From: David Laight <David.Laight@ACULAB.COM>
To: 'David Hildenbrand' <david@redhat.com>,
Topi Miettinen <toiwoton@gmail.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] mm: optionally disable brk()
Date: Fri, 2 Oct 2020 21:19:33 +0000 [thread overview]
Message-ID: <a6d03b97f74543ef8203c53b2c028fef@AcuMS.aculab.com> (raw)
In-Reply-To: <653873ef-2a57-37e0-1ac3-fba763652b35@redhat.com>
From: David Hildenbrand
> Sent: 02 October 2020 18:52
>
> On 02.10.20 19:19, Topi Miettinen wrote:
> > The brk() system call allows to change data segment size (heap). This
> > is mainly used by glibc for memory allocation, but it can use mmap()
> > and that results in more randomized memory mappings since the heap is
> > always located at fixed offset to program while mmap()ed memory is
> > randomized.
>
> Want to take more Unix out of Linux?
>
> Honestly, why care about disabling? User space can happily use mmap() if
> it prefers.
I bet some obscure applications rely on it.
Although hopefully nothing still does heap allocation
by just increasing the VA and calling brk() in response
to SIGSEGV.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-10-02 21:19 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-02 17:19 [PATCH] mm: optionally disable brk() Topi Miettinen
2020-10-02 17:52 ` David Hildenbrand
2020-10-02 21:19 ` David Laight [this message]
2020-10-02 21:44 ` Topi Miettinen
2020-10-05 6:12 ` Michal Hocko
2020-10-05 8:11 ` Topi Miettinen
2020-10-05 8:22 ` Michal Hocko
2020-10-05 9:03 ` Topi Miettinen
2020-10-05 14:12 ` Jonathan Corbet
2020-10-05 16:14 ` Topi Miettinen
2020-10-05 9:13 ` David Hildenbrand
2020-10-05 9:20 ` Michal Hocko
2020-10-05 9:47 ` Topi Miettinen
2020-10-05 9:55 ` David Hildenbrand
2020-10-05 11:21 ` David Laight
2020-10-05 12:18 ` David Hildenbrand
2020-10-05 12:25 ` David Laight
2020-10-07 9:43 ` Topi Miettinen
2020-11-01 11:41 ` Topi Miettinen
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