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Subject[PATCH 09/10] mm: pagewalk: use new locked walker for /proc/pid/smaps
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From: Dave Hansen <dave.hansen@linux.intel.com>

The diffstat tells the story here. Using the new walker function
greatly simplifies the code. One side-effect here is that we'll
call cond_resched() more often than we did before. It used to be
called once per pte page, but now it's called on every pte.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
---

b/fs/proc/task_mmu.c | 27 +++++----------------------
1 file changed, 5 insertions(+), 22 deletions(-)

diff -puN fs/proc/task_mmu.c~mm-pagewalk-use-locked-walker-smaps fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~mm-pagewalk-use-locked-walker-smaps 2014-06-02 14:20:21.247895019 -0700
+++ b/fs/proc/task_mmu.c 2014-06-02 14:20:21.251895198 -0700
@@ -490,32 +490,15 @@ static void smaps_pte_entry(pte_t ptent,
}
}

-static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
+static int smaps_single_locked(pte_t *pte, unsigned long addr, unsigned long size,
struct mm_walk *walk)
{
struct mem_size_stats *mss = walk->private;
- struct vm_area_struct *vma = walk->vma;
- pte_t *pte;
- spinlock_t *ptl;
-
- if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
- smaps_pte_entry(*(pte_t *)pmd, addr, HPAGE_PMD_SIZE, walk);
- spin_unlock(ptl);
+
+ if (size == HPAGE_PMD_SIZE)
mss->anonymous_thp += HPAGE_PMD_SIZE;
- return 0;
- }

- if (pmd_trans_unstable(pmd))
- return 0;
- /*
- * The mmap_sem held all the way back in m_start() is what
- * keeps khugepaged out of here and from collapsing things
- * in here.
- */
- pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
- for (; addr != end; pte++, addr += PAGE_SIZE)
- smaps_pte_entry(*pte, addr, PAGE_SIZE, walk);
- pte_unmap_unlock(pte - 1, ptl);
+ smaps_pte_entry(*pte, addr, size, walk);
cond_resched();
return 0;
}
@@ -581,7 +564,7 @@ static int show_smap(struct seq_file *m,
struct vm_area_struct *vma = v;
struct mem_size_stats mss;
struct mm_walk smaps_walk = {
- .pmd_entry = smaps_pte_range,
+ .locked_single_entry = smaps_single_locked,
.mm = vma->vm_mm,
.private = &mss,
};
_

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