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>

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d23c432..93d3182 100644 (file)
--- 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);
                }