[025/156] mm/huge_memory: fix can_split_huge_page 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 can_split_huge_page assumption of THP size

Ask the page how many subpages it has 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]>
Acked-by: "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-can_split_huge_page-assumption-of-thp-size
+++ a/mm/huge_memory.c
@@ -2582,9 +2582,9 @@  bool can_split_huge_page(struct page *pa
 
 	/* Additional pins from page cache */
 	if (PageAnon(page))
-		extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
+		extra_pins = PageSwapCache(page) ? thp_nr_pages(page) : 0;
 	else
-		extra_pins = HPAGE_PMD_NR;
+		extra_pins = thp_nr_pages(page);
 	if (pextra_pins)
 		*pextra_pins = extra_pins;
 	return total_mapcount(page) == page_count(page) - extra_pins - 1;