linux-kernel - [PATCH] fb-defio: Inhibit setting VM_IO flag if FBINFO

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Date:	Thu,  3 Dec 2009 10:31:55 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	jayakumar.lkml@...il.com, damm@...nsource.se,
	linux-kernel@...r.kernel.org
Cc:	armbru@...hat.com, jeremy@...p.org
Subject: [PATCH] fb-defio: Inhibit setting VM_IO flag if FBINFO_VIRTFB is set.

Hey Jaya and Magnus,

I was wondering if I could get your opinion and hopefully an ACK on these
following patches?  They fix an issue when Linux is running in a Xen paravirt
environment with the framebuffer enabled. This bug looks to have been in
existence for a long time and finally has been tracked down.

Essentially the VM_IO flag, that is set in fb_deferred_io_mmap, has a special
meaning for Xen-paravirt Linux. It is used to signify pages that are backed by
PCI devices memory (BARs, and such). Having other types of memory (System RAM)
marked with this flag, throws a monkey wrench in the accounting and we end
up with infinite General Protection Fault occurring during boot-up.

The first two patches fix the problem. The last one is a cleanup of the
other users of fb_deferred that use a framebuffer allocated from System RAM.

Thank you for taking the time to review these patches.

Sincerely,

Konrad Rzeszutek Wilk
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