Re: CPU hotplug broken in 2.6.8-rc2 ?

[Nathan Lynch <nathanl@austin.ibm.com>]

On Mon, 2004-08-02 at 14:38, Nathan Lynch wrote:
> Could you try on 2.6.8-rc2-mm2 along with this patch?  Vatsa had a patch
> go in that should prevent the crash you are seeing -- the patch below is
> needed to prevent the same crash in the offline case.  This check used
> to be in load_balance and some other scheduler functions, iirc; does
> anyone know why they were removed?

Er, I meant to put the check in rebalance_tick, not load_balance.

However, after a few minutes with this, I hit the BUG_ON in the CPU_DEAD
case in migration_call; not sure whether this is a separate issue.

Nathan

---

diff -puN kernel/sched.c~check-for-cpu-offline-in-rebalance_tick kernel/sched.c
--- 2.6.8-rc2-mm2/kernel/sched.c~check-for-cpu-offline-in-rebalance_tick	2004-08-02 15:18:24.000000000 -0500
+++ 2.6.8-rc2-mm2-nathanl/kernel/sched.c	2004-08-02 15:18:47.000000000 -0500
@@ -1616,6 +1616,9 @@ static void rebalance_tick(int this_cpu,
 	unsigned long j = jiffies + CPU_OFFSET(this_cpu);
 	struct sched_domain *sd;
 
+	if (cpu_is_offline(this_cpu))
+		return;
+
 	/* Update our load */
 	old_load = this_rq->cpu_load;
 	this_load = this_rq->nr_running * SCHED_LOAD_SCALE;

_