x86: fix WARN_ON() message: teach page_is_ram() about the special 4Kb bios data page
This patch teaches page_is_ram() about the fact that the first
4Kb of memory are special on x86, even though the E820 table
normally doesn't exclude it.
This fixes the WARN_ON() reported by Laurent Riffard who was also
very helpful in diagnosing the issue.
[ mingo@elte.hu: we are working on doing this properly in the e820
space, but for 2.6.25 this is the better fix. ]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 9f42d7e..7fb6eff 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -42,6 +42,15 @@
unsigned long addr, end;
int i;
+ /*
+ * A special case is the first 4Kb of memory;
+ * This is a BIOS owned area, not kernel ram, but generally
+ * not listed as such in the E820 table.
+ */
+ if (pagenr == 0)
+ return 0;
+
+
for (i = 0; i < e820.nr_map; i++) {
/*
* Not usable memory: