From mboxrd@z Thu Jan  1 00:00:00 1970
From: Matthew Wilcox <matthew@wil.cx>
Subject: Re: Bugs on Linux 2.6.18-rc2 sg code?
Date: Sat, 19 Aug 2006 11:20:24 -0600
Message-ID: <20060819172024.GS4340@parisc-linux.org>
References: <8202f4270608101843r7df002d2l40e03eca3271b050@mail.gmail.com> <44E6388D.1000206@torque.net> <44E68F76.4010702@torque.net>
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To: Douglas Gilbert <dougg@torque.net>
Cc: Fajun Chen <fajunchen@gmail.com>, linux-scsi@vger.kernel.org, akpm@osdl.org

On Sat, Aug 19, 2006 at 12:11:34AM -0400, Douglas Gilbert wrote:
> > Your point about the change to sg_vma_nopage() between
> > lk 2.6.15 and lk 2.6.16 also seems to be correct.
> > The most indented part of that function has been
> > changed from incrementing the change count on the
> > reported page (as indicated by 'offset') in a
> > compound page allocation to ignoring the 'offset'
> > and incrementing the page count on the first page
> > in a compound page allocation.
>  		if (offset < len) {
> -			page = sg->page;
> +			page = virt_to_page(page_address(sg->page) + offset);
>  			get_page(page);	/* increment page count */

But page_address can return NULL on highmem machines.  Or are you
guaranteed that these are lowmem pages?