From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Florian Weimer <fweimer@redhat.com>
Cc: Nicholas Piggin <npiggin@gmail.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
linuxppc-dev@lists.ozlabs.org, linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@amacapital.net>,
Dave Hansen <dave.hansen@intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-arch@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: POWER: Unexpected fault when writing to brk-allocated memory
Date: Tue, 7 Nov 2017 16:16:16 +0300 [thread overview]
Message-ID: <20171107131616.342goolaujjsnjge@node.shutemov.name> (raw)
In-Reply-To: <7fc1641b-361c-2ee2-c510-f7c64d173bf8@redhat.com>
On Tue, Nov 07, 2017 at 02:05:42PM +0100, Florian Weimer wrote:
> On 11/07/2017 12:44 PM, Kirill A. Shutemov wrote:
> > On Tue, Nov 07, 2017 at 12:26:12PM +0100, Florian Weimer wrote:
> > > On 11/07/2017 12:15 PM, Kirill A. Shutemov wrote:
> > >
> > > > > First of all, using addr and MAP_FIXED to develop our heuristic can
> > > > > never really give unchanged ABI. It's an in-band signal. brk() is a
> > > > > good example that steadily keeps incrementing address, so depending
> > > > > on malloc usage and address space randomization, you will get a brk()
> > > > > that ends exactly at 128T, then the next one will be >
> > > > > DEFAULT_MAP_WINDOW, and it will switch you to 56 bit address space.
> > > >
> > > > No, it won't. You will hit stack first.
> > >
> > > That's not actually true on POWER in some cases. See the process maps I
> > > posted here:
> > >
> > > <https://marc.info/?l=linuxppc-embedded&m=150988538106263&w=2>
> >
> > Hm? I see that in all three cases the [stack] is the last mapping.
> > Do I miss something?
>
> Hah, I had not noticed. Occasionally, the order of heap and stack is
> reversed. This happens in approximately 15% of the runs.
Heh. I guess ASLR on Power is too fancy :)
That's strange layout. It doesn't give that much (relatively speaking)
virtual address space for both stack and heap to grow.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2017-11-07 13:16 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <f251fc3e-c657-ebe8-acc8-f55ab4caa667@redhat.com>
[not found] ` <20171105231850.5e313e46@roar.ozlabs.ibm.com>
[not found] ` <871slcszfl.fsf@linux.vnet.ibm.com>
[not found] ` <20171106174707.19f6c495@roar.ozlabs.ibm.com>
[not found] ` <24b93038-76f7-33df-d02e-facb0ce61cd2@redhat.com>
[not found] ` <20171106192524.12ea3187@roar.ozlabs.ibm.com>
[not found] ` <d52581f4-8ca4-5421-0862-3098031e29a8@linux.vnet.ibm.com>
[not found] ` <546d4155-5b7c-6dba-b642-29c103e336bc@redhat.com>
2017-11-07 5:07 ` POWER: Unexpected fault when writing to brk-allocated memory Nicholas Piggin
2017-11-07 8:15 ` Florian Weimer
2017-11-07 9:24 ` Nicholas Piggin
2017-11-07 11:16 ` Kirill A. Shutemov
2017-11-07 11:15 ` Kirill A. Shutemov
2017-11-07 11:26 ` Florian Weimer
2017-11-07 11:44 ` Kirill A. Shutemov
2017-11-07 13:05 ` Florian Weimer
2017-11-07 13:16 ` Kirill A. Shutemov [this message]
2017-11-08 6:08 ` Michael Ellerman
2017-11-08 6:18 ` Florian Weimer
2017-11-07 11:56 ` Nicholas Piggin
2017-11-07 12:28 ` Kirill A. Shutemov
2017-11-07 13:33 ` Nicholas Piggin
2017-11-07 13:45 ` Aneesh Kumar K.V
2017-11-07 14:01 ` Kirill A. Shutemov
2017-11-09 17:15 ` Nicholas Piggin
2017-11-09 19:44 ` Matthew Wilcox
2017-11-10 1:26 ` Nicholas Piggin
[not found] ` <063D6719AE5E284EB5DD2968C1650D6DD00B84EF@AcuExch.aculab.com>
2017-11-11 10:30 ` Nicholas Piggin
2017-11-08 4:56 ` Michael Ellerman
2017-11-08 8:30 ` Kirill A. Shutemov
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=20171107131616.342goolaujjsnjge@node.shutemov.name \
--to=kirill@shutemov.name \
--cc=akpm@linux-foundation.org \
--cc=aneesh.kumar@linux.vnet.ibm.com \
--cc=dave.hansen@intel.com \
--cc=fweimer@redhat.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=luto@amacapital.net \
--cc=mingo@kernel.org \
--cc=npiggin@gmail.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
/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).