vmalloc: annotate lock context change on s_start/stop()

s_start() and s_stop() grab/release vmlist_lock but were missing proper
annotations.  Add them.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/vmalloc.c

@@ -2350,6 +2350,7 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
 
 #ifdef CONFIG_PROC_FS
 static void *s_start(struct seq_file *m, loff_t *pos)
+	__acquires(&vmlist_lock)
 {
 	loff_t n = *pos;
 	struct vm_struct *v;
@@ -2376,6 +2377,7 @@ static void *s_next(struct seq_file *m, void *p, loff_t *pos)
 }
 
 static void s_stop(struct seq_file *m, void *p)
+	__releases(&vmlist_lock)
 {
 	read_unlock(&vmlist_lock);
 }