[tip:sched/urgent] sched: Fix hotplug hang

From: tip-bot for Peter Zijlstra
Date: Sun Dec 20 2009 - 17:34:55 EST

Commit-ID: 70f1120527797adb31c68bdc6f1b45e182c342c7
Gitweb: http://git.kernel.org/tip/70f1120527797adb31c68bdc6f1b45e182c342c7
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Sun, 20 Dec 2009 17:36:27 +0100
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Sun, 20 Dec 2009 23:31:23 +0100

sched: Fix hotplug hang

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@xxxxxxxxxx>
Reported-by: Jens Axboe <jens.axboe@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Tested-by: Jens Axboe <jens.axboe@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
LKML-Reference: <1261326987.4314.24.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
kernel/sched.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 7ffde2a..87f1f47 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2346,7 +2346,7 @@ 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;
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