On Fri, Sep 21, 2012 at 06:08:59PM +0000, Paul Walmsley wrote: > cc Frederic Weisbecker - context is here: > > http://marc.info/?l=linux-kernel&m=134749030206016&w=2 > > On Thu, 20 Sep 2012, Paul E. McKenney wrote: > > > Fair point. I am wondering whether there is some path into the idle > > loop that somehow avoids telling RCU that the CPU has in face entered > > idle. There needs to be an rcu_idle_enter() call on the way to idle, > > otherwise RCU CPU stall warnings are expected behavior. > > As far as I know, our only idle entry point is in > arch/arm/common/process.c:cpu_idle(). In mainline, this is arch/arm/kernel/process.c, correct? > Looking at the x86 idle entry, they call rcu_idle_{enter,exit}() inside > {stop,start}_critical_timings(). Making that change here didn't help. The reason x86 does this is that they have idle notifiers deeper in the idle loop that use RCU read-side critical sections. So this was an expected result. > Also tried commenting out the code from the stop_critical_timings() call > to the WARN_ON(irqs_disabled()), and adding a local_irq_enable(). That > also didn't help, which suggests that the problem is not caused by the > OMAP-specific PM idle code. I must admit that you make a convincing case here. Though it does leave me wondering what is different about Panda (and MX28, IIRC). I may take your advice of remote access to a Panda board, though that is likely to take a bit of time due to timezones. Regardless of the underlying issue here, I clearly need to make the stall-warning messages do a better job of printing out needed information. Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
