From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Subject: mm/filemap: fix page cache removal for arbitrary sized THPs Patch series "Remove assumptions of THP size". There are a number of places in the VM which assume that a THP is a PMD in size. That's true today, and remains true after this patch series, but this is a prerequisite for switching to arbitrary-sized THPs. thp_nr_pages() still returns either HPAGE_PMD_NR or 1, but will be changed later. This patch (of 11): page_cache_free_page() assumes THPs are PMD_SIZE; fix that assumption. Link: https://lkml.kernel.org/r/20200908195539.25896-1-willy@xxxxxxxxxxxxx Link: https://lkml.kernel.org/r/20200908195539.25896-2-willy@xxxxxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Huang Ying <ying.huang@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/filemap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/filemap.c~mm-filemap-fix-page-cache-removal-for-arbitrary-sized-thps +++ a/mm/filemap.c @@ -249,7 +249,7 @@ static void page_cache_free_page(struct freepage(page); if (PageTransHuge(page) && !PageHuge(page)) { - page_ref_sub(page, HPAGE_PMD_NR); + page_ref_sub(page, thp_nr_pages(page)); VM_BUG_ON_PAGE(page_count(page) <= 0, page); } else { put_page(page); _
