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    Subject[PATCH 20 of 66] pte alloc trans splitting
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    From: Andrea Arcangeli <aarcange@redhat.com>

    pte alloc routines must wait for split_huge_page if the pmd is not
    present and not null (i.e. pmd_trans_splitting). The additional
    branches are optimized away at compile time by pmd_trans_splitting if
    the config option is off. However we must pass the vma down in order
    to know the anon_vma lock to wait for.

    Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
    Acked-by: Rik van Riel <riel@redhat.com>
    Acked-by: Mel Gorman <mel@csn.ul.ie>
    ---

    diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
    --- a/arch/x86/kernel/tboot.c
    +++ b/arch/x86/kernel/tboot.c
    @@ -133,7 +133,7 @@ static int map_tboot_page(unsigned long
    pmd = pmd_alloc(&tboot_mm, pud, vaddr);
    if (!pmd)
    return -1;
    - pte = pte_alloc_map(&tboot_mm, pmd, vaddr);
    + pte = pte_alloc_map(&tboot_mm, NULL, pmd, vaddr);
    if (!pte)
    return -1;
    set_pte_at(&tboot_mm, vaddr, pte, pfn_pte(pfn, prot));
    diff --git a/include/linux/mm.h b/include/linux/mm.h
    --- a/include/linux/mm.h
    +++ b/include/linux/mm.h
    @@ -1117,7 +1117,8 @@ static inline int __pmd_alloc(struct mm_
    int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address);
    #endif

    -int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address);
    +int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
    + pmd_t *pmd, unsigned long address);
    int __pte_alloc_kernel(pmd_t *pmd, unsigned long address);

    /*
    @@ -1186,16 +1187,18 @@ static inline void pgtable_page_dtor(str
    pte_unmap(pte); \
    } while (0)

    -#define pte_alloc_map(mm, pmd, address) \
    - ((unlikely(!pmd_present(*(pmd))) && __pte_alloc(mm, pmd, address))? \
    - NULL: pte_offset_map(pmd, address))
    +#define pte_alloc_map(mm, vma, pmd, address) \
    + ((unlikely(pmd_none(*(pmd))) && __pte_alloc(mm, vma, \
    + pmd, address))? \
    + NULL: pte_offset_map(pmd, address))

    #define pte_alloc_map_lock(mm, pmd, address, ptlp) \
    - ((unlikely(!pmd_present(*(pmd))) && __pte_alloc(mm, pmd, address))? \
    + ((unlikely(pmd_none(*(pmd))) && __pte_alloc(mm, NULL, \
    + pmd, address))? \
    NULL: pte_offset_map_lock(mm, pmd, address, ptlp))

    #define pte_alloc_kernel(pmd, address) \
    - ((unlikely(!pmd_present(*(pmd))) && __pte_alloc_kernel(pmd, address))? \
    + ((unlikely(pmd_none(*(pmd))) && __pte_alloc_kernel(pmd, address))? \
    NULL: pte_offset_kernel(pmd, address))

    extern void free_area_init(unsigned long * zones_size);
    diff --git a/mm/memory.c b/mm/memory.c
    --- a/mm/memory.c
    +++ b/mm/memory.c
    @@ -394,9 +394,11 @@ void free_pgtables(struct mmu_gather *tl
    }
    }

    -int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
    +int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
    + pmd_t *pmd, unsigned long address)
    {
    pgtable_t new = pte_alloc_one(mm, address);
    + int wait_split_huge_page;
    if (!new)
    return -ENOMEM;

    @@ -416,14 +418,18 @@ int __pte_alloc(struct mm_struct *mm, pm
    smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */

    spin_lock(&mm->page_table_lock);
    - if (!pmd_present(*pmd)) { /* Has another populated it ? */
    + wait_split_huge_page = 0;
    + if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
    mm->nr_ptes++;
    pmd_populate(mm, pmd, new);
    new = NULL;
    - }
    + } else if (unlikely(pmd_trans_splitting(*pmd)))
    + wait_split_huge_page = 1;
    spin_unlock(&mm->page_table_lock);
    if (new)
    pte_free(mm, new);
    + if (wait_split_huge_page)
    + wait_split_huge_page(vma->anon_vma, pmd);
    return 0;
    }

    @@ -436,10 +442,11 @@ int __pte_alloc_kernel(pmd_t *pmd, unsig
    smp_wmb(); /* See comment in __pte_alloc */

    spin_lock(&init_mm.page_table_lock);
    - if (!pmd_present(*pmd)) { /* Has another populated it ? */
    + if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
    pmd_populate_kernel(&init_mm, pmd, new);
    new = NULL;
    - }
    + } else
    + VM_BUG_ON(pmd_trans_splitting(*pmd));
    spin_unlock(&init_mm.page_table_lock);
    if (new)
    pte_free_kernel(&init_mm, new);
    @@ -3215,7 +3222,7 @@ int handle_mm_fault(struct mm_struct *mm
    pmd = pmd_alloc(mm, pud, address);
    if (!pmd)
    return VM_FAULT_OOM;
    - pte = pte_alloc_map(mm, pmd, address);
    + pte = pte_alloc_map(mm, vma, pmd, address);
    if (!pte)
    return VM_FAULT_OOM;

    diff --git a/mm/mremap.c b/mm/mremap.c
    --- a/mm/mremap.c
    +++ b/mm/mremap.c
    @@ -47,7 +47,8 @@ static pmd_t *get_old_pmd(struct mm_stru
    return pmd;
    }

    -static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr)
    +static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
    + unsigned long addr)
    {
    pgd_t *pgd;
    pud_t *pud;
    @@ -62,7 +63,8 @@ static pmd_t *alloc_new_pmd(struct mm_st
    if (!pmd)
    return NULL;

    - if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr))
    + VM_BUG_ON(pmd_trans_huge(*pmd));
    + if (pmd_none(*pmd) && __pte_alloc(mm, vma, pmd, addr))
    return NULL;

    return pmd;
    @@ -147,7 +149,7 @@ unsigned long move_page_tables(struct vm
    old_pmd = get_old_pmd(vma->vm_mm, old_addr);
    if (!old_pmd)
    continue;
    - new_pmd = alloc_new_pmd(vma->vm_mm, new_addr);
    + new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
    if (!new_pmd)
    break;
    next = (new_addr + PMD_SIZE) & PMD_MASK;

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      Last update: 2010-11-03 16:47    [W:0.029 / U:60.904 seconds]
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