From: "David S. Miller" <davem@davemloft.net>
To: hugh@veritas.com
Cc: akpm@osdl.org, nickpiggin@yahoo.com.au, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 07/11] unpaged: COW on VM_UNPAGED
Date: Thu, 17 Nov 2005 15:52:30 -0800 (PST) [thread overview]
Message-ID: <20051117.155230.25121238.davem@davemloft.net> (raw)
In-Reply-To: <Pine.LNX.4.61.0511171936440.4563@goblin.wat.veritas.com>
From: Hugh Dickins <hugh@veritas.com>
Date: Thu, 17 Nov 2005 19:37:23 +0000 (GMT)
> Remove the BUG_ON(vma->vm_flags & VM_UNPAGED) from do_wp_page, and let
> it do Copy-On-Write without touching the VM_UNPAGED's page counts - but
> this is incomplete, because the anonymous page it inserts will itself
> need to be handled, here and in other functions - next patch.
>
> We still don't copy the page if the pfn is invalid, because the
> copy_user_highpage interface does not allow it. But that's not been
> a problem in the past: can be added in later if the need arises.
>
> Signed-off-by: Hugh Dickins <hugh@veritas.com>
Do we even need this? It is a very serious question...
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?
next prev parent reply other threads:[~2005-11-17 23:53 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 [this message]
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
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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