On Tue, 2022-05-10 at 09:52 -0700, Josh Poimboeuf wrote: > On Tue, May 10, 2022 at 04:07:42PM +0000, Rik van Riel wrote: > > > > > 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... > > > > 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. > The systems where we are seeing problems do not, as far as I know, throw softlockup errors, so the kworker threads that fail to transition to the new KLP version are sleeping and getting scheduled out at times. A KLP transition preempt notifier would help those kernel threads transition to the new KLP version at any time they reschedule. How much it will help is hard to predict, but I should be able to get results from a fairly large sample size of systems within a few weeks :)
