mm: hugetlb: bail out unmapping after serving reference page

When unmapping a given VM range, we could bail out if a reference page is
supplied and is unmapped, which is a minor optimization.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index afe3e1ff919b150c33344a2acfa9f80d8d54b765..62f9fada4d6de9f912cad9bfacf6cf84098914f0 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2280,6 +2280,10 @@ void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
                if (pte_dirty(pte))
                        set_page_dirty(page);
                list_add(&page->lru, &page_list);
+
+               /* Bail out after unmapping reference page if supplied */
+               if (ref_page)
+                       break;
        }
        flush_tlb_range(vma, start, end);
        spin_unlock(&mm->page_table_lock);