[PATCH] mm/mempolicy.c: fix pgoff in mbind vma merge

Caspar Zhang
2011-08-01T15:29:47Z

commit 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4 didn't real fix the
mbind vma merge problem due to wrong pgoff value passing to vma_merge(),
which made vma_merge() always return NULL.

Re-tested the patched kernel with the reproducer provided in commit
9d8cebd, got correct result like below:

addr = 0x7ffa5aaa2000
[snip]
7ffa5aaa2000-7ffa5aaa6000 rw-p 00000000 00:00 0
7fffd556f000-7fffd5584000 rw-p 00000000 00:00 0 [stack]

Signed-off-by: Caspar Zhang <caspar@casparzhang.com>
---
mm/mempolicy.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 8b57173..b1f70d6 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -636,7 +636,6 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
struct vm_area_struct *prev;
struct vm_area_struct *vma;
int err = 0;
- pgoff_t pgoff;
unsigned long vmstart;
unsigned long vmend;

@@ -649,9 +648,9 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
vmstart = max(start, vma->vm_start);
vmend = min(end, vma->vm_end);

- pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
- vma->anon_vma, vma->vm_file, pgoff, new_pol);
+ vma->anon_vma, vma->vm_file, vma->vm_pgoff,
+ new_pol);
if (prev) {
vma = prev;
next = vma->vm_next;
--
1.7.6