On Thu, Jun 06, 2013 at 02:29:49PM -0700, gree...@candelatech.com wrote: > From: Ben Greear <gree...@candelatech.com> > > The stop machine logic can lock up if all but one of > the migration threads make it through the disable-irq > step and the one remaining thread gets stuck in > __do_softirq. The reason __do_softirq can hang is > that it has a bail-out based on jiffies timeout, but > in the lockup case, jiffies itself is not incremented. > > To work around this, re-add the max_restart counter in __do_irq > and stop processing irqs after 10 restarts. > > Thanks to Tejun Heo and Rusty Russell and others for > helping me track this down. > > This was introduced in 3.9 by commit: c10d73671ad30f5469 > (softirq: reduce latencies). > > It may be worth looking into ath9k to see if it has issues with > it's irq handler at a later date. > > The hang stack traces look something like this: ... > Signed-off-by: Ben Greear <gree...@candelatech.com>
Acked-by: Tejun Heo <t...@kernel.org> Linus, while this doesn't fix the root cause of the problem - softirq runaway - I still think this is a worthwhile protection to have. Ben is in the process of finding out why the softirq runaway happens in the first place. We probably want to add Cc: sta...@vger.kernel.org tag. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
