From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: "David S. Miller" <davem@davemloft.net>
Cc: hugh@veritas.com, akpm@osdl.org, nickpiggin@yahoo.com.au,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 07/11] unpaged: COW on VM_UNPAGED
Date: Fri, 18 Nov 2005 19:12:10 +0000 [thread overview]
Message-ID: <1132341130.25914.73.camel@localhost.localdomain> (raw)
In-Reply-To: <20051117.155230.25121238.davem@davemloft.net>
On Iau, 2005-11-17 at 15:52 -0800, David S. Miller wrote:
> The cases I've seen, and am aware of, I documented in a previous
> mail and those involve MAP_PRIVATE maps of /dev/mem or other
> similar fixed page mapping devices.
>
> Which case truly needs COW faults on VM_RESERVED memory which
> isn't an application bug of some sort?
lrmi, X, vbetool, ...
In general these applications want to operate with a copy of the real
bios data mapped into the system. It might be possible to read some of
the data objects (eg the 0x400 page) but it is not possible to read the
BIOS ROM area as it may contain paged segments.
I suspect a read only bios map and an r/w read copy of the bios config
pages might work but the new behaviour is a serious regression breaking
legitimate code so it is problematic when it occurs without a years
warning in the middle of a fairly stable sequence of kernels.
next prev parent reply other threads:[~2005-11-18 18:40 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-17 19:28 [PATCH 00/11] unpaged: PageReserved VM fixups Hugh Dickins
2005-11-17 19:29 ` [PATCH 01/11] unpaged: get_user_pages VM_RESERVED Hugh Dickins
2005-11-17 23:29 ` David S. Miller
2005-11-17 19:30 ` [PATCH 02/11] unpaged: private write VM_RESERVED Hugh Dickins
2005-11-17 19:41 ` Dave Jones
2005-11-17 20:46 ` Dominik Brodowski
2005-11-17 20:51 ` Dave Jones
2005-11-17 23:58 ` David S. Miller
2005-11-18 7:12 ` Dominik Brodowski
2005-11-18 7:59 ` David S. Miller
2005-11-17 20:59 ` Dominik Brodowski
2005-11-17 23:36 ` David S. Miller
2005-11-17 19:31 ` [PATCH 03/11] unpaged: sound nopage get_page Hugh Dickins
2005-11-17 23:41 ` David S. Miller
2005-11-17 19:32 ` [PATCH 04/11] unpaged: unifdefed PageCompound Hugh Dickins
2005-11-17 23:43 ` David S. Miller
2005-11-19 20:15 ` Hugh Dickins
2005-11-19 20:55 ` William Lee Irwin III
2005-11-19 21:41 ` David S. Miller
2005-11-19 21:58 ` William Lee Irwin III
2005-11-17 19:34 ` [PATCH 05/11] unpaged: VM_UNPAGED Hugh Dickins
2005-11-17 20:59 ` William Lee Irwin III
2005-11-17 23:46 ` David S. Miller
2005-11-17 19:36 ` [PATCH 06/11] unpaged: VM_NONLINEAR VM_RESERVED Hugh Dickins
2005-11-17 19:37 ` [PATCH 07/11] unpaged: COW on VM_UNPAGED Hugh Dickins
2005-11-17 23:52 ` David S. Miller
2005-11-18 5:46 ` Nick Piggin
2005-11-18 6:45 ` David S. Miller
2005-11-18 7:27 ` Hugh Dickins
2005-11-18 7:46 ` Andrew Morton
2005-11-18 8:04 ` David S. Miller
2005-11-18 8:12 ` Hugh Dickins
2005-11-18 8:02 ` Hugh Dickins
2005-11-18 8:08 ` David S. Miller
2005-11-18 8:13 ` Hugh Dickins
2005-11-18 8:36 ` David S. Miller
2005-11-18 9:33 ` Hugh Dickins
2005-11-18 21:08 ` Dave Jones
2005-11-18 19:12 ` Alan Cox [this message]
2005-11-17 19:38 ` [PATCH 08/11] unpaged: anon in VM_UNPAGED Hugh Dickins
2005-11-17 19:38 ` [PATCH 09/11] unpaged: ZERO_PAGE " Hugh Dickins
2005-11-17 21:25 ` Ingo Oeser
2005-11-18 19:58 ` Hugh Dickins
2005-11-17 19:39 ` [PATCH 10/11] unpaged: PG_reserved bad_page Hugh Dickins
2005-11-17 19:40 ` [PATCH 11/11] unpaged: copy_page_range vma Hugh Dickins
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