mm, vmalloc: use well-defined find_last_bit() func

Our intention in here is to find last_bit within the region to flush.
There is well-defined function, find_last_bit() for this purpose and its
performance may be slightly better than current implementation.  So change
it.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 9 deletions

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d23c43258727..93d3182c3300 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1016,15 +1016,16 @@ void vm_unmap_aliases(void)
 
                 rcu_read_lock();
                 list_for_each_entry_rcu(vb, &vbq->free, free_list) {
-                        int i;
+                        int i, j;
 
                         spin_lock(&vb->lock);
                         i = find_first_bit(vb->dirty_map, VMAP_BBMAP_BITS);
-                        while (i < VMAP_BBMAP_BITS) {
+                        if (i < VMAP_BBMAP_BITS) {
                                 unsigned long s, e;
-                                int j;
-                                j = find_next_zero_bit(vb->dirty_map,
-                                        VMAP_BBMAP_BITS, i);
+
+                                j = find_last_bit(vb->dirty_map,
+                                                        VMAP_BBMAP_BITS);
+                                j = j + 1; /* need exclusive index */
 
                                 s = vb->va->va_start + (i << PAGE_SHIFT);
                                 e = vb->va->va_start + (j << PAGE_SHIFT);
@@ -1034,10 +1035,6 @@ void vm_unmap_aliases(void)
                                         start = s;
                                 if (e > end)
                                         end = e;
-
-                                i = j;
-                                i = find_next_bit(vb->dirty_map,
-                                                        VMAP_BBMAP_BITS, i);
                         }
                         spin_unlock(&vb->lock);
                 }