From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Michal Hocko <mhocko@kernel.org>
Cc: Joel Stanley <joel@jms.id.au>,
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>,
linux-arm-kernel@lists.infradead.org,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Abdul Haleem <abdhalee@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: linux-next: Tree for Nov 7
Date: Mon, 13 Nov 2017 09:34:23 +0000 [thread overview]
Message-ID: <20171113093423.GI12318@n2100.armlinux.org.uk> (raw)
In-Reply-To: <20171113092006.cjw2njjukt6limvb@dhcp22.suse.cz>
On Mon, Nov 13, 2017 at 10:20:06AM +0100, Michal Hocko wrote:
> [Cc arm and ppc maintainers]
>
> Thanks a lot for testing!
>
> On Sun 12-11-17 11:38:02, Joel Stanley wrote:
> > On Fri, Nov 10, 2017 at 11:00 PM, Michal Hocko <mhocko@kernel.org> wrote:
> > > Hi Joel,
> > >
> > > On Wed 08-11-17 15:20:50, Michal Hocko wrote:
> > > [...]
> > >> > There are a lot of messages on the way up that look like this:
> > >> >
> > >> > [ 2.527460] Uhuuh, elf segement at 000d9000 requested but the
> > >> > memory is mapped already
> > >> > [ 2.540160] Uhuuh, elf segement at 000d9000 requested but the
> > >> > memory is mapped already
> > >> > [ 2.546153] Uhuuh, elf segement at 000d9000 requested but the
> > >> > memory is mapped already
> > >> >
> > >> > And then trying to run userspace looks like this:
> > >>
> > >> Could you please run with debugging patch posted
> > >> http://lkml.kernel.org/r/20171107102854.vylrtaodla63kc57@dhcp22.suse.cz
> > >
> > > Did you have chance to test with this debugging patch, please?
> >
> > Lots of this:
> >
> > [ 1.177266] Uhuuh, elf segement at 000d9000 requested but the memory is mapped already, got 000dd000
> > [ 1.177555] Clashing vma [dd000, de000] flags:100873 name:(null)
>
> This smells like the problem I've expected that mmap with hint doesn't
> respect the hint even though there is no clashing mapping. The above
> basically says that we didn't map at 0xd9000 but it has placed it at
> 0xdd000. The nearest (clashing) vma is at 0xdd000 so this is our new
> mapping. find_vma returns the closest vma (with addr < vm_end) for the
> given address 0xd9000 so this address cannot be mapped by any other vma.
>
> Now that I am looking at arm's arch_get_unmapped_area it does perform
> aligning for shared vmas. We do not do that for MAP_FIXED. Powepc,
> reported earlier [1] seems to suffer from the similar problem.
> slice_get_unmapped_area alignes to slices, whatever that means.
>
> I can see two possible ways around that. Either we explicitly request
> non-aligned mappings via a special MAP_$FOO (e.g. MAP_FIXED_SAFE) or
> simply opt out from the MAP_FIXED protection via ifdefs. The first
> option sounds more generic to me but also more tricky to not introduce
> other user visible effects. The later is quite straightforward. What do
> you think about the following on top of the previous patch?
>
> It is rather terse and disables the MAP_FIXED protection for arm
> comletely because I couldn't find a way to make it conditional on
> CACHEID_VIPT_ALIASING. But this can be always handled later. I find the
> protection for other archtectures useful enough to have this working for
> most architectures now and handle others specially.
Can someone provide the background information for this please?
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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next prev parent reply other threads:[~2017-11-13 9:34 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 [this message]
2017-11-13 9:42 ` Michal Hocko
2017-11-13 11:34 ` Michael Ellerman
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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