From 38cb47ba0187c481aa949d3bbf149e014e8cacda Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 4 Feb 2008 16:47:54 +0100
Subject: [PATCH] x86: relax RAM check in ioremap()
Kevin Winchester reported the loss of direct rendering, due to:
[ 0.588184] agpgart: Detected AGP bridge 0
[ 0.588184] agpgart: unable to get memory for graphics translation table.
[ 0.588184] agpgart: agp_backend_initialize() failed.
[ 0.588207] agpgart-amd64: probe of 0000:00:00.0 failed with error -12
and bisected it down to:
commit 266b9f8727976769e2ed2dad77ac9295f37e321e
Author: Thomas Gleixner <tglx@linutronix.de>
Date: Wed Jan 30 13:34:06 2008 +0100
x86: fix ioremap RAM check
this check was too strict and caused an ioremap() failure.
the problem is due to the somewhat unclean way of how the GART code
reserves a memory range for its aperture, and how it utilizes it
later on.
Allow RAM pages to be ioremap()-ed too, as long as they are reserved.
Bisected-by: Kevin Winchester <kjwinchester@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Kevin Winchester <kjwinchester@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/mm/ioremap.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index c004d94608fd..1a88d1572a77 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -116,7 +116,7 @@ static void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
{
void __iomem *addr;
struct vm_struct *area;
- unsigned long offset, last_addr;
+ unsigned long pfn, offset, last_addr;
pgprot_t prot;
/* Don't allow wraparound or zero size */
@@ -133,9 +133,10 @@ static void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
/*
* Don't allow anybody to remap normal RAM that we're using..
*/
- for (offset = phys_addr >> PAGE_SHIFT; offset < max_pfn_mapped &&
- (offset << PAGE_SHIFT) < last_addr; offset++) {
- if (page_is_ram(offset))
+ for (pfn = phys_addr >> PAGE_SHIFT; pfn < max_pfn_mapped &&
+ (pfn << PAGE_SHIFT) < last_addr; pfn++) {
+ if (page_is_ram(pfn) && pfn_valid(pfn) &&
+ !PageReserved(pfn_to_page(pfn)))
return NULL;
}