From: Michael Ellerman <mpe@ellerman.id.au>
To: Michal Hocko <mhocko@kernel.org>, Joel Stanley <joel@jms.id.au>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
Andrew Morton <akpm@linux-foundation.org>,
Linux-Next Mailing List <linux-next@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Russell King <linux@armlinux.org.uk>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Abdul Haleem <abdhalee@linux.vnet.ibm.com>,
Ralf Baechle <ralf@linux-mips.org>,
"James E.J. Bottomley" <jejb@parisc-linux.org>,
Helge Deller <deller@gmx.de>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Rich Felker <dalias@libc.org>,
"David S. Miller" <davem@davemloft.net>,
Chris Zankel <chris@zankel.net>,
Max Filippov <jcmvbkbc@gmail.com>,
linux-arm-kernel@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org, linux-mips@linux-mips.org,
linux-parisc@vger.kernel.orglinux-
Subject: Re: linux-next: Tree for Nov 7
Date: Mon, 13 Nov 2017 22:34:50 +1100 [thread overview]
Message-ID: <87lgjawgx1.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20171113094203.aofz2e7kueitk55y@dhcp22.suse.cz>
Hi Michal,
Michal Hocko <mhocko@kernel.org> writes:
> On Mon 13-11-17 10:20:06, Michal Hocko wrote:
>> [Cc arm and ppc maintainers]
>
> Hmm, it turned out to be a problem on other architectures as well.
> CCing more maintainers. For your reference, we are talking about
> http://lkml.kernel.org/r/20171023082608.6167-1-mhocko@kernel.org
> which has broken architectures which do apply aligning on the mmap
> address hint without MAP_FIXED applied. See below my proposed way
> around this issue because I belive that the above patch is quite
> valuable on its own to be dropped for all archs.
I don't really like your solution sorry :) The fact that you've had to
patch seven arches seems like a red flag.
I think this is a generic problem with MAP_FIXED, which I've heard
userspace folks complain about in the past.
Currently MAP_FIXED does two things:
1. makes addr not a hint but the required address
2. blasts any existing mapping
You want 1) but not 2).
So the right solution IMHO would be to add a new mmap flag to request
that behaviour, ie. a fixed address but iff there is nothing already
mapped there.
I don't know the mm code well enough to know if that's hard for some
reason, but it *seems* like it should be doable.
cheers
next prev parent reply other threads:[~2017-11-13 11:34 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-07 5:22 linux-next: Tree for Nov 7 Stephen Rothwell
2017-11-07 22:22 ` Joel Stanley
2017-11-08 14:20 ` Michal Hocko
2017-11-10 12:30 ` Michal Hocko
2017-11-12 1:08 ` Joel Stanley
2017-11-13 9:20 ` Michal Hocko
2017-11-13 9:34 ` Russell King - ARM Linux
2017-11-13 9:42 ` Michal Hocko
2017-11-13 11:34 ` Michael Ellerman [this message]
2017-11-13 12:00 ` Michal Hocko
2017-11-13 15:16 ` Michal Hocko
2017-11-13 15:48 ` Russell King - ARM Linux
2017-11-13 15:59 ` Michal Hocko
2017-11-13 15:49 ` Michal Hocko
2017-11-13 16:06 ` Michal Hocko
2017-11-13 16:35 ` Khalid Aziz
2017-11-14 7:07 ` Michal Hocko
2017-11-14 9:18 ` Michael Ellerman
2017-11-14 9:29 ` Michal Hocko
2017-11-14 9:02 ` Michael Ellerman
2017-11-14 8:54 ` Michael Ellerman
2017-11-14 9:04 ` Michal Hocko
2017-11-14 14:52 ` Khalid Aziz
2017-11-13 14:11 ` Michal Hocko
2017-11-13 15:09 ` Russell King - ARM Linux
2017-11-13 15:31 ` Michal Hocko
2017-11-14 0:03 ` Andrew Morton
2017-11-14 0:36 ` Stephen Rothwell
-- strict thread matches above, loose matches on Subject: below --
2023-11-07 1:17 Stephen Rothwell
2022-11-07 3:44 Stephen Rothwell
2019-11-07 8:07 Stephen Rothwell
2018-11-07 3:16 Stephen Rothwell
2013-11-07 7:31 Stephen Rothwell
2012-11-07 5:15 Stephen Rothwell
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