linux-kernel - Re: missing madvise functionality

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Message-ID: <p73648dz5oa.fsf@bingen.suse.de>
Date:	03 Apr 2007 20:14:29 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Ulrich Drepper <drepper@...hat.com>
Cc:	Rik van Riel <riel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Jakub Jelinek <jakub@...hat.com>
Subject: Re: missing madvise functionality

Ulrich Drepper <drepper@...hat.com> writes:

>   to free:      mmap(PROT_NONE) over the area

Why do you need a lock for that? I don't see any problem with
two threads doing that in parallel. The kernel would
serialize it internally and one would fail, but that shouldn't
be a problem. 

Of course having the lock should also not make much difference --
if glibc doesn't do it then it kernel would anyways and run
into the same scalability issue on mmap_sem.

-Andi

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