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    Subject[PATCH v4 05/13] clear_refs: remove clear_refs_private->vma and introduce clear_refs_test_walk()
    Date
    clear_refs_write() has some prechecks to determine if we really walk over
    a given vma. Now we have a test_walk() callback to filter vmas, so let's
    utilize it.

    ChangeLog v4:
    - use walk_page_range instead of walk_page_vma with for loop

    Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
    Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    ---
    fs/proc/task_mmu.c | 54 ++++++++++++++++++++++++++----------------------------
    1 file changed, 26 insertions(+), 28 deletions(-)

    diff --git v3.16-rc3.orig/fs/proc/task_mmu.c v3.16-rc3/fs/proc/task_mmu.c
    index 3067bf08393b..df9f368e01b7 100644
    --- v3.16-rc3.orig/fs/proc/task_mmu.c
    +++ v3.16-rc3/fs/proc/task_mmu.c
    @@ -715,7 +715,6 @@ enum clear_refs_types {
    };

    struct clear_refs_private {
    - struct vm_area_struct *vma;
    enum clear_refs_types type;
    };

    @@ -748,7 +747,7 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
    unsigned long end, struct mm_walk *walk)
    {
    struct clear_refs_private *cp = walk->private;
    - struct vm_area_struct *vma = cp->vma;
    + struct vm_area_struct *vma = walk->vma;
    pte_t *pte, ptent;
    spinlock_t *ptl;
    struct page *page;
    @@ -782,6 +781,29 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
    return 0;
    }

    +static int clear_refs_test_walk(unsigned long start, unsigned long end,
    + struct mm_walk *walk)
    +{
    + struct clear_refs_private *cp = walk->private;
    + struct vm_area_struct *vma = walk->vma;
    +
    + /*
    + * Writing 1 to /proc/pid/clear_refs affects all pages.
    + * Writing 2 to /proc/pid/clear_refs only affects anonymous pages.
    + * Writing 3 to /proc/pid/clear_refs only affects file mapped pages.
    + * Writing 4 to /proc/pid/clear_refs affects all pages.
    + */
    + if (cp->type == CLEAR_REFS_ANON && vma->vm_file)
    + return 1;
    + if (cp->type == CLEAR_REFS_MAPPED && !vma->vm_file)
    + return 1;
    + if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
    + if (vma->vm_flags & VM_SOFTDIRTY)
    + vma->vm_flags &= ~VM_SOFTDIRTY;
    + }
    + return 0;
    +}
    +
    static ssize_t clear_refs_write(struct file *file, const char __user *buf,
    size_t count, loff_t *ppos)
    {
    @@ -822,38 +844,14 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
    };
    struct mm_walk clear_refs_walk = {
    .pmd_entry = clear_refs_pte_range,
    + .test_walk = clear_refs_test_walk,
    .mm = mm,
    .private = &cp,
    };
    down_read(&mm->mmap_sem);
    if (type == CLEAR_REFS_SOFT_DIRTY)
    mmu_notifier_invalidate_range_start(mm, 0, -1);
    - for (vma = mm->mmap; vma; vma = vma->vm_next) {
    - cp.vma = vma;
    - if (is_vm_hugetlb_page(vma))
    - continue;
    - /*
    - * Writing 1 to /proc/pid/clear_refs affects all pages.
    - *
    - * Writing 2 to /proc/pid/clear_refs only affects
    - * Anonymous pages.
    - *
    - * Writing 3 to /proc/pid/clear_refs only affects file
    - * mapped pages.
    - *
    - * Writing 4 to /proc/pid/clear_refs affects all pages.
    - */
    - if (type == CLEAR_REFS_ANON && vma->vm_file)
    - continue;
    - if (type == CLEAR_REFS_MAPPED && !vma->vm_file)
    - continue;
    - if (type == CLEAR_REFS_SOFT_DIRTY) {
    - if (vma->vm_flags & VM_SOFTDIRTY)
    - vma->vm_flags &= ~VM_SOFTDIRTY;
    - }
    - walk_page_range(vma->vm_start, vma->vm_end,
    - &clear_refs_walk);
    - }
    + walk_page_range(0, ~0UL, &clear_refs_walk);
    if (type == CLEAR_REFS_SOFT_DIRTY)
    mmu_notifier_invalidate_range_end(mm, 0, -1);
    flush_tlb_mm(mm);
    --
    1.9.3


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