[patch 13/22] hugetlb: make unmap_ref_private multi-size-aware

From: Greg KH
Date: Sat Nov 15 2008 - 00:28:48 EST


2.6.27-stable review patch. If anyone has any objections, please let us know.

------------------

From: Adam Litke <agl@xxxxxxxxxx>

commit 7526674de0c921e7f1e9b6f71a1f9d832557b554 upstream.

Oops. Part of the hugetlb private reservation code was not fully
converted to use hstates.

When a huge page must be unmapped from VMAs due to a failed COW,
HPAGE_SIZE is used in the call to unmap_hugepage_range() regardless of
the page size being used. This works if the VMA is using the default
huge page size. Otherwise we might unmap too much, too little, or
trigger a BUG_ON. Rare but serious -- fix it.

Signed-off-by: Adam Litke <agl@xxxxxxxxxx>
Cc: Jon Tollefson <kniht@xxxxxxxxxxxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
mm/hugetlb.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1797,6 +1797,7 @@ int unmap_ref_private(struct mm_struct *
struct page *page,
unsigned long address)
{
+ struct hstate *h = hstate_vma(vma);
struct vm_area_struct *iter_vma;
struct address_space *mapping;
struct prio_tree_iter iter;
@@ -1806,7 +1807,7 @@ int unmap_ref_private(struct mm_struct *
* vm_pgoff is in PAGE_SIZE units, hence the different calculation
* from page cache lookup which is in HPAGE_SIZE units.
*/
- address = address & huge_page_mask(hstate_vma(vma));
+ address = address & huge_page_mask(h);
pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
+ (vma->vm_pgoff >> PAGE_SHIFT);
mapping = (struct address_space *)page_private(page);
@@ -1825,7 +1826,7 @@ int unmap_ref_private(struct mm_struct *
*/
if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
unmap_hugepage_range(iter_vma,
- address, address + HPAGE_SIZE,
+ address, address + huge_page_size(h),
page);
}


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