Messages in this thread | | | From | Hari Bathini <> | Subject | Re: [PATCH] powerpc: on crash, kexec'ed kernel needs all CPUs are online | Date | Wed, 4 Nov 2015 18:04:18 +0530 |
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On 10/16/2015 12:30 AM, Laurent Vivier wrote: > On kexec, all secondary offline CPUs are onlined before > starting the new kernel, this is not done in the case of kdump. > > If kdump is configured and a kernel crash occurs whereas > some secondaries CPUs are offline (SMT=off), > the new kernel is not able to start them and displays some > "Processor X is stuck.". > > Starting with POWER8, subcore logic relies on all threads of > core being booted. So, on startup kernel tries to start all > threads, and asks OPAL (or RTAS) to start all CPUs (including > threads). If a CPU has been offlined by the previous kernel, > it has not been returned to OPAL, and thus OPAL cannot restart > it: this CPU has been lost... > > Signed-off-by: Laurent Vivier<lvivier@redhat.com>
Hi Laurent,
Sorry for jumping too late into this. Are you seeing this issue even with the below patches:
pseries: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c1caae3de46a072d0855729aed6e793e536a4a55
opal/powernv: https://github.com/open-power/skiboot/commit/9ee56b5
Thanks Hari
> --- > arch/powerpc/kernel/crash.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/arch/powerpc/kernel/crash.c b/arch/powerpc/kernel/crash.c > index 51dbace..3ca9452 100644 > --- a/arch/powerpc/kernel/crash.c > +++ b/arch/powerpc/kernel/crash.c > @@ -19,6 +19,7 @@ > #include <linux/delay.h> > #include <linux/irq.h> > #include <linux/types.h> > +#include <linux/cpu.h> > > #include <asm/processor.h> > #include <asm/machdep.h> > @@ -299,11 +300,30 @@ int crash_shutdown_unregister(crash_shutdown_t handler) > } > EXPORT_SYMBOL(crash_shutdown_unregister); > > +/* > + * The next kernel will try to start all secondary CPUs and if > + * there are not online it will fail to start them. > + * > + */ > +static void wake_offline_cpus(void) > +{ > + int cpu = 0; > + > + for_each_present_cpu(cpu) { > + if (!cpu_online(cpu)) { > + pr_info("kexec: Waking offline cpu %d.\n", cpu); > + cpu_up(cpu); > + } > + } > +} > + > void default_machine_crash_shutdown(struct pt_regs *regs) > { > unsigned int i; > int (*old_handler)(struct pt_regs *regs); > > + wake_offline_cpus(); > + > /* > * This function is only called after the system > * has panicked or is otherwise in a critical state.
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