From: Hillf Danton <dhillf@gmail.com>
Date: Tue, 10 Jan 2012 23:08:19 +0000 (-0800)
Subject: mm: hugetlb: fix pgoff computation when unmapping page from vma
X-Git-Tag: v4.13~12816^2~87
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=0c176d52b0b2619f231b2bbf329b90c028134f58;p=mirror_ubuntu-bionic-kernel.git

mm: hugetlb: fix pgoff computation when unmapping page from vma

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>
---

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ab89d6f382d1..bb7dc405634f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -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);
 
 	/*