mm: hugetlb: fix pgoff computation when unmapping page from vma
Hillf Danton [Tue, 10 Jan 2012 23:08:19 +0000 (15:08 -0800)]
The computation for pgoff is incorrect, at least with

(vma->vm_pgoff >> PAGE_SHIFT)

involved.  It is fixed with the available method if HPAGE_SIZE is
concerned in page cache lookup.

[akpm@linux-foundation.org: use vma_hugecache_offset() directly, per Michal]
Signed-off-by: Hillf Danton <dhillf@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb.c

index ab89d6f..bb7dc40 100644 (file)
@@ -2315,8 +2315,7 @@ static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
         * from page cache lookup which is in HPAGE_SIZE units.
         */
        address = address & huge_page_mask(h);
-       pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
-               + (vma->vm_pgoff >> PAGE_SHIFT);
+       pgoff = vma_hugecache_offset(h, vma, address);
        mapping = (struct address_space *)page_private(page);
 
        /*