From 49fd0f957db7074ed60ba9993a6e230b5c866e6d Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 9 Nov 2012 14:04:08 +1100 Subject: [PATCH] mm: thp: set the accessed flag for old pages on access fault On x86 memory accesses to pages without the ACCESSED flag set result in the ACCESSED flag being set automatically. With the ARM architecture a page access fault is raised instead (and it will continue to be raised until the ACCESSED flag is set for the appropriate PTE/PMD). For normal memory pages, handle_pte_fault will call pte_mkyoung (effectively setting the ACCESSED flag). For transparent huge pages, pmd_mkyoung will only be called for a write fault. This patch ensures that faults on transparent hugepages which do not result in a CoW update the access flags for the faulting pmd. Signed-off-by: Will Deacon Cc: Chris Metcalf Acked-by: Kirill A. Shutemov Cc: Andrea Arcangeli Acked-by: Johannes Weiner Cc: Ni zhan Chen Signed-off-by: Andrew Morton --- include/linux/huge_mm.h | 4 ++++ mm/huge_memory.c | 22 ++++++++++++++++++++++ mm/memory.c | 7 ++++++- 3 files changed, 32 insertions(+), 1 deletion(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 4f0f94860138..766fb27bf13f 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -8,6 +8,10 @@ extern int do_huge_pmd_anonymous_page(struct mm_struct *mm, extern int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, struct vm_area_struct *vma); +extern void huge_pmd_set_accessed(struct mm_struct *mm, + struct vm_area_struct *vma, + unsigned long address, pmd_t *pmd, + pmd_t orig_pmd, int dirty); extern int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, pmd_t *pmd, pmd_t orig_pmd); diff --git a/mm/huge_memory.c b/mm/huge_memory.c index f1c267971198..fc77f1b5118c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -932,6 +932,28 @@ out: return ret; } +void huge_pmd_set_accessed(struct mm_struct *mm, + struct vm_area_struct *vma, + unsigned long address, + pmd_t *pmd, pmd_t orig_pmd, + int dirty) +{ + pmd_t entry; + unsigned long haddr; + + spin_lock(&mm->page_table_lock); + if (unlikely(!pmd_same(*pmd, orig_pmd))) + goto unlock; + + entry = pmd_mkyoung(orig_pmd); + haddr = address & HPAGE_PMD_MASK; + if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty)) + update_mmu_cache_pmd(vma, address, pmd); + +unlock: + spin_unlock(&mm->page_table_lock); +} + static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, diff --git a/mm/memory.c b/mm/memory.c index 9b7acd685b36..f88d931c5a46 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3646,12 +3646,14 @@ retry: barrier(); if (pmd_trans_huge(orig_pmd) && !pmd_trans_splitting(orig_pmd)) { + unsigned int dirty = flags & FAULT_FLAG_WRITE; + if (pmd_numa(vma, orig_pmd)) { do_huge_pmd_numa_page(mm, vma, address, pmd, flags, orig_pmd); } - if ((flags & FAULT_FLAG_WRITE) && !pmd_write(orig_pmd)) { + if (dirty && !pmd_write(orig_pmd)) { ret = do_huge_pmd_wp_page(mm, vma, address, pmd, orig_pmd); /* @@ -3661,6 +3663,9 @@ retry: */ if (unlikely(ret & VM_FAULT_OOM)) goto retry; + } else { + huge_pmd_set_accessed(mm, vma, address, pmd, + orig_pmd, dirty); } return ret; -- 2.39.5