[PATCH] sched: add debugging

These conditions should now be impossible, and we need to fix them if they
happen.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/sched.c b/kernel/sched.c
index 41e69b5ee652114cae7f859bf7d0df0438fcaee5..8b035a8b3c30284e1a2140e8a3a98fe5c6b0329d 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1942,15 +1942,7 @@ static int load_balance(int this_cpu, runqueue_t *this_rq,
                goto out_balanced;
        }
 
-       /*
-        * This should be "impossible", but since load
-        * balancing is inherently racy and statistical,
-        * it could happen in theory.
-        */
-       if (unlikely(busiest == this_rq)) {
-               WARN_ON(1);
-               goto out_balanced;
-       }
+       BUG_ON(busiest == this_rq);
 
        schedstat_add(sd, lb_imbalance[idle], imbalance);
 
@@ -2052,11 +2044,13 @@ static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
        }
 
        busiest = find_busiest_queue(group);
-       if (!busiest || busiest == this_rq) {
+       if (!busiest) {
                schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
                goto out_balanced;
        }
 
+       BUG_ON(busiest == this_rq);
+
        /* Attempt to move tasks */
        double_lock_balance(this_rq, busiest);