On Fri, 2010-03-26 at 03:18 +0000, Jamie Lokier wrote: > Peter Zijlstra wrote: > > On Tue, 2010-03-16 at 13:21 +1100, Nick Piggin wrote: > > > > > > > > > Agreed (btw. Peter is there any way to turn lock debugging back on? > > > it's annoying when cpufreq hotplug code or something early breaks and > > > you have to reboot in order to do any testing). > > > > Not really, the only way to do that is to get the full system back into > > a known (zero) lock state and then fully reset the lockdep state. > > How about: Set a variable nr_pending = number of CPUs, run a task on > each CPU which disables interrupts, atomically decrements nr_pending > and then spins waiting for it to become negative (raw, not counted in > lockdep), and whichever one takes it to zero, that task knows there > are no locks held, and can reset the lockdep state. Then sets it to > -1 to wake everyone. Nope, won't work, you can easily preempt a lock holder. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>