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SubjectRe: [PATCH] x86: make reboot task only run on the appropriate processor
On 11/05/13 at 03:28pm, Vivek Goyal wrote:
> On Tue, Nov 05, 2013 at 05:16:07PM +0800, Baoquan He wrote:
> > Currently system always reboot after below message when execute "kexec -e".
> >
> > [ 0.572119] smpboot: Booting Node 0, Processors # 1 OK
> >
>
> So is it same problem were we reboot on non-boot cpu and sending INIT
> to boot cpu in second kernel brings down the machine?

I was wrong, they are the same problem. With multiple CPUs, by setting
affinity to execute crash or kexec on CPUn(n!==0), they all reboot after
the same message as below and then reboot through BIOS. It should be the
BSP got a INIT IPI message and make system hang.

[ 0.572119] smpboot: Booting Node 0, Processors # 1 OK

>
> I think for x86, it makes sense to reboot on boot cpu.
>
> Thanks
> Vivek
>
> > In commit 1b3a5d02ee070c8f9943333b9b6370f486601e0f, reboot= handling was
> > moved to kerne/reboot.c. However, the code to migrate current thread to
> > reboot cpu was removed. That cause this incorrect kexec behavior.
> >
> > Now add that code block back.
> >
> > Reported-by: Matthew Whitehead <mwhitehe@redhat.com>
> > Reported-by: Dave Young <dyoung@redhat.com>
> > Tested-by: WANG Chao <chaowang@redhat.com>
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > ---
> > arch/x86/kernel/reboot.c | 15 +++++++++++++++
> > 1 file changed, 15 insertions(+)
> >
> > diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
> > index 7e920bf..3049de9 100644
> > --- a/arch/x86/kernel/reboot.c
> > +++ b/arch/x86/kernel/reboot.c
> > @@ -551,6 +551,21 @@ void native_machine_shutdown(void)
> > {
> > /* Stop the cpus and apics */
> > #ifdef CONFIG_SMP
> > + /* The boot cpu is always logical cpu 0 */
> > + int reboot_cpu_id = 0;
> > +
> > + /* See if there has been given a command line override */
> > + if ((reboot_cpu != -1) && (reboot_cpu < nr_cpu_ids) &&
> > + cpu_online(reboot_cpu))
> > + reboot_cpu_id = reboot_cpu;
> > +
> > + /* Make certain the cpu I'm about to reboot on is online */
> > + if (!cpu_online(reboot_cpu_id))
> > + reboot_cpu_id = smp_processor_id();
> > +
> > + /* Make certain I only run on the appropriate processor */
> > + set_cpus_allowed_ptr(current, cpumask_of(reboot_cpu_id));
> > +
> > /*
> > * Stop all of the others. Also disable the local irq to
> > * not receive the per-cpu timer interrupt which may trigger
> > --
> > 1.8.3.1
>
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec


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