpa

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