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    Subject[PATCH 5.4 10/17] mm: simplify follow_pte{,pmd}
    Date
    From: Christoph Hellwig <hch@lst.de>

    commit ff5c19ed4b087073cea38ff0edc80c23d7256943 upstream.

    Merge __follow_pte_pmd, follow_pte_pmd and follow_pte into a single
    follow_pte function and just pass two additional NULL arguments for the
    two previous follow_pte callers.

    [sfr@canb.auug.org.au: merge fix for "s390/pci: remove races against pte updates"]
    Link: https://lkml.kernel.org/r/20201111221254.7f6a3658@canb.auug.org.au

    Link: https://lkml.kernel.org/r/20201029101432.47011-3-hch@lst.de
    Signed-off-by: Christoph Hellwig <hch@lst.de>
    Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
    Cc: Daniel Vetter <daniel@ffwll.ch>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Nick Desaulniers <ndesaulniers@google.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    fs/dax.c | 9 ++++-----
    include/linux/mm.h | 6 +++---
    mm/memory.c | 35 +++++------------------------------
    3 files changed, 12 insertions(+), 38 deletions(-)

    --- a/fs/dax.c
    +++ b/fs/dax.c
    @@ -794,12 +794,11 @@ static void dax_entry_mkclean(struct add
    address = pgoff_address(index, vma);

    /*
    - * Note because we provide range to follow_pte_pmd it will
    - * call mmu_notifier_invalidate_range_start() on our behalf
    - * before taking any lock.
    + * Note because we provide range to follow_pte it will call
    + * mmu_notifier_invalidate_range_start() on our behalf before
    + * taking any lock.
    */
    - if (follow_pte_pmd(vma->vm_mm, address, &range,
    - &ptep, &pmdp, &ptl))
    + if (follow_pte(vma->vm_mm, address, &range, &ptep, &pmdp, &ptl))
    continue;

    /*
    --- a/include/linux/mm.h
    +++ b/include/linux/mm.h
    @@ -1466,9 +1466,9 @@ void free_pgd_range(struct mmu_gather *t
    unsigned long end, unsigned long floor, unsigned long ceiling);
    int copy_page_range(struct mm_struct *dst, struct mm_struct *src,
    struct vm_area_struct *vma);
    -int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
    - struct mmu_notifier_range *range,
    - pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp);
    +int follow_pte(struct mm_struct *mm, unsigned long address,
    + struct mmu_notifier_range *range, pte_t **ptepp, pmd_t **pmdpp,
    + spinlock_t **ptlp);
    int follow_pfn(struct vm_area_struct *vma, unsigned long address,
    unsigned long *pfn);
    int follow_phys(struct vm_area_struct *vma, unsigned long address,
    --- a/mm/memory.c
    +++ b/mm/memory.c
    @@ -4222,9 +4222,9 @@ int __pmd_alloc(struct mm_struct *mm, pu
    }
    #endif /* __PAGETABLE_PMD_FOLDED */

    -static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
    - struct mmu_notifier_range *range,
    - pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
    +int follow_pte(struct mm_struct *mm, unsigned long address,
    + struct mmu_notifier_range *range, pte_t **ptepp, pmd_t **pmdpp,
    + spinlock_t **ptlp)
    {
    pgd_t *pgd;
    p4d_t *p4d;
    @@ -4289,31 +4289,6 @@ out:
    return -EINVAL;
    }

    -static inline int follow_pte(struct mm_struct *mm, unsigned long address,
    - pte_t **ptepp, spinlock_t **ptlp)
    -{
    - int res;
    -
    - /* (void) is needed to make gcc happy */
    - (void) __cond_lock(*ptlp,
    - !(res = __follow_pte_pmd(mm, address, NULL,
    - ptepp, NULL, ptlp)));
    - return res;
    -}
    -
    -int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
    - struct mmu_notifier_range *range,
    - pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
    -{
    - int res;
    -
    - /* (void) is needed to make gcc happy */
    - (void) __cond_lock(*ptlp,
    - !(res = __follow_pte_pmd(mm, address, range,
    - ptepp, pmdpp, ptlp)));
    - return res;
    -}
    -
    /**
    * follow_pfn - look up PFN at a user virtual address
    * @vma: memory mapping
    @@ -4334,7 +4309,7 @@ int follow_pfn(struct vm_area_struct *vm
    if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
    return ret;

    - ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
    + ret = follow_pte(vma->vm_mm, address, NULL, &ptep, NULL, &ptl);
    if (ret)
    return ret;
    *pfn = pte_pfn(*ptep);
    @@ -4355,7 +4330,7 @@ int follow_phys(struct vm_area_struct *v
    if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
    goto out;

    - if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
    + if (follow_pte(vma->vm_mm, address, NULL, &ptep, NULL, &ptl))
    goto out;
    pte = *ptep;


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