[024/156] mm/huge_memory: fix page_trans_huge_mapcount assumption of THP size

Commit Message

Andrew Morton Oct. 16, 2020, 2:42 a.m. UTC

From: "Matthew Wilcox (Oracle)" <[e-mail]>
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/[e-mail]
Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
Acked-by: Kirill A. Shutemov <[e-mail]>
Reviewed-by: SeongJae Park <[e-mail]>
Cc: Huang Ying <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/huge_memory.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Patch

--- 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;