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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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