| Message ID | 1541071249-15660-1-git-send-email-wangyufen@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ARM:kexec:offline panic_smp_self_stop CPU | expand |
On Thu, Nov 01, 2018 at 07:20:49PM +0800, Wang Yufen wrote: > From: Yufen Wang <wangyufen@huawei.com> > > In case panic() and panic() called at the same time on different CPUS. > For example: > CPU 0: > panic() > __crash_kexec > machine_crash_shutdown > crash_smp_send_stop > machine_kexec > BUG_ON(num_online_cpus() > 1); > > CPU 1: > panic() > local_irq_disable > panic_smp_self_stop > > If CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop(), kdump > fails. CPU1 can't receive the ipi irq, CPU1 will be always online. > I changed BUG_ON to WARN in kexec crash as arm64 does, kdump also fails. > Because num_online_cpus() > 1, can't disable the L2 in _soft_restart. > To fix this problem, this patch split out the panic_smp_self_stop() > and add set_cpu_online(smp_processor_id(), false). Thanks. I think this may as well go into arch/arm/kernel/smp.c - it won't be required for single-CPU systems, since there aren't "other" CPUs. It's probably also worth a comment above the function as to why we have this. > > Signed-off-by: Yufen Wang <wangyufen@huawei.com> > --- > arch/arm/kernel/setup.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c > index 31940bd..151861f 100644 > --- a/arch/arm/kernel/setup.c > +++ b/arch/arm/kernel/setup.c > @@ -602,6 +602,16 @@ static void __init smp_build_mpidr_hash(void) > } > #endif > > +void panic_smp_self_stop(void) > +{ > + printk(KERN_DEBUG "CPU %u will stop doing anything useful since another CPU has paniced\n", > + smp_processor_id()); > + set_cpu_online(smp_processor_id(), false); > + while (1) > + cpu_relax(); > + > +} > + > static void __init setup_processor(void) > { > struct proc_info_list *list; > -- > 2.7.4 > >
On 2018/11/1 19:34, Russell King - ARM Linux wrote: > On Thu, Nov 01, 2018 at 07:20:49PM +0800, Wang Yufen wrote: >> From: Yufen Wang <wangyufen@huawei.com> >> >> In case panic() and panic() called at the same time on different CPUS. >> For example: >> CPU 0: >> panic() >> __crash_kexec >> machine_crash_shutdown >> crash_smp_send_stop >> machine_kexec >> BUG_ON(num_online_cpus() > 1); >> >> CPU 1: >> panic() >> local_irq_disable >> panic_smp_self_stop >> >> If CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop(), kdump >> fails. CPU1 can't receive the ipi irq, CPU1 will be always online. >> I changed BUG_ON to WARN in kexec crash as arm64 does, kdump also fails. >> Because num_online_cpus() > 1, can't disable the L2 in _soft_restart. >> To fix this problem, this patch split out the panic_smp_self_stop() >> and add set_cpu_online(smp_processor_id(), false). > Thanks. > > I think this may as well go into arch/arm/kernel/smp.c - it won't be > required for single-CPU systems, since there aren't "other" CPUs. > > It's probably also worth a comment above the function as to why we > have this. Thanks. I will send v2. >> Signed-off-by: Yufen Wang <wangyufen@huawei.com> >> --- >> arch/arm/kernel/setup.c | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c >> index 31940bd..151861f 100644 >> --- a/arch/arm/kernel/setup.c >> +++ b/arch/arm/kernel/setup.c >> @@ -602,6 +602,16 @@ static void __init smp_build_mpidr_hash(void) >> } >> #endif >> >> +void panic_smp_self_stop(void) >> +{ >> + printk(KERN_DEBUG "CPU %u will stop doing anything useful since another CPU has paniced\n", >> + smp_processor_id()); >> + set_cpu_online(smp_processor_id(), false); >> + while (1) >> + cpu_relax(); >> + >> +} >> + >> static void __init setup_processor(void) >> { >> struct proc_info_list *list; >> -- >> 2.7.4 >> >>
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c index 31940bd..151861f 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -602,6 +602,16 @@ static void __init smp_build_mpidr_hash(void) } #endif +void panic_smp_self_stop(void) +{ + printk(KERN_DEBUG "CPU %u will stop doing anything useful since another CPU has paniced\n", + smp_processor_id()); + set_cpu_online(smp_processor_id(), false); + while (1) + cpu_relax(); + +} + static void __init setup_processor(void) { struct proc_info_list *list;