linux-kernel - Re: [PATCH] mm: optionally disable brk()

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Message-ID: <f0947a6e-8110-99bb-4fb3-f730aaaa4b72@gmail.com>
Date:   Mon, 5 Oct 2020 19:14:15 +0300
From:   Topi Miettinen <toiwoton@...il.com>
To:     Jonathan Corbet <corbet@....net>
Cc:     Michal Hocko <mhocko@...e.com>,
        David Hildenbrand <david@...hat.com>,
        akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: optionally disable brk()

On 5.10.2020 17.12, Jonathan Corbet wrote:
> On Mon, 5 Oct 2020 11:11:35 +0300
> Topi Miettinen <toiwoton@...il.com> wrote:
> 
>> The point is not to shrink the kernel (it will shrink by one small
>> function) or get rid of complexity. The point is to disable an inferior
>> interface. Memory returned by mmap() is at a random location but with
>> brk() it is located near the data segment, so the address is more easily
>> predictable.
> 
> So if your true objective is to get glibc to allocate memory differently,
> perhaps the right thing to do is to patch glibc?

Of course:
https://sourceware.org/pipermail/libc-alpha/2020-October/118319.html

But since glibc is pretty much the only user of brk(), it also makes 
sense to disable it in the kernel if nothing uses it anymore.

-Topi