From: Michal Hocko <mhocko@suse.cz>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Michael Kerrisk <mtk.manpages@gmail.com>
Cc: linux-mm <linux-mm@kvack.org>, Cyril Hrubis <chrubis@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Michel Lespinasse <walken@google.com>,
Rik van Riel <riel@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>
Subject: [RFC PATCH] mmap.2: clarify MAP_LOCKED semantic (was: Re: Should mmap MAP_LOCKED fail if mm_poppulate fails?)
Date: Wed, 29 Apr 2015 13:38:18 +0200 [thread overview]
Message-ID: <20150429113818.GC16097@dhcp22.suse.cz> (raw)
In-Reply-To: <CA+55aFyajquhGhw59qNWKGK4dBV0TPmDD7-1XqPo7DZWvO_hPg@mail.gmail.com>
On Tue 28-04-15 11:38:35, Linus Torvalds wrote:
> On Tue, Apr 28, 2015 at 11:35 AM, Michal Hocko <mhocko@suse.cz> wrote:
> >
> > I am still not sure I see the problem here.
>
> Basically, I absolutely hate the notion of us doing something
> unsynchronized, when I can see us undoing a mmap that another thread
> is doing. It's wrong.
OK, I have checked the mmap(2) man page and there is no single mention
about multi-threaded usage. So even though I personally think that
user fault handlers which do mmap(MAP_FIXED) without synchronization
to parallel mmaps are broken by definition we cannot simply rule them
out and it is not the kernel job to make them broken even more or in a
subtly different way.
So here is an RFC for the man page patch. I am not very good in the
format but man doesn't complain about any formating issues.
---
next prev parent reply other threads:[~2015-04-29 11:38 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-14 9:50 Should mmap MAP_LOCKED fail if mm_poppulate fails? Michal Hocko
2015-04-28 12:11 ` Michal Hocko
2015-04-28 12:11 ` [RFC 1/3] mm: mmap make MAP_LOCKED really mlock semantic Michal Hocko
2015-04-28 23:10 ` Andrew Morton
2015-04-29 7:52 ` Michal Hocko
2015-04-28 12:11 ` [RFC 2/3] mm: allow munmap related functions to understand gfp_mask Michal Hocko
2015-04-28 12:11 ` [RFC 3/3] mm: introduce do_munmap_nofail Michal Hocko
2015-04-28 16:01 ` Should mmap MAP_LOCKED fail if mm_poppulate fails? Linus Torvalds
2015-04-28 16:43 ` Michal Hocko
2015-04-28 16:57 ` Linus Torvalds
2015-04-28 18:35 ` Michal Hocko
2015-04-28 18:38 ` Linus Torvalds
2015-04-28 20:36 ` Michal Hocko
2015-04-29 11:38 ` Michal Hocko [this message]
2015-04-30 0:28 ` [RFC PATCH] mmap.2: clarify MAP_LOCKED semantic (was: Re: Should mmap MAP_LOCKED fail if mm_poppulate fails?) David Rientjes
2015-04-30 14:52 ` Michal Hocko
2015-05-06 12:21 ` Michal Hocko
2015-04-28 20:21 ` Should mmap MAP_LOCKED fail if mm_poppulate fails? Michal Hocko
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