From dcb32d9913b7ed527b135a7e221f8d14b67bb952 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Thu, 7 Jul 2016 17:19:15 -0700 Subject: x86/mm: Use pte_none() to test for empty PTE The page table manipulation code seems to have grown a couple of sites that are looking for empty PTEs. Just in case one of these entries got a stray bit set, use pte_none() instead of checking for a zero pte_val(). The use pte_same() makes me a bit nervous. If we were doing a pte_same() check against two cleared entries and one of them had a stray bit set, it might fail the pte_same() check. But, I don't think we ever _do_ pte_same() for cleared entries. It is almost entirely used for checking for races in fault-in paths. Signed-off-by: Dave Hansen Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Toshi Kani Cc: dave.hansen@intel.com Cc: linux-mm@kvack.org Cc: mhocko@suse.com Link: http://lkml.kernel.org/r/20160708001915.813703D9@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/mm/pgtable_32.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/mm/pgtable_32.c') diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c index 75cc0978d45d..e67ae0e6c59d 100644 --- a/arch/x86/mm/pgtable_32.c +++ b/arch/x86/mm/pgtable_32.c @@ -47,7 +47,7 @@ void set_pte_vaddr(unsigned long vaddr, pte_t pteval) return; } pte = pte_offset_kernel(pmd, vaddr); - if (pte_val(pteval)) + if (!pte_none(pteval)) set_pte_at(&init_mm, vaddr, pte, pteval); else pte_clear(&init_mm, vaddr, pte); -- cgit v1.2.3