[PATCH] mm/vmalloc.c: Remove always-true conditional in vmap_init_free_space

[Pengfei Li]

When unsigned long variables are subtracted from one another,
the result is always non-negative.

The vmap_area_list is sorted by address.

So the following two conditions are always true.

1) if (busy->va_start - vmap_start > 0)
2) if (vmap_end - vmap_start > 0)

Just remove them.

Signed-off-by: Pengfei Li <lpf.vec...@gmail.com>
---
 mm/vmalloc.c | 32 +++++++++++++-------------------
 1 file changed, 13 insertions(+), 19 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 0f76cca32a1c..c7bdbdc18472 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1810,31 +1810,25 @@ static void vmap_init_free_space(void)
         *  |<--------------------------------->|
         */
        list_for_each_entry(busy, &vmap_area_list, list) {
-               if (busy->va_start - vmap_start > 0) {
-                       free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
-                       if (!WARN_ON_ONCE(!free)) {
-                               free->va_start = vmap_start;
-                               free->va_end = busy->va_start;
-
-                               insert_vmap_area_augment(free, NULL,
-                                       &free_vmap_area_root,
-                                               &free_vmap_area_list);
-                       }
-               }
-
-               vmap_start = busy->va_end;
-       }
-
-       if (vmap_end - vmap_start > 0) {
                free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
                if (!WARN_ON_ONCE(!free)) {
                        free->va_start = vmap_start;
-                       free->va_end = vmap_end;
+                       free->va_end = busy->va_start;
 
                        insert_vmap_area_augment(free, NULL,
-                               &free_vmap_area_root,
-                                       &free_vmap_area_list);
+                               &free_vmap_area_root, &free_vmap_area_list);
                }
+
+               vmap_start = busy->va_end;
+       }
+
+       free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
+       if (!WARN_ON_ONCE(!free)) {
+               free->va_start = vmap_start;
+               free->va_end = vmap_end;
+
+               insert_vmap_area_augment(free, NULL,
+                       &free_vmap_area_root, &free_vmap_area_list);
        }
 }
 
-- 
2.21.0