From: Michal Hocko <mhocko@kernel.org>
To: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
akpm@linux-foundation.org, mm-commits@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org, linux-next@vger.kernel.org,
sfr@canb.auug.org.au, broonie@kernel.org
Subject: Re: ppc elf_map breakage with MAP_FIXED_NOREPLACE
Date: Wed, 24 Jan 2018 10:05:39 +0100 [thread overview]
Message-ID: <20180124090539.GH1526@dhcp22.suse.cz> (raw)
In-Reply-To: <2a05eaf2-20fd-57a8-d4bd-5a1fbf57686c@linux.vnet.ibm.com>
On Wed 24-01-18 10:39:41, Anshuman Khandual wrote:
> On 01/23/2018 09:36 PM, Michal Hocko wrote:
> > On Tue 23-01-18 21:28:28, Anshuman Khandual wrote:
> >> On 01/23/2018 06:15 PM, Michal Hocko wrote:
> >>> On Tue 23-01-18 16:55:18, Anshuman Khandual wrote:
> >>>> On 01/17/2018 01:37 PM, Michal Hocko wrote:
> >>>>> On Thu 11-01-18 15:38:37, Anshuman Khandual wrote:
> >>>>>> On 01/09/2018 09:43 PM, Michal Hocko wrote:
> >>>>> [...]
> >>>>>>> Did you manage to catch _who_ is requesting that anonymous mapping? Do
> >>>>>>> you need a help with the debugging patch?
> >>>>>>
> >>>>>> Not yet, will get back on this.
> >>>>>
> >>>>> ping?
> >>>>
> >>>> Hey Michal,
> >>>>
> >>>> Missed this thread, my apologies. This problem is happening only with
> >>>> certain binaries like 'sed', 'tmux', 'hostname', 'pkg-config' etc. As
> >>>> you had mentioned before the map request collision is happening on
> >>>> [10030000, 10040000] and [10030000, 10040000] ranges only which is
> >>>> just a single PAGE_SIZE. You asked previously that who might have
> >>>> requested the anon mapping which is already present in there ? Would
> >>>> not that be the same process itself ? I am bit confused.
> >>>
> >>> We are early in the ELF loading. If we are mapping over an existing
> >>> mapping then we are effectivelly corrupting it. In other words exactly
> >>> what this patch tries to prevent. I fail to see what would be a relevant
> >>> anon mapping this early and why it would be colliding with elf
> >>> segements.
> >>>
> >>>> Would it be
> >>>> helpful to trap all the mmap() requests from any of the binaries
> >>>> and see where we might have created that anon mapping ?
> >>>
> >>> Yeah, that is exactly what I was suggesting. Sorry for not being clear
> >>> about that.
> >>>
> >>
> >> Tried to instrument just for the 'sed' binary and dont see any where
> >> it actually requests the anon VMA which got hit when loading the ELF
> >> section which is strange. All these requested flags here already has
> >> MAP_FIXED_NOREPLACE (0x100000). Wondering from where the anon VMA
> >> actually came from.
> >
> > Could you try to dump backtrace?
>
> This is when it fails inside elf_map() function due to collision with
> existing anon VMA mapping.
This is not the interesting one. This is the ELF loader. And we know it
fails. We are really interested in the one _who_ installs the original
VMA. Because nothing should be really there.
It would be also very helpful to translate the backtrace with faddr2line
to get line numbers.
> [c000201c9ad07880] [c000000000b0b4c0] dump_stack+0xb0/0xf0 (unreliable)
> [c000201c9ad078c0] [c0000000003c4550] elf_map+0x2d0/0x310
> [c000201c9ad07b60] [c0000000003c6258] load_elf_binary+0x6f8/0x158c
> [c000201c9ad07c80] [c000000000352900] search_binary_handler+0xd0/0x270
> [c000201c9ad07d10] [c000000000354838] do_execveat_common.isra.31+0x658/0x890
> [c000201c9ad07df0] [c000000000354e80] SyS_execve+0x40/0x50
> [c000201c9ad07e30] [c00000000000b220] system_call+0x58/0x6c
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-01-24 9:07 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-05 0:20 mmotm 2018-01-04-16-19 uploaded akpm
2018-01-05 6:43 ` Anshuman Khandual
2018-01-05 8:46 ` Michal Hocko
2018-01-07 6:49 ` Anshuman Khandual
2018-01-07 9:02 ` ppc elf_map breakage with MAP_FIXED_NOREPLACE (was: Re: mmotm 2018-01-04-16-19 uploaded) Michal Hocko
2018-01-07 11:26 ` Michael Ellerman
2018-01-08 3:02 ` ppc elf_map breakage with MAP_FIXED_NOREPLACE Anshuman Khandual
2018-01-08 22:12 ` Michael Ellerman
2018-01-09 11:48 ` Anshuman Khandual
2018-01-09 16:13 ` Michal Hocko
2018-01-11 10:08 ` Anshuman Khandual
2018-01-17 8:07 ` Michal Hocko
2018-01-23 11:25 ` Anshuman Khandual
2018-01-23 12:45 ` Michal Hocko
2018-01-23 15:58 ` Anshuman Khandual
2018-01-23 16:06 ` Michal Hocko
2018-01-24 5:09 ` Anshuman Khandual
2018-01-24 9:05 ` Michal Hocko [this message]
2018-01-26 12:34 ` Anshuman Khandual
2018-01-26 14:04 ` Michal Hocko
2018-01-29 2:47 ` Anshuman Khandual
2018-01-29 5:32 ` Anshuman Khandual
2018-01-29 13:22 ` Michal Hocko
[not found] ` <87k1w081e7.fsf@concordia.ellerman.id.au>
2018-01-30 9:42 ` Michal Hocko
2018-01-31 5:05 ` Anshuman Khandual
2018-01-31 13:19 ` Michal Hocko
2018-02-01 3:13 ` Anshuman Khandual
2018-02-01 13:10 ` Michal Hocko
2018-02-01 13:40 ` Michal Hocko
2018-02-01 20:55 ` Kees Cook
2018-02-13 10:04 ` [RFC PATCH] elf: enforce MAP_FIXED on overlaying elf segments (was: Re: ppc elf_map breakage with MAP_FIXED_NOREPLACE) Michal Hocko
2018-02-14 16:30 ` Khalid Aziz
2018-02-01 13:48 ` ppc elf_map breakage with MAP_FIXED_NOREPLACE Michal Hocko
2018-02-01 21:06 ` Kees Cook
2018-02-12 14:48 ` Michal Hocko
2018-02-13 1:02 ` Anshuman Khandual
2018-02-13 6:49 ` Anshuman Khandual
2018-02-13 10:00 ` Michal Hocko
2018-01-05 12:14 ` mmotm 2018-01-04-16-19 uploaded Michal Hocko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180124090539.GH1526@dhcp22.suse.cz \
--to=mhocko@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=broonie@kernel.org \
--cc=khandual@linux.vnet.ibm.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-next@vger.kernel.org \
--cc=mm-commits@vger.kernel.org \
--cc=mpe@ellerman.id.au \
--cc=sfr@canb.auug.org.au \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).