sched: Fix hotplug hang

commit 70f1120527797adb31c68bdc6f1b45e182c342c7 upstream

The hot-unplug kstopmachine usage does a wakeup after
deactivating the cpu, hence we cannot use cpu_active()
here but must rely on the good olde online.

Reported-by: Sachin Sant <sachinp@in.ibm.com>
Reported-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
LKML-Reference: <1261326987.4314.24.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/kernel/sched.c b/kernel/sched.c
index 86f2a6b61da5c2ee1fb7b667ba7a7a537781f4a0..b8ece01d43448842790889d0c5c24f541b1260e2 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2376,7 +2376,7 @@ int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags)
         *   not worry about this generic constraint ]
         */
        if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) ||
-                    !cpu_active(cpu)))
+                    !cpu_online(cpu)))
                cpu = select_fallback_rq(task_cpu(p), p);
 
        return cpu;