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>

1 files changed, 4 insertions, 0 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index afe3e1ff919b..62f9fada4d6d 100644
--- 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);