x86: fix page_is_ram() thinko

page_is_ram() has a special case for the 640k-1M bios area, however
due to a thinko the special case checks the e820 table entry and
not the memory the user has asked for. This patch fixes the bug.

[ mingo@elte.hu: this too is better solved in the e820 space, but those
  fixes are too intrusive for v2.6.25. ]

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>

1 files changed, 7 insertions, 8 deletions

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 7fb6eff644b3..f4c95aec5acb 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -50,6 +50,13 @@ int page_is_ram(unsigned long pagenr)
         if (pagenr == 0)
                 return 0;
 
+        /*
+         * Second special case: Some BIOSen report the PC BIOS
+         * area (640->1Mb) as ram even though it is not.
+         */
+        if (pagenr >= (BIOS_BEGIN >> PAGE_SHIFT) &&
+                    pagenr < (BIOS_END >> PAGE_SHIFT))
+                return 0;
 
         for (i = 0; i < e820.nr_map; i++) {
                 /*
@@ -60,14 +67,6 @@ int page_is_ram(unsigned long pagenr)
                 addr = (e820.map[i].addr + PAGE_SIZE-1) >> PAGE_SHIFT;
                 end = (e820.map[i].addr + e820.map[i].size) >> PAGE_SHIFT;
 
-                /*
-                 * Sanity check: Some BIOSen report areas as RAM that
-                 * are not. Notably the 640->1Mb area, which is the
-                 * PCI BIOS area.
-                 */
-                if (addr >= (BIOS_BEGIN >> PAGE_SHIFT) &&
-                    end < (BIOS_END >> PAGE_SHIFT))
-                        continue;
 
                 if ((pagenr >= addr) && (pagenr < end))
                         return 1;