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From: John Hubbard <jhubbard@nvidia.com>
To: Kees Cook <keescook@chromium.org>,
	Michal Hocko <mhocko@kernel.org>,
	Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Linux API <linux-api@vger.kernel.org>,
	Khalid Aziz <khalid.aziz@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Russell King - ARM Linux <linux@armlinux.org.uk>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	Florian Weimer <fweimer@redhat.com>,
	Abdul Haleem <abdhalee@linux.vnet.ibm.com>,
	Joel Stanley <joel@jms.id.au>,
	Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH 0/2] mm: introduce MAP_FIXED_SAFE
Date: Wed, 6 Dec 2017 17:08:19 -0800
Message-ID: <c427dc00-2835-a475-1ef5-f5550c4113a0@nvidia.com> (raw)
In-Reply-To: <CAGXu5jKGsAjwF7nE_vjaWPnG0QJRx_qFeiSBLRg_g73iUJ-pwA@mail.gmail.com>

On 12/06/2017 04:19 PM, Kees Cook wrote:
> On Wed, Dec 6, 2017 at 1:08 AM, Michal Hocko <mhocko@kernel.org> wrote:
>> On Wed 06-12-17 08:33:37, Rasmus Villemoes wrote:
>>> On 2017-12-06 05:50, Michael Ellerman wrote:
>>>> Michal Hocko <mhocko@kernel.org> writes:
>>>>
>>>>> On Wed 29-11-17 14:25:36, Kees Cook wrote:
>>>>> It is safe in a sense it doesn't perform any address space dangerous
>>>>> operations. mmap is _inherently_ about the address space so the context
>>>>> should be kind of clear.
>>>>
>>>> So now you have to define what "dangerous" means.
>>>>
>>>>>> MAP_FIXED_UNIQUE
>>>>>> MAP_FIXED_ONCE
>>>>>> MAP_FIXED_FRESH
>>>>>
>>>>> Well, I can open a poll for the best name, but none of those you are
>>>>> proposing sound much better to me. Yeah, naming sucks...
>>>
>>> I also don't like the _SAFE name - MAP_FIXED in itself isn't unsafe [1],
>>> but I do agree that having a way to avoid clobbering (parts of) an
>>> existing mapping is quite useful. Since we're bikeshedding names, how
>>> about MAP_FIXED_EXCL, in analogy with the O_ flag.
>>
>> I really give up on the name discussion. I will take whatever the
>> majority comes up with. I just do not want this (useful) funtionality
>> get bikeched to death.
> 
> Yup, I really want this to land too. What do people think of Matthew
> Wilcox's MAP_REQUIRED ? MAP_EXACT isn't exact, and dropping "FIXED"
> out of the middle seems sensible to me.

+1, MAP_REQUIRED does sound like the best one so far, yes. Sorry if I contributed
to any excessive bikeshedding. :)

thanks,
john h

> 
> MIchael, any suggestions with your API hat on?
> 
> -Kees
> 

      reply index

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-29 14:42 Michal Hocko
2017-11-29 14:42 ` [PATCH 1/2] " Michal Hocko
2017-12-06  5:15   ` Michael Ellerman
2017-12-06  9:27     ` Michal Hocko
2017-12-06 10:02       ` Michal Hocko
2017-12-07 12:07   ` Pavel Machek
2017-11-29 14:42 ` [PATCH 2/2] fs, elf: drop MAP_FIXED usage from elf_map Michal Hocko
2017-11-29 17:45   ` Khalid Aziz
2017-11-29 14:45 ` [PATCH] mmap.2: document new MAP_FIXED_SAFE flag Michal Hocko
2017-11-30  3:16   ` John Hubbard
2017-11-30  8:23     ` Michal Hocko
2017-11-30  8:24   ` [PATCH v2] " Michal Hocko
2017-11-30 18:31     ` John Hubbard
2017-11-30 18:39       ` Michal Hocko
2017-11-29 15:13 ` [PATCH 0/2] mm: introduce MAP_FIXED_SAFE Rasmus Villemoes
     [not found]   ` <b154b794-7a8b-995e-0954-9234b9446b31-rjjw5hvvQKZaa/9Udqfwiw@public.gmane.org>
2017-11-29 15:50     ` Michal Hocko
2017-11-29 22:15   ` Kees Cook
2017-11-29 22:12 ` Kees Cook
2017-11-29 22:25 ` Kees Cook
     [not found]   ` <CAGXu5jLa=b2HhjWXXTQunaZuz11qUhm5aNXHpS26jVqb=G-gfw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-11-30  6:58     ` Michal Hocko
2017-12-01 15:26       ` Cyril Hrubis
2017-12-06  4:51         ` Michael Ellerman
2017-12-06  4:54           ` Matthew Wilcox
2017-12-06  7:03             ` Matthew Wilcox
2017-12-06  7:33               ` John Hubbard
     [not found]                 ` <5f4fc834-274a-b8f1-bda0-5bcddc5902ed-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2017-12-06  7:35                   ` Florian Weimer
2017-12-06  8:06                     ` John Hubbard
     [not found]                       ` <27ee1755-76d8-f086-5760-9c973b31108a-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2017-12-06  8:54                         ` Florian Weimer
     [not found]               ` <20171206070355.GA32044-PfSpb0PWhxZc2C7mugBRk2EX/6BAtgUQ@public.gmane.org>
2017-12-07  5:46                 ` Michael Ellerman
2017-12-07 19:14                   ` Kees Cook
     [not found]                     ` <CAGXu5jLWRQn6EaXEEvdvXr+4gbiJawwp1EaLMfYisHVfMiqgSA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-12-07 19:57                       ` Matthew Wilcox
2017-12-08  8:33                         ` Michal Hocko
     [not found]                           ` <20171208083315.GR20234-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2017-12-08 20:13                             ` Kees Cook
     [not found]                               ` <CAGXu5j+VupGmKEEHx-uNXw27Xvndu=0ObsBqMwQiaYPyMGD+vw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-12-08 20:57                                 ` Matthew Wilcox
2017-12-08 11:08                         ` Michael Ellerman
2017-12-08 14:27                           ` Pavel Machek
2017-12-08 20:31                             ` Cyril Hrubis
2017-12-08 20:47                             ` Florian Weimer
2017-12-08 14:33                           ` David Laight
2017-12-06  4:50       ` Michael Ellerman
     [not found]         ` <87zi6we9z2.fsf-W0DJWXSxmBNbyGPkN3NxC2scP1bn1w/D@public.gmane.org>
2017-12-06  7:33           ` Rasmus Villemoes
     [not found]             ` <a3b3129a-2626-a65e-59b0-68aada523723-rjjw5hvvQKZaa/9Udqfwiw@public.gmane.org>
2017-12-06  9:08               ` Michal Hocko
2017-12-07  0:19                 ` Kees Cook
2017-12-07  1:08                   ` John Hubbard [this message]

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