mm/khugepaged: optimize collapse_pte_mapped_thp() by using vma_lookup()

vma_lookup() will walk the vma tree once and not continue to look for the
next vma.  Since the exact vma is checked below, this is a more optimal
way of searching.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Tested-by: Yu Zhao <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Howells <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: "Matthew Wilcox (Oracle)" <[email protected]>
Cc: SeongJae Park <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: howlett

mm/khugepaged.c

@@ -1389,7 +1389,7 @@ static void collapse_and_free_pmd(struct mm_struct *mm, struct vm_area_struct *v
 void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
 {
 	unsigned long haddr = addr & HPAGE_PMD_MASK;
-	struct vm_area_struct *vma = find_vma(mm, haddr);
+	struct vm_area_struct *vma = vma_lookup(mm, haddr);
 	struct page *hpage;
 	pte_t *start_pte, *pte;
 	pmd_t *pmd;