[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>

diff --git a/include/asm-x86_64/processor.h b/include/asm-x86_64/processor.h
index f0581c35628e8fa2abf8385c514824c015c4a652..9f74a286ef1112be8e15cc78d92b8269d0dfa852 100644 (file)
--- a/include/asm-x86_64/processor.h
+++ b/include/asm-x86_64/processor.h
@@ -159,9 +159,9 @@ 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.