Messages in this thread Patch in this message | | | Date | Tue, 8 Jun 2021 21:27:45 -0700 (PDT) | From | Hugh Dickins <> | Subject | [PATCH v2 09/10] mm/thp: remap_page() is only needed on anonymous THP |
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THP splitting's unmap_page() only sets TTU_SPLIT_FREEZE when PageAnon, and migration entries are only inserted when TTU_MIGRATION (unused here) or TTU_SPLIT_FREEZE is set: so it's just a waste of time for remap_page() to search for migration entries to remove when !PageAnon.
Fixes: baa355fd3314 ("thp: file pages support for split_huge_page()") Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> --- mm/huge_memory.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 6d2a0119fc58..319a1a078451 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2355,6 +2355,7 @@ static void unmap_page(struct page *page) VM_BUG_ON_PAGE(!PageHead(page), page); + /* If TTU_SPLIT_FREEZE is ever extended to file, update remap_page() */ if (PageAnon(page)) ttu_flags |= TTU_SPLIT_FREEZE; @@ -2366,6 +2367,10 @@ static void unmap_page(struct page *page) static void remap_page(struct page *page, unsigned int nr) { int i; + + /* If TTU_SPLIT_FREEZE is ever extended to file, remove this check */ + if (!PageAnon(page)) + return; if (PageTransHuge(page)) { remove_migration_ptes(page, page, true); } else { -- 2.26.2
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