linux-kernel - Re: [patch 2/3] MAP_NOZERO

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Message-ID: <4681D45F.7080309@redhat.com>
Date:	Tue, 26 Jun 2007 23:07:11 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Davide Libenzi <davidel@...ilserver.org>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [patch 2/3] MAP_NOZERO - implement sys_brk2()

Davide Libenzi wrote:
> The following patch implements the sys_brk2() syscall, that nothing is
> other than a sys_brk() with an extra "flags" parameter. This can be used
> to pass the new MAP_NOZERO bit, to ask the kernel to hand over non-zero
> pages if possible.

Since programs can get back free()d memory after a malloc(),
with the old contents of the memory intact, surely your
MAP_NONZERO behavior could be the default for programs that
can get away with it?

Maybe we could use some magic ELF header, similar to the
way non-executable stack is handled?

-- 
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