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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 <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Naoya Horiguchi 2014-07-23 14:00:01 -07:00 • committed by Linus Torvalds
commit a0f7a756c2
3 changed files with 17 additions and 9 deletions
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10
mm/rmap.c
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@ -517,11 +517,7 @@ void page_unlock_anon_vma_read(struct anon_vma *anon_vma)
static inline unsigned long
__vma_address(struct page *page, struct vm_area_struct *vma)
{
pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
if (unlikely(is_vm_hugetlb_page(vma)))
pgoff = page->index << huge_page_order(page_hstate(page));
pgoff_t pgoff = page_to_pgoff(page);
return vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
}
@ -1639,7 +1635,7 @@ static struct anon_vma *rmap_walk_anon_lock(struct page *page,
static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
{
struct anon_vma *anon_vma;
pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
pgoff_t pgoff = page_to_pgoff(page);
struct anon_vma_chain *avc;
int ret = SWAP_AGAIN;
@ -1680,7 +1676,7 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
{
struct address_space *mapping = page->mapping;
pgoff_t pgoff = page->index << compound_order(page);
pgoff_t pgoff = page_to_pgoff(page);
struct vm_area_struct *vma;
int ret = SWAP_AGAIN;