[PATCH] x86_64: Add a guard page at the end of the 47bit address space

This works around a bug in the AMD K8 CPUs.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Chris Wright <chrisw@osdl.org>

diff --git a/include/asm-x86_64/processor.h b/include/asm-x86_64/processor.h
index 6dadc6400319797b6937fd0f7312fe9297f1b1ae..31e8d82ce00773fde72edca0e5cbabf2c733e70f 100644 (file)
--- a/include/asm-x86_64/processor.h
+++ b/include/asm-x86_64/processor.h
@@ -160,9 +160,9 @@ static inline void clear_in_cr4 (unsigned long mask)
 
 
 /*
- * User space process size. 47bits.
+ * User space process size. 47bits minus one guard page.
  */
-#define TASK_SIZE      (0x800000000000UL)
+#define TASK_SIZE      (0x800000000000UL - 4096)
 
 /* This decides where the kernel will search for a free chunk of vm
  * space during mmap's.