Messages in this thread | | | Subject | Re: [rfc][patch] mm: lockdep page lock | From | Peter Zijlstra <> | Date | Fri, 26 Mar 2010 07:54:07 +0100 |
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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.
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