pagemap: use walk->vma instead of calling find_vma()
Page table walker has the information of the current vma in mm_walk, so we
don't have to call find_vma() in each pagemap_(pte|hugetlb)_range() call
any longer. Currently pagemap_pte_range() does vma loop itself, so this
patch reduces many lines of code.
NULL-vma check is omitted because we assume that we never run these
callbacks on any address outside vma. And even if it were broken, NULL
pointer dereference would be detected, so we can get enough information
for debugging.
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.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: Kirill A. Shutemov <kirill.shutemov@linux.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 bed0834..4206706 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1047,15 +1047,13 @@
static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
- struct vm_area_struct *vma;
+ struct vm_area_struct *vma = walk->vma;
struct pagemapread *pm = walk->private;
spinlock_t *ptl;
pte_t *pte, *orig_pte;
int err = 0;
- /* find the first VMA at or above 'addr' */
- vma = find_vma(walk->mm, addr);
- if (vma && pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+ if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
int pmd_flags2;
if ((vma->vm_flags & VM_SOFTDIRTY) || pmd_soft_dirty(*pmd))
@@ -1081,55 +1079,20 @@
if (pmd_trans_unstable(pmd))
return 0;
- while (1) {
- /* End of address space hole, which we mark as non-present. */
- unsigned long hole_end;
+ /*
+ * We can assume that @vma always points to a valid one and @end never
+ * goes beyond vma->vm_end.
+ */
+ orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+ for (; addr < end; pte++, addr += PAGE_SIZE) {
+ pagemap_entry_t pme;
- if (vma)
- hole_end = min(end, vma->vm_start);
- else
- hole_end = end;
-
- for (; addr < hole_end; addr += PAGE_SIZE) {
- pagemap_entry_t pme = make_pme(PM_NOT_PRESENT(pm->v2));
-
- err = add_to_pagemap(addr, &pme, pm);
- if (err)
- return err;
- }
-
- if (!vma || vma->vm_start >= end)
- break;
- /*
- * We can't possibly be in a hugetlb VMA. In general,
- * for a mm_walk with a pmd_entry and a hugetlb_entry,
- * the pmd_entry can only be called on addresses in a
- * hugetlb if the walk starts in a non-hugetlb VMA and
- * spans a hugepage VMA. Since pagemap_read walks are
- * PMD-sized and PMD-aligned, this will never be true.
- */
- BUG_ON(is_vm_hugetlb_page(vma));
-
- /* Addresses in the VMA. */
- orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
- for (; addr < min(end, vma->vm_end); pte++, addr += PAGE_SIZE) {
- pagemap_entry_t pme;
-
- pte_to_pagemap_entry(&pme, pm, vma, addr, *pte);
- err = add_to_pagemap(addr, &pme, pm);
- if (err)
- break;
- }
- pte_unmap_unlock(orig_pte, ptl);
-
+ pte_to_pagemap_entry(&pme, pm, vma, addr, *pte);
+ err = add_to_pagemap(addr, &pme, pm);
if (err)
- return err;
-
- if (addr == end)
break;
-
- vma = find_vma(walk->mm, addr);
}
+ pte_unmap_unlock(orig_pte, ptl);
cond_resched();
@@ -1155,15 +1118,12 @@
struct mm_walk *walk)
{
struct pagemapread *pm = walk->private;
- struct vm_area_struct *vma;
+ struct vm_area_struct *vma = walk->vma;
int err = 0;
int flags2;
pagemap_entry_t pme;
- vma = find_vma(walk->mm, addr);
- WARN_ON_ONCE(!vma);
-
- if (vma && (vma->vm_flags & VM_SOFTDIRTY))
+ if (vma->vm_flags & VM_SOFTDIRTY)
flags2 = __PM_SOFT_DIRTY;
else
flags2 = 0;