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From: Florian Weimer <fweimer@redhat.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>,
	Nicholas Piggin <npiggin@gmail.com>
Cc: "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 12:26:12 +0100	[thread overview]
Message-ID: <c5586546-1e7e-0f0f-a8b3-680fadb38dcf@redhat.com> (raw)
In-Reply-To: <20171107111543.ep57evfxxbwwlhdh@node.shutemov.name>

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>

Thanks,
Florian

  reply	other threads:[~2017-11-07 11:26 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-03 17:05 POWER: Unexpected fault when writing to brk-allocated memory Florian Weimer
2017-11-05 12:18 ` Nicholas Piggin
2017-11-05 12:35   ` Florian Weimer
2017-11-05 12:54     ` Nicholas Piggin
2017-11-05 14:50   ` Florian Weimer
2017-11-06  6:18   ` Aneesh Kumar K.V
2017-11-06  6:47     ` Nicholas Piggin
2017-11-06  8:11       ` Florian Weimer
2017-11-06  8:25         ` Nicholas Piggin
2017-11-06  8:30           ` Aneesh Kumar K.V
2017-11-06  8:32             ` Florian Weimer
2017-11-06 10:20               ` Nicholas Piggin
2017-11-07  5:07               ` 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 [this message]
2017-11-07 11:44                     ` Kirill A. Shutemov
2017-11-07 13:05                       ` Florian Weimer
2017-11-07 13:16                         ` Kirill A. Shutemov
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
2017-11-10 12:08                                 ` David Laight
2017-11-11 10:30                                   ` Nicholas Piggin
2017-11-08  4:56                           ` Michael Ellerman
2017-11-08  8:30                             ` Kirill A. Shutemov
2017-11-06  8:10     ` Florian Weimer

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