From 5b8d6e37b519e455661cd847654c2e6ad20b4b1d Mon Sep 17 00:00:00 2001 From: Li Xinhai Date: Thu, 30 Jan 2020 22:13:45 -0800 Subject: [PATCH] mm/page_vma_mapped.c: explicitly compare pfn for normal, hugetlbfs and THP page When check_pte, pfn of normal, hugetlbfs and THP page need be compared. The current implementation apply comparison as - normal 4K page: page_pfn <= pfn < page_pfn + 1 - hugetlbfs page: page_pfn <= pfn < page_pfn + HPAGE_PMD_NR - THP page: page_pfn <= pfn < page_pfn + HPAGE_PMD_NR in pfn_in_hpage. For hugetlbfs page, it should be page_pfn == pfn Now, change pfn_in_hpage to pfn_is_match to highlight that comparison is not only for THP and explicitly compare for these cases. No impact upon current behavior, just make the code clear. I think it is important to make the code clear - comparing hugetlbfs page in range page_pfn <= pfn < page_pfn + HPAGE_PMD_NR is confusing. Link: http://lkml.kernel.org/r/1578737885-8890-1-git-send-email-lixinhai.lxh@gmail.com Signed-off-by: Li Xinhai Acked-by: Kirill A. Shutemov Acked-by: Mike Kravetz Cc: Kirill A. Shutemov Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_vma_mapped.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index eff4b4520c8d..719c35246cfa 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -52,12 +52,16 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw) return true; } -static inline bool pfn_in_hpage(struct page *hpage, unsigned long pfn) +static inline bool pfn_is_match(struct page *page, unsigned long pfn) { - unsigned long hpage_pfn = page_to_pfn(hpage); + unsigned long page_pfn = page_to_pfn(page); + + /* normal page and hugetlbfs page */ + if (!PageTransCompound(page) || PageHuge(page)) + return page_pfn == pfn; /* THP can be referenced by any subpage */ - return pfn >= hpage_pfn && pfn - hpage_pfn < hpage_nr_pages(hpage); + return pfn >= page_pfn && pfn - page_pfn < hpage_nr_pages(page); } /** @@ -108,7 +112,7 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw) pfn = pte_pfn(*pvmw->pte); } - return pfn_in_hpage(pvmw->page, pfn); + return pfn_is_match(pvmw->page, pfn); } /**