From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Fri, 26 Jul 2013 11:49:08 +0100 Subject: [PATCH] ARM: kexec: offline non panic CPUs on Kdump panic In-Reply-To: <1374817287-27952-1-git-send-email-vijay.kilari@gmail.com> References: <1374817287-27952-1-git-send-email-vijay.kilari@gmail.com> Message-ID: <20130726104908.GC17886@mudshark.cambridge.arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org [Adding Stephen Warren since he has been working in this area] On Fri, Jul 26, 2013 at 06:41:27AM +0100, vijay.kilari at gmail.com wrote: > From: Vijaya Kumar K > > In case of normal kexec kernel load, all cpu's are offlined > before calling machine_kexec() under kernel_kexec() function. > But in case crash panic cpus are relaxed in > machine_crash_nonpanic_core() SMP function but not offlined. > > When crash kernel is loaded with kexec and on panic trigger > machine_kexec() checks for number of cpus online. > If more than one cpu is online machine_kexec() fails to load > with below error > > kexec: error: multiple CPUs still online > > In machine_crash_nonpanic_core() SMP function, offline CPU > before cpu_relax > > Signed-off-by: Vijaya Kumar K > --- > arch/arm/kernel/machine_kexec.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c > index 4fb074c..163b160 100644 > --- a/arch/arm/kernel/machine_kexec.c > +++ b/arch/arm/kernel/machine_kexec.c > @@ -73,6 +73,7 @@ void machine_crash_nonpanic_core(void *unused) > crash_save_cpu(®s, smp_processor_id()); > flush_cache_all(); > > + set_cpu_online(smp_processor_id(), false); > atomic_dec(&waiting_for_crash_ipi); > while (1) > cpu_relax(); Ok, I guess this will work since the new kernel is loaded somewhere higher in memory and the crashed kernel will stick around, so the non-crashing CPUs can sit around spinning. Will