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mm/rmap.c: fix pgoff calculation to handle hugepage correctly

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I triggered VM_BUG_ON() in vma_address() when I tried to migrate an
anonymous hugepage with mbind() in the kernel v3.16-rc3.  This is
because pgoff's calculation in rmap_walk_anon() fails to consider
compound_order() only to have an incorrect value.

This patch introduces page_to_pgoff(), which gets the page's offset in
PAGE_CACHE_SIZE.

Kirill pointed out that page cache tree should natively handle
hugepages, and in order to make hugetlbfs fit it, page->index of
hugetlbfs page should be in PAGE_CACHE_SIZE.  This is beyond this patch,
but page_to_pgoff() contains the point to be fixed in a single function.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Naoya Horiguchi
2014-07-23 14:00:01 -07:00
committed by Linus Torvalds
parent aed8adb768
commit a0f7a756c2
3 changed files with 17 additions and 9 deletions
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12
include/linux/pagemap.h
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@@ -398,6 +398,18 @@ static inline struct page *read_mapping_page(struct address_space *mapping,
return read_cache_page(mapping, index, filler, data);
}
/*
* Get the offset in PAGE_SIZE.
* (TODO: hugepage should have ->index in PAGE_SIZE)
*/
static inline pgoff_t page_to_pgoff(struct page *page)
{
if (unlikely(PageHeadHuge(page)))
return page->index << compound_order(page);
else
return page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
}
/*
* Return byte-offset into filesystem object for page.
*/