From 5528f9132cf65d4d892bcbc5684c61e7822b21e9 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 13 Aug 2010 09:24:04 -0700
Subject: mm: fix missing page table unmap for stack guard page failure case

From: Linus Torvalds <torvalds@linux-foundation.org>

commit 5528f9132cf65d4d892bcbc5684c61e7822b21e9 upstream.

.. which didn't show up in my tests because it's a no-op on x86-64 and
most other architectures.  But we enter the function with the last-level
page table mapped, and should unmap it at exit.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 mm/memory.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2783,8 +2783,10 @@ static int do_anonymous_page(struct mm_s
 	spinlock_t *ptl;
 	pte_t entry;
 
-	if (check_stack_guard_page(vma, address) < 0)
+	if (check_stack_guard_page(vma, address) < 0) {
+		pte_unmap(page_table);
 		return VM_FAULT_SIGBUS;
+	}
 
 	if (!(flags & FAULT_FLAG_WRITE)) {
 		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),