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Commit 5cbc198a authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

mm: fix false-positive WARN_ON() in truncate/invalidate for hugetlb 

Hugetlb pages have ->index in size of the huge pages (PMD_SIZE or
PUD_SIZE), not in PAGE_SIZE as other types of pages.  This means we
cannot user page_to_pgoff() to check whether we've got the right page
for the radix-tree index.

Let's introduce page_to_index() which would return radix-tree index for
given page.

We will be able to get rid of this once hugetlb will be switched to
multi-order entries.

Fixes: fc127da0 ("truncate: handle file thp")
Link: http://lkml.kernel.org/r/20161123093053.mjbnvn5zwxw5e6lk@black.fi.intel.com


Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: default avatarDoug Nelson <doug.nelson@intel.com>
Tested-by: default avatarDoug Nelson <doug.nelson@intel.com>
Reviewed-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 828347f8

include/linux/pagemap.h

+15 −6
Original line number Diff line number Diff line
@@ -374,16 +374,13 @@ static inline struct page *read_mapping_page(struct address_space *mapping, 
}



/*

 * Get the offset in PAGE_SIZE.

 * (TODO: hugepage should have ->index in PAGE_SIZE)

 * Get index of the page with in radix-tree

 * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)

 */

static inline pgoff_t page_to_pgoff(struct page *page)

static inline pgoff_t page_to_index(struct page *page)

{

	pgoff_t pgoff;



	if (unlikely(PageHeadHuge(page)))

		return page->index << compound_order(page);



	if (likely(!PageTransTail(page)))

		return page->index;
@@ -396,6 +393,18 @@ static inline pgoff_t page_to_pgoff(struct page *page) 
	return pgoff;

}



/*

 * 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);



	return page_to_index(page);

}



/*

 * Return byte-offset into filesystem object for page.

 */

mm/truncate.c

+4 −4
Original line number Diff line number Diff line
@@ -283,7 +283,7 @@ void truncate_inode_pages_range(struct address_space *mapping, 


			if (!trylock_page(page))

				continue;

			WARN_ON(page_to_pgoff(page) != index);

			WARN_ON(page_to_index(page) != index);

			if (PageWriteback(page)) {

				unlock_page(page);

				continue;
@@ -371,7 +371,7 @@ void truncate_inode_pages_range(struct address_space *mapping, 
			}



			lock_page(page);

			WARN_ON(page_to_pgoff(page) != index);

			WARN_ON(page_to_index(page) != index);

			wait_on_page_writeback(page);

			truncate_inode_page(mapping, page);

			unlock_page(page);
@@ -492,7 +492,7 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping, 
			if (!trylock_page(page))

				continue;



			WARN_ON(page_to_pgoff(page) != index);

			WARN_ON(page_to_index(page) != index);



			/* Middle of THP: skip */

			if (PageTransTail(page)) {
@@ -612,7 +612,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping, 
			}



			lock_page(page);

			WARN_ON(page_to_pgoff(page) != index);

			WARN_ON(page_to_index(page) != index);

			if (page->mapping != mapping) {

				unlock_page(page);

				continue;