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 3e2f805c964e768244be40f860b72897777dadc8..25a3783c25e336d5352ba532760219326537c786 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1677,9 +1677,12 @@ 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;