On Fri, Mar 17, 2017 at 02:02:53PM +0000, David Woodhouse wrote: > On Fri, 2017-03-17 at 11:43 +0000, David Woodhouse wrote: > > > > Is this one going to be be my fault too? > > Looks like it isn't my fault. In ipi_cpu_crash_stop() we don't modify > the online mask. Which is reasonable enough if we want to preserve its > original contents from before the crash, but it does make that > WARN_ON() in machine_kexec() a false positive. I'd say it's not so much a false positive, but rather an uninformative message. Some warning here is completely appropriate. Even if the CPUs are stopped in the kernel, there are a number of cases where the HW can corrupt system state in the background. We can certainly log a better message, e.g. bool kdump = (image == kexec_crash_image); bool stuck_cpus = cpus_are_stuck_in_kernel() || num_online_cpus() > 1; BUG_ON(stuck_cpus && !kdump); WARN(stuck_cpus, "Unable to offline CPUs, kdump will be unreliable.\n"); Thanks, Mark.
