From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Subject: mm/huge_memory: fix page_trans_huge_mapcount assumption of THP size Ask the page what size it is instead of assuming it's PMD size. Link: https://lkml.kernel.org/r/20200908195539.25896-7-willy@xxxxxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reviewed-by: SeongJae Park <sjpark@xxxxxxxxx> Cc: Huang Ying <ying.huang@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/huge_memory.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/huge_memory.c~mm-huge_memory-fix-page_trans_huge_mapcount-assumption-of-thp-size +++ a/mm/huge_memory.c @@ -2558,14 +2558,14 @@ int page_trans_huge_mapcount(struct page page = compound_head(page); _total_mapcount = ret = 0; - for (i = 0; i < HPAGE_PMD_NR; i++) { + for (i = 0; i < thp_nr_pages(page); i++) { mapcount = atomic_read(&page[i]._mapcount) + 1; ret = max(ret, mapcount); _total_mapcount += mapcount; } if (PageDoubleMap(page)) { ret -= 1; - _total_mapcount -= HPAGE_PMD_NR; + _total_mapcount -= thp_nr_pages(page); } mapcount = compound_mapcount(page); ret += mapcount; _
