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Date: Sat, 21 Apr 2007 09:32:15 -0700
From: "Ulrich Drepper" <drepper@gmail.com>
To: "Hugh Dickins" <hugh@veritas.com>
Subject: Re: [PATCH] lazy freeing of memory through MADV_FREE 2/2
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
       "Rik van Riel" <riel@redhat.com>, "Jakub Jelinek" <jakub@redhat.com>,
       linux-kernel <linux-kernel@vger.kernel.org>,
       linux-mm <linux-mm@kvack.org>
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On 4/21/07, Hugh Dickins <hugh@veritas.com> wrote:
> But the Linux MADV_DONTNEED does throw away
> data from a PROT_WRITE,MAP_PRIVATE mapping (or brk or stack) - those
> changes are discarded, and a subsequent access will revert to zeroes
> or the underlying mapped file.  Been like that since before 2.4.0.

I didn't say it changed.  I just say that there is a hole in the
current implementation as it does not allow to implement
POSIX_MADV_DONTNEED with anything but a no-op.  The
POSIX_MADV_DONTNEED behavior is useful and something IMO should be
added to allow implementing it.