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SubjectRe: CPU hotplug and IRQ affinity with 2.6.24-rt1
>>> On Tue, Feb 5, 2008 at 11:59 AM, in message
<20080205165936.GA18613@dwalker1.mvista.com>, Daniel Walker
<dwalker@dwalker1.mvista.com> wrote:
> On Mon, Feb 04, 2008 at 10:02:12PM -0700, Gregory Haskins wrote:
>> >>> On Mon, Feb 4, 2008 at 9:51 PM, in message
>> <20080205025144.GA31774@dwalker1.mvista.com>, Daniel Walker
>> <dwalker@dwalker1.mvista.com> wrote:
>> > I get the following when I tried it,
>> >
>> > BUG: sleeping function called from invalid context bash(5126) at
>> > kernel/rtmutex.c:638
>> > in_atomic():1 [00000001], irqs_disabled():1
>>
>> Hi Daniel,
>> Can you try this patch and let me know if it fixes your problem?
>>
>> -----------------------
>>
>> use rcu for root-domain kfree
>>
>> Signed-off-by: Gregory Haskins <ghaskins@novell.com>
>>
>> diff --git a/kernel/sched.c b/kernel/sched.c
>> index e6ad493..77e86c1 100644
>> --- a/kernel/sched.c
>> +++ b/kernel/sched.c
>> @@ -339,6 +339,7 @@ struct root_domain {
>> atomic_t refcount;
>> cpumask_t span;
>> cpumask_t online;
>> + struct rcu_head rcu;
>>
>> /*
>> * The "RT overload" flag: it gets set if a CPU has more than
>> @@ -6222,6 +6223,12 @@ sd_parent_degenerate(struct sched_domain *sd, struct
> sched_domain *parent)
>> return 1;
>> }
>>
>> +/* rcu callback to free a root-domain */
>> +static void rq_free_root(struct rcu_head *rcu)
>> +{
>> + kfree(container_of(rcu, struct root_domain, rcu));
>> +}
>> +
>
> I looked at the code a bit, and I'm not sure you need this complexity..
> Once you have replace the old_rq, there is no reason it needs to
> protection of the run queue spinlock .. So you could just move the kfree
> down below the spin_unlock_irqrestore() ..

Indeed. When I looked last night at the stack, I thought the in_atomic was coming from further up in the trace. I see the issue now, thanks Daniel. (Anyone have a spare brown bag?)

-Greg

>
> Daniel
> -
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