From d8a9e6a51ec58486f850e3606e3fcb86b5b7da41 Mon Sep 17 00:00:00 2001 From: Arjan van de Ven Date: Mon, 18 Feb 2008 09:54:33 -0800 Subject: 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 Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/mm/ioremap.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'arch/x86') diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 9f42d7e9c15..7fb6eff644b 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -42,6 +42,15 @@ int page_is_ram(unsigned long pagenr) 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: -- cgit v1.2.3