From: Hugh Dickins <hughd@google.com>
Date: Tue, 10 May 2011 00:44:42 +0000 (-0700)
Subject: vm: fix vm_pgoff wrap in upward expansion
X-Git-Tag: v2.6.32.47~9
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=dbb6e675314ddf4f1011a080e2fee0012134f83f;p=linux-pvops.git

vm: fix vm_pgoff wrap in upward expansion

commit 42c36f63ac1366ab0ecc2d5717821362c259f517 upstream.

Commit a626ca6a6564 ("vm: fix vm_pgoff wrap in stack expansion") fixed
the case of an expanding mapping causing vm_pgoff wrapping when you had
downward stack expansion.  But there was another case where IA64 and
PA-RISC expand mappings: upward expansion.

This fixes that case too.

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

diff --git a/mm/mmap.c b/mm/mmap.c
index 537b36584e9a..4b80cbfd6c46 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1636,9 +1636,12 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 		size = address - vma->vm_start;
 		grow = (address - vma->vm_end) >> PAGE_SHIFT;
 
-		error = acct_stack_growth(vma, size, grow);
-		if (!error)
-			vma->vm_end = address;
+		error = -ENOMEM;
+		if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
+			error = acct_stack_growth(vma, size, grow);
+			if (!error)
+				vma->vm_end = address;
+		}
 	}
 	anon_vma_unlock(vma);
 	return error;