From 5c7fb56e5e3f7035dd798a8e1adee639f87043e5 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 15 Jan 2016 16:56:52 -0800 Subject: [PATCH] mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd A dax-huge-page mapping while it uses some thp helpers is ultimately not a transparent huge page. The distinction is especially important in the get_user_pages() path. pmd_devmap() is used to distinguish dax-pmds from pmd_huge() and pmd_trans_huge() which have slightly different semantics. Explicitly mark the pmd_trans_huge() helpers that dax needs by adding pmd_devmap() checks. [kirill.shutemov@linux.intel.com: fix regression in handling mlocked pages in __split_huge_pmd()] Signed-off-by: Dan Williams Cc: Dave Hansen Cc: Mel Gorman Cc: Peter Zijlstra Cc: Andrea Arcangeli Cc: Matthew Wilcox Signed-off-by: Kirill A. Shutemov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/include/asm/pgtable.h | 9 +++++++- include/linux/huge_mm.h | 5 +++-- include/linux/mm.h | 7 +++++++ mm/huge_memory.c | 38 +++++++++++++++++++--------------- mm/memory.c | 8 +++---- mm/mprotect.c | 5 +++-- mm/pgtable-generic.c | 2 +- 7 files changed, 47 insertions(+), 27 deletions(-) diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 6585a8b10fea..6a0ad82c8d0f 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -164,13 +164,20 @@ static inline int pmd_large(pmd_t pte) #ifdef CONFIG_TRANSPARENT_HUGEPAGE static inline int pmd_trans_huge(pmd_t pmd) { - return pmd_val(pmd) & _PAGE_PSE; + return (pmd_val(pmd) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE; } static inline int has_transparent_hugepage(void) { return cpu_has_pse; } + +#ifdef __HAVE_ARCH_PTE_DEVMAP +static inline int pmd_devmap(pmd_t pmd) +{ + return !!(pmd_val(pmd) & _PAGE_DEVMAP); +} +#endif #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ static inline pte_t pte_set_flags(pte_t pte, pteval_t set) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 8ca35a131904..d39fa60bd6bf 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -104,7 +104,8 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, #define split_huge_pmd(__vma, __pmd, __address) \ do { \ pmd_t *____pmd = (__pmd); \ - if (pmd_trans_huge(*____pmd)) \ + if (pmd_trans_huge(*____pmd) \ + || pmd_devmap(*____pmd)) \ __split_huge_pmd(__vma, __pmd, __address); \ } while (0) @@ -124,7 +125,7 @@ static inline bool pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma, spinlock_t **ptl) { VM_BUG_ON_VMA(!rwsem_is_locked(&vma->vm_mm->mmap_sem), vma); - if (pmd_trans_huge(*pmd)) + if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) return __pmd_trans_huge_lock(pmd, vma, ptl); else return false; diff --git a/include/linux/mm.h b/include/linux/mm.h index a9902152449f..cd123272d28d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -329,6 +329,13 @@ struct inode; #define page_private(page) ((page)->private) #define set_page_private(page, v) ((page)->private = (v)) +#if !defined(__HAVE_ARCH_PTE_DEVMAP) || !defined(CONFIG_TRANSPARENT_HUGEPAGE) +static inline int pmd_devmap(pmd_t pmd) +{ + return 0; +} +#endif + /* * FIXME: take this include out, include page-flags.h in * files which need it (119 of them) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index d93706013a55..82bed2bec3ed 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -995,7 +995,7 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, ret = -EAGAIN; pmd = *src_pmd; - if (unlikely(!pmd_trans_huge(pmd))) { + if (unlikely(!pmd_trans_huge(pmd) && !pmd_devmap(pmd))) { pte_free(dst_mm, pgtable); goto out_unlock; } @@ -1018,17 +1018,20 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, goto out_unlock; } - src_page = pmd_page(pmd); - VM_BUG_ON_PAGE(!PageHead(src_page), src_page); - get_page(src_page); - page_dup_rmap(src_page, true); - add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); + if (pmd_trans_huge(pmd)) { + /* thp accounting separate from pmd_devmap accounting */ + src_page = pmd_page(pmd); + VM_BUG_ON_PAGE(!PageHead(src_page), src_page); + get_page(src_page); + page_dup_rmap(src_page, true); + add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); + atomic_long_inc(&dst_mm->nr_ptes); + pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); + } pmdp_set_wrprotect(src_mm, addr, src_pmd); pmd = pmd_mkold(pmd_wrprotect(pmd)); - pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); set_pmd_at(dst_mm, addr, dst_pmd, pmd); - atomic_long_inc(&dst_mm->nr_ptes); ret = 0; out_unlock: @@ -1716,7 +1719,7 @@ bool __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma, spinlock_t **ptl) { *ptl = pmd_lock(vma->vm_mm, pmd); - if (likely(pmd_trans_huge(*pmd))) + if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd))) return true; spin_unlock(*ptl); return false; @@ -2788,7 +2791,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); VM_BUG_ON_VMA(vma->vm_start > haddr, vma); VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); - VM_BUG_ON(!pmd_trans_huge(*pmd)); + VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)); count_vm_event(THP_SPLIT_PMD); @@ -2901,14 +2904,15 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE); ptl = pmd_lock(mm, pmd); - if (unlikely(!pmd_trans_huge(*pmd))) + if (pmd_trans_huge(*pmd)) { + page = pmd_page(*pmd); + if (PageMlocked(page)) + get_page(page); + else + page = NULL; + } else if (!pmd_devmap(*pmd)) goto out; - page = pmd_page(*pmd); __split_huge_pmd_locked(vma, pmd, haddr, false); - if (PageMlocked(page)) - get_page(page); - else - page = NULL; out: spin_unlock(ptl); mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE); @@ -2938,7 +2942,7 @@ static void split_huge_pmd_address(struct vm_area_struct *vma, return; pmd = pmd_offset(pud, address); - if (!pmd_present(*pmd) || !pmd_trans_huge(*pmd)) + if (!pmd_present(*pmd) || (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd))) return; /* * Caller holds the mmap_sem write mode, so a huge pmd cannot diff --git a/mm/memory.c b/mm/memory.c index 552ae3d69435..ff17850a52d9 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -950,7 +950,7 @@ static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src src_pmd = pmd_offset(src_pud, addr); do { next = pmd_addr_end(addr, end); - if (pmd_trans_huge(*src_pmd)) { + if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) { int err; VM_BUG_ON(next-addr != HPAGE_PMD_SIZE); err = copy_huge_pmd(dst_mm, src_mm, @@ -1177,7 +1177,7 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, pmd = pmd_offset(pud, addr); do { next = pmd_addr_end(addr, end); - if (pmd_trans_huge(*pmd)) { + if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { if (next - addr != HPAGE_PMD_SIZE) { #ifdef CONFIG_DEBUG_VM if (!rwsem_is_locked(&tlb->mm->mmap_sem)) { @@ -3375,7 +3375,7 @@ static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, int ret; barrier(); - if (pmd_trans_huge(orig_pmd)) { + if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) { unsigned int dirty = flags & FAULT_FLAG_WRITE; if (pmd_protnone(orig_pmd)) @@ -3404,7 +3404,7 @@ static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, unlikely(__pte_alloc(mm, vma, pmd, address))) return VM_FAULT_OOM; /* if an huge pmd materialized from under us just retry later */ - if (unlikely(pmd_trans_huge(*pmd))) + if (unlikely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd))) return 0; /* * A regular pmd is established and it can't morph into a huge pmd diff --git a/mm/mprotect.c b/mm/mprotect.c index 6047707085c1..8eb7bb40dc40 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -149,7 +149,8 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, unsigned long this_pages; next = pmd_addr_end(addr, end); - if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd)) + if (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd) + && pmd_none_or_clear_bad(pmd)) continue; /* invoke the mmu notifier if the pmd is populated */ @@ -158,7 +159,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, mmu_notifier_invalidate_range_start(mm, mni_start, end); } - if (pmd_trans_huge(*pmd)) { + if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { if (next - addr != HPAGE_PMD_SIZE) split_huge_pmd(vma, pmd, addr); else { diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c index c311a2ec6fea..9d4767698a1c 100644 --- a/mm/pgtable-generic.c +++ b/mm/pgtable-generic.c @@ -132,7 +132,7 @@ pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address, { pmd_t pmd; VM_BUG_ON(address & ~HPAGE_PMD_MASK); - VM_BUG_ON(!pmd_trans_huge(*pmdp)); + VM_BUG_ON(!pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp)); pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp); flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); return pmd; -- 2.20.1