From: Roland Dreier <rdreier@cisco.com>
To: Linus Torvalds <torvalds@osdl.org>
Cc: "Michael S. Tsirkin" <mst@mellanox.co.il>,
Nick Piggin <nickpiggin@yahoo.com.au>,
Gleb Natapov <gleb@minantech.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
openib-general@openib.org, Petr Vandrovec <vandrove@vc.cvut.cz>,
Badari Pulavarty <pbadari@us.ibm.com>,
Hugh Dickins <hugh@veritas.com>
Subject: Re: [openib-general] Re: madvise MADV_DONTFORK/MADV_DOFORK
Date: Mon, 13 Feb 2006 11:16:32 -0800 [thread overview]
Message-ID: <adar767133j.fsf@cisco.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0602131104460.3691@g5.osdl.org> (Linus Torvalds's message of "Mon, 13 Feb 2006 11:05:37 -0800 (PST)")
Linus> Why?
Linus> That VM_DONTCOPY _is_ DONTFORK.
Linus> Don't add a new useless DONTFORK that doesn't have any
Linus> value.
VM_DONTCOPY is hardly used in the kernel, so the semantics aren't very
precisely defined. But the idea is that a driver setting VM_DONTCOPY
probably has a good reason for doing it, and we don't want userspace
to be able to erase that flag through madvise().
As Hugh said in his suggestion for a better changelog entry:
> Explain that MADV_DONTFORK should be reversible, hence
> MADV_DOFORK; but should not be reversible on areas a driver has
> so marked, hence VM_DONTFORK distinct from VM_DONTCOPY.
Perhaps we don't care for now, and we should wait and add
VM_KERNEL_DONTCOPY later if we really need it. I honestly don't know.
- Roland
next prev parent reply other threads:[~2006-02-13 19:16 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-13 15:41 madvise MADV_DONTFORK/MADV_DOFORK Michael S. Tsirkin
2006-02-13 18:23 ` Hugh Dickins
2006-02-13 19:02 ` Michael S. Tsirkin
2006-02-14 6:51 ` Gleb Natapov
2006-02-13 19:04 ` [openib-general] " Roland Dreier
2006-02-13 19:05 ` Linus Torvalds
2006-02-13 19:16 ` Roland Dreier [this message]
2006-02-13 19:34 ` [openib-general] " Linus Torvalds
2006-02-13 19:50 ` Hugh Dickins
2006-02-13 21:09 ` Michael S. Tsirkin
2006-02-13 21:57 ` Hugh Dickins
2006-02-13 22:09 ` Michael S. Tsirkin
2006-02-13 22:54 ` Hugh Dickins
2006-02-13 23:01 ` [PATCH] " Michael S. Tsirkin
2006-02-13 23:44 ` Hugh Dickins
2006-02-13 22:27 ` [openib-general] " Linus Torvalds
2006-02-13 22:55 ` Michael S. Tsirkin
2006-02-13 23:01 ` Hugh Dickins
2006-02-13 23:35 ` [PATCH] " Michael S. Tsirkin
2006-02-15 4:31 ` Nick Piggin
2006-02-15 6:09 ` Roland Dreier
2006-02-15 6:16 ` Andrew Morton
2006-02-15 6:34 ` [PATCH] Fix up MADV_DONTFORK/MADV_DOFORK definitions Roland Dreier
2006-02-15 6:48 ` Gleb Natapov
2006-02-15 7:06 ` Nick Piggin
2006-02-15 7:31 ` Bernd Eckenfels
2006-02-15 8:18 ` Michael S. Tsirkin
2006-02-15 8:13 ` [PATCH] madvise MADV_DONTFORK/MADV_DOFORK Michael S. Tsirkin
2006-02-13 20:05 ` Michael S. Tsirkin
2006-02-13 19:20 ` Michael S. Tsirkin
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