From c46a7c817e662a820373bb76b88d0ad67d6abe5d Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Wed, 4 Jun 2014 16:06:30 -0700 Subject: x86: define _PAGE_NUMA by reusing software bits on the PMD and PTE levels _PAGE_NUMA is currently an alias of _PROT_PROTNONE to trap NUMA hinting faults on x86. Care is taken such that _PAGE_NUMA is used only in situations where the VMA flags distinguish between NUMA hinting faults and prot_none faults. This decision was x86-specific and conceptually it is difficult requiring special casing to distinguish between PROTNONE and NUMA ptes based on context. Fundamentally, we only need the _PAGE_NUMA bit to tell the difference between an entry that is really unmapped and a page that is protected for NUMA hinting faults as if the PTE is not present then a fault will be trapped. Swap PTEs on x86-64 use the bits after _PAGE_GLOBAL for the offset. This patch shrinks the maximum possible swap size and uses the bit to uniquely distinguish between NUMA hinting ptes and swap ptes. Signed-off-by: Mel Gorman Cc: David Vrabel Cc: Ingo Molnar Cc: Peter Anvin Cc: Fengguang Wu Cc: Linus Torvalds Cc: Steven Noonan Cc: Rik van Riel Cc: Peter Zijlstra Cc: Andrea Arcangeli Cc: Dave Hansen Cc: Srikar Dronamraju Cc: Cyrill Gorcunov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-generic/pgtable.h | 8 ++++++-- include/linux/swapops.h | 2 +- 2 files changed, 7 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index a8015a7a55bb..53b2acc38213 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -233,6 +233,10 @@ static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b) # define pte_accessible(mm, pte) ((void)(pte), 1) #endif +#ifndef pte_present_nonuma +#define pte_present_nonuma(pte) pte_present(pte) +#endif + #ifndef flush_tlb_fix_spurious_fault #define flush_tlb_fix_spurious_fault(vma, address) flush_tlb_page(vma, address) #endif @@ -670,7 +674,7 @@ static inline int pmd_trans_unstable(pmd_t *pmd) static inline int pte_numa(pte_t pte) { return (pte_flags(pte) & - (_PAGE_NUMA|_PAGE_PRESENT)) == _PAGE_NUMA; + (_PAGE_NUMA|_PAGE_PROTNONE|_PAGE_PRESENT)) == _PAGE_NUMA; } #endif @@ -678,7 +682,7 @@ static inline int pte_numa(pte_t pte) static inline int pmd_numa(pmd_t pmd) { return (pmd_flags(pmd) & - (_PAGE_NUMA|_PAGE_PRESENT)) == _PAGE_NUMA; + (_PAGE_NUMA|_PAGE_PROTNONE|_PAGE_PRESENT)) == _PAGE_NUMA; } #endif diff --git a/include/linux/swapops.h b/include/linux/swapops.h index c0f75261a728..6adfb7bfbf44 100644 --- a/include/linux/swapops.h +++ b/include/linux/swapops.h @@ -54,7 +54,7 @@ static inline pgoff_t swp_offset(swp_entry_t entry) /* check whether a pte points to a swap entry */ static inline int is_swap_pte(pte_t pte) { - return !pte_none(pte) && !pte_present(pte) && !pte_file(pte); + return !pte_none(pte) && !pte_present_nonuma(pte) && !pte_file(pte); } #endif -- cgit v1.2.3-70-g09d2