On Tue, Aug 05, 2008 at 09:25:01AM +0200, Peter Zijlstra wrote: > On Mon, 2008-08-04 at 22:52 +0200, John Kacur wrote: > > Even after applying some fixes posted by Chirag and Peter Z, I'm still > > getting some messages in my log like this > > > BUG: sleeping function called from invalid context swapper(0) at > > kernel/rtmutex.c:743 > > in_atomic():1 [00000001], irqs_disabled():1 > > Pid: 0, comm: swapper Tainted: G W 2.6.26.1-rt1.jk #2 > > > > Call Trace: > > [<ffffffff802305d3>] __might_sleep+0x12d/0x132 > > [<ffffffff8046cdbe>] __rt_spin_lock+0x34/0x7d > > [<ffffffff8046ce15>] rt_spin_lock+0xe/0x10 > > [<ffffffff802532e5>] pm_qos_requirement+0x1f/0x3c > > [<ffffffff803e1b7f>] menu_select+0x7b/0x9c > > [<ffffffff8020b1be>] ? default_idle+0x0/0x5a > > [<ffffffff8020b1be>] ? default_idle+0x0/0x5a > > [<ffffffff803e0b4b>] cpuidle_idle_call+0x68/0xd8 > > [<ffffffff803e0ae3>] ? cpuidle_idle_call+0x0/0xd8 > > [<ffffffff8020b1be>] ? default_idle+0x0/0x5a > > [<ffffffff8020b333>] cpu_idle+0xb2/0x12d > > [<ffffffff80466af0>] start_secondary+0x186/0x18b > > > > --------------------------- > > | preempt count: 00000001 ] > > | 1-level deep critical section nesting: > > ---------------------------------------- > > ... [<ffffffff8020b39c>] .... cpu_idle+0x11b/0x12d > > ......[<ffffffff80466af0>] .. ( <= start_secondary+0x186/0x18b) > > > > The following simple patch makes the messages disappear - however, > > there may be a better more fine grained solution, but the problem is > > also that all the functions are designed to use the same lock. > > Hmm, I think you're right - its called from the idle routine so we can't > go about sleeping there. > > The only trouble I have is with kernel/pm_qos_params.c:update_target()'s > use of this lock - that is decidedly not O(1). > > Mark, would it be possible to split that lock in two, one lock > protecting pm_qos_array[], and one lock protecting the > requirements.list ? very likely, but I'm not sure how it will help. the fine grain locking I had initially worked out on pm_qos was to have a lock per pm_qos_object, that would be used for accessing the requirement_list and the target_value. But that isn't what you are asking about is it? Is what you want is a pm_qos_requirements_list_lock and a pm_qos_target_value_lock, for each pm_qos_object instance? I guess it wold work but besides giving the code spinlock diarrhea would it really help solve the issue you are seeing? --mgross > [ NOTE: this is the -rt kernel we're talking about ] > > > Signed-off-by: John Kacur <jkacur at gmail dot com> > > > > Index: linux-2.6.26.1-jk-rt1/kernel/pm_qos_params.c > > =================================================================== > > --- linux-2.6.26.1-jk-rt1.orig/kernel/pm_qos_params.c > > +++ linux-2.6.26.1-jk-rt1/kernel/pm_qos_params.c > > @@ -110,7 +110,7 @@ static struct pm_qos_object *pm_qos_arra > > &network_throughput_pm_qos > > }; > > > > -static DEFINE_SPINLOCK(pm_qos_lock); > > +static DEFINE_RAW_SPINLOCK(pm_qos_lock); > > > > static ssize_t pm_qos_power_write(struct file *filp, const char > > __user *buf, > > size_t count, loff_t *f_pos); > > -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
