clear_refs: remove clear_refs_private->vma and introduce clear_refs_test_walk()

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.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 7342539..bed0834 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -736,7 +736,6 @@ enum clear_refs_types {
 };
 
 struct clear_refs_private {
-       struct vm_area_struct *vma;
        enum clear_refs_types type;
 };
 
@@ -767,7 +766,7 @@ 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;
@@ -801,6 +800,25 @@ 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;
+       return 0;
+}
+
 static ssize_t clear_refs_write(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
 {
@@ -841,6 +859,7 @@ 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,
                };
@@ -860,28 +879,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
                        }
                        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;
-                       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);