On Tue, May 10, 2022 at 04:07:42PM +0000, Rik van Riel wrote: > On Tue, 2022-05-10 at 17:44 +0200, Petr Mladek wrote: > > On Tue 2022-05-10 13:33:13, Rik van Riel wrote: > > > On Tue, 2022-05-10 at 09:56 +0200, Petr Mladek wrote: > > > > > > > > I think the best approach for us might be to just track what > > > is causing the transition failures, and send in trivial patches > > > to make the outer loop in such kernel threads do the same KLP > > > transition the idle task already does. > > > > I am afraid that is a way to hell. We might end up in doing > > really crazy things if we want to complete the transition > > in one minute. > > > Now I wonder if we could just hook up a preempt notifier > for kernel live patches. All the distro kernels already > need the preempt notifier for KVM, anyway... > > Is it crazy? Maybe a little. > > Is it self contained, and something that could be done > without inserting any extra code into a hot path while > not in the middle of a KLP transition? Yes. > > I'd be happy to come up with a patch that does that, > unless anybody has good reasons I should not :) I wouldn't be opposed to that, but how does it solve this problem? If as Peter said cond_resched() can be a NOP, then preemption would have to be from an interrupt, in which case frame pointers aren't reliable. -- Josh
