Re: [patch 2/3] MAP_NOZERO - implement sys_brk2()

From: Rik van Riel
Date: Tue Jun 26 2007 - 23:07:32 EST


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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