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mm/huge_memory: fix total_mapcount assumption of page size

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File THPs may now be of arbitrary order.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: SeongJae 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: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2020-10-15 20:05:33 -07:00 committed by Linus Torvalds
parent 8fb156c9ee
commit 86b562b629
1 changed files with 5 additions and 4 deletions
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9
mm/huge_memory.c
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@ -2494,7 +2494,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
int total_mapcount(struct page *page) int total_mapcount(struct page *page)
{ {
int i, compound, ret; int i, compound, nr, ret;
VM_BUG_ON_PAGE(PageTail(page), page); VM_BUG_ON_PAGE(PageTail(page), page);
@ -2502,16 +2502,17 @@ int total_mapcount(struct page *page)
return atomic_read(&page->_mapcount) + 1; return atomic_read(&page->_mapcount) + 1;
compound = compound_mapcount(page); compound = compound_mapcount(page);
nr = compound_nr(page);
if (PageHuge(page)) if (PageHuge(page))
return compound; return compound;
ret = compound; ret = compound;
for (i = 0; i < HPAGE_PMD_NR; i++) for (i = 0; i < nr; i++)
ret += atomic_read(&page[i]._mapcount) + 1; ret += atomic_read(&page[i]._mapcount) + 1;
/* File pages has compound_mapcount included in _mapcount */ /* File pages has compound_mapcount included in _mapcount */
if (!PageAnon(page)) if (!PageAnon(page))
return ret - compound * HPAGE_PMD_NR; return ret - compound * nr;
if (PageDoubleMap(page)) if (PageDoubleMap(page))
ret -= HPAGE_PMD_NR; ret -= nr;
return ret; return ret;
} }