Commit 86b562b6 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
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mm/huge_memory: fix total_mapcount assumption of page size 



File THPs may now be of arbitrary order.

Signed-off-by: default avatarKirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarSeongJae Park <sjpark@amazon.de>
Cc: Huang Ying <ying.huang@intel.com>
Link: https://lkml.kernel.org/r/20200908195539.25896-5-willy@infradead.org


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8fb156c9

mm/huge_memory.c

+5 −4
Original line number Diff line number Diff line
@@ -2494,7 +2494,7 @@ static void __split_huge_page(struct page *page, struct list_head *list, 


int total_mapcount(struct page *page)

{

	int i, compound, ret;

	int i, compound, nr, ret;



	VM_BUG_ON_PAGE(PageTail(page), page);
@@ -2502,16 +2502,17 @@ int total_mapcount(struct page *page) 
		return atomic_read(&page->_mapcount) + 1;



	compound = compound_mapcount(page);

	nr = compound_nr(page);

	if (PageHuge(page))

		return compound;

	ret = compound;

	for (i = 0; i < HPAGE_PMD_NR; i++)

	for (i = 0; i < nr; i++)

		ret += atomic_read(&page[i]._mapcount) + 1;

	/* File pages has compound_mapcount included in _mapcount */

	if (!PageAnon(page))

		return ret - compound * HPAGE_PMD_NR;

		return ret - compound * nr;

	if (PageDoubleMap(page))

		ret -= HPAGE_PMD_NR;

		ret -= nr;

	return ret;

}