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Subject[104/107] vm: fix vm_pgoff wrap in upward expansion
2.6.32-longterm review patch.  If anyone has any objections, please let us know.

------------------
From: Hugh Dickins <hughd@google.com>

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>

---
mm/mmap.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1636,9 +1636,12 @@ int expand_upwards(struct vm_area_struct
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;



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