Date: Wed, 5 Nov 2008 16:54:05 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Hugh Dickins <hugh@veritas.com>
Cc: "Eugene V. Lyubimkin" <jackyf.devel@gmail.com>,
       Peter Zijlstra <peterz@infradead.org>,
       Chris Friesen <cfriesen@nortel.com>, Rik van Riel <riel@redhat.com>,
       linux-kernel@vger.kernel.org, linux-mm <linux-mm@kvack.org>
Subject: Re: mmap: is default non-populating behavior stable?
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> (Every year or so we do wonder whether to change an extending mremap
> of a MAP_SHARED|MAP_ANONYMOUS object to extend the object itself instead
> of just SIGBUSing on the extension: but I've so far remained conservative
> about that, and Eugene appears to be thinking of more ordinary files.)

Try an mremap of a VM_GROWS* mapping and all the other things of this
nature. I would say our current behaviour is not what might be expected
by users. The extending an object case is just one example of weird
behaviour.

Alan


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