From: Michal Hocko <[email protected]>
Subject: hugetlb: do not use vma_hugecache_offset() for vma_prio_tree_foreach
0c176d5 ("mm: hugetlb: fix pgoff computation when unmapping page from
vma") fixed pgoff calculation but it has replaced it by
vma_hugecache_offset() which is not approapriate for offsets used for
vma_prio_tree_foreach() because that one expects index in page units
rather than in huge_page_shift.
Johannes said:
: The resulting index may not be too big, but it can be too small: assume
: hpage size of 2M and the address to unmap to be 0x200000. This is regular
: page index 512 and hpage index 1. If you have a VMA that maps the file
: only starting at the second huge page, that VMAs vm_pgoff will be 512 but
: you ask for offset 1 and miss it even though it does map the page of
: interest. hugetlb_cow() will try to unmap, miss the vma, and retry the
: cow until the allocation succeeds or the skipped vma(s) go away.
Signed-off-by: Michal Hocko <[email protected]>
Acked-by: Hillf Danton <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: KAMEZAWA Hiroyuki <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: David Rientjes <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
mm/hugetlb.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN
mm/hugetlb.c~hugetlb-do-not-use-vma_hugecache_offset-for-vma_prio_tree_foreach
mm/hugetlb.c
---
a/mm/hugetlb.c~hugetlb-do-not-use-vma_hugecache_offset-for-vma_prio_tree_foreach
+++ a/mm/hugetlb.c
@@ -2480,7 +2480,8 @@ static int unmap_ref_private(struct mm_s
* from page cache lookup which is in HPAGE_SIZE units.
*/
address = address & huge_page_mask(h);
- pgoff = vma_hugecache_offset(h, vma, address);
+ pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
+ vma->vm_pgoff;
mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
/*
_
--
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