Currently, walk_page_range() call find_vma() every page table
walk iteration. but it's completely unnecessary if walk->hugetlb_entry
is unused. And we don't have to assume find_vma() is lightweight
operation. Thus this patch check walk->hugetlb_entry and avoid
find_vma() call if possible.
This patch also makes some cleanups. 1) remove ugly uninitialized_var()
and 2) #ifdef in function body.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
---
mm/pagewalk.c | 43 +++++++++++++++++++++++++++++++++++++------
1 files changed, 37 insertions(+), 6 deletions(-)
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 606bbb4..ee4ff87 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -126,7 +126,39 @@ static int walk_hugetlb_range(struct vm_area_struct *vma,
return 0;
}
-#endif
+
+static struct vm_area_struct* hugetlb_vma(unsigned long addr, struct mm_walk *walk)
+{
+ struct vm_area_struct *vma;
+
+ /* We don't need vma lookup at all. */
+ if (!walk->hugetlb_entry)
+ return NULL;
+
+ VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem));
+ vma = find_vma(walk->mm, addr);
+ if (vma && vma->vm_start <= addr && is_vm_hugetlb_page(vma))
+ return vma;
+
+ return NULL;
+}
+
+#else /* CONFIG_HUGETLB_PAGE */
+static struct vm_area_struct* hugetlb_vma(unsigned long addr, struct mm_walk *walk)
+{
+ return NULL;
+}
+
+static int walk_hugetlb_range(struct vm_area_struct *vma,
+ unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
+{
+ return 0;
+}
+
+#endif /* CONFIG_HUGETLB_PAGE */
+
+
/**
* walk_page_range - walk a memory map's page tables with a callback
@@ -165,18 +197,17 @@ int walk_page_range(unsigned long addr, unsigned long end,
pgd = pgd_offset(walk->mm, addr);
do {
- struct vm_area_struct *uninitialized_var(vma);
+ struct vm_area_struct *vma;
next = pgd_addr_end(addr, end);
-#ifdef CONFIG_HUGETLB_PAGE
/*
* handle hugetlb vma individually because pagetable walk for
* the hugetlb page is dependent on the architecture and
* we can't handled it in the same manner as non-huge pages.
*/
- vma = find_vma(walk->mm, addr);
- if (vma && vma->vm_start <= addr && is_vm_hugetlb_page(vma)) {
+ vma = hugetlb_vma(addr, walk);
+ if (vma) {
if (vma->vm_end < next)
next = vma->vm_end;
/*
@@ -189,7 +220,7 @@ int walk_page_range(unsigned long addr, unsigned long end,
pgd = pgd_offset(walk->mm, next);
continue;
}
-#endif
+
if (pgd_none_or_clear_bad(pgd)) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, walk);
--
1.7.3.1
--
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