On Sat, Nov 09, 2013 at 04:13:56PM +0100, Peter Zijlstra wrote: > On Sat, Nov 09, 2013 at 03:52:59PM +0100, Frederic Weisbecker wrote: > > So, an idea of what may be happening: an event overflows while FASYNC flag > > is set so it triggers an irq work > > to send the signal (kill_fasync). > > After the irq work triggers, it generates an irq_work_exit event, which in > > turn overflows and, > > if it has FASYNC, triggers a new irq work. The irq work triggers and > > generates an irq work exit event which > > has FASYNC flag, etc... > > > > Looks like a nice way to deadlock with an infinite loop of irq work. > > > Yep, exactly, see the email I just send.
In fact, raising an irq work from an irq work should simply be prohibited. That's not a sane behaviour. It's natural for async stuffs that have reasonable delays between each pass allow re-enqueuing, like workqueue or rcu callbacks, or timers. But with irq work that doesn't look right, expect for lazy irq works though. But lets just not allow it at all :) -- 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/
