Re: [PATCH] x86/MCE/AMD: fix warning about sleep-in-atomic at early boot

[Konstantin Khlebnikov]

On 31/10/2019 17.29, Borislav Petkov wrote:
> On Thu, Oct 31, 2019 at 04:04:48PM +0300, Konstantin Khlebnikov wrote:
> > Function smca_configure() is called only for current cpu thus
> > rdmsr_safe_on_cpu() could be replaced with atomic rdmsr_safe().
> >
> >   BUG: sleeping function called from invalid context at kernel/sched/completion.c:99
> >   in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1
> >   CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.79-16 #1
> 					     ^^^^^^^^^^
>
> I'm assuming you hit this on latest upstream too?

I tried 5.4 once but there was no warning.
Code in 4.19 and in mainline almost the same.

Probably hardware needs full power cycle to reset state or something else.

> >   Hardware name: GIGABYTE R181-Z90-00/MZ91-FS0-00, BIOS R11 10/25/2019
> >   Call Trace:
> >    dump_stack+0x5c/0x7b
> >    ___might_sleep+0xec/0x110
> >    wait_for_completion+0x39/0x160
> >    ? __rdmsr_safe_on_cpu+0x45/0x60
> >    rdmsr_safe_on_cpu+0xae/0xf0
> >    ? wrmsr_on_cpus+0x20/0x20
> >    ? machine_check_poll+0xfd/0x1f0
> >    ? mce_amd_feature_init+0x190/0x2d0
> >    mce_amd_feature_init+0x190/0x2d0
> >    mcheck_cpu_init+0x11a/0x460
> >    identify_cpu+0x3e2/0x560
> >    identify_secondary_cpu+0x13/0x80
> >    smp_store_cpu_info+0x45/0x50
> >    start_secondary+0xaa/0x200
> >    secondary_startup_64+0xa4/0xb0
> >
> > Except warning in kernel log everything works fine.
> >
> > Fixes: 5896820e0aa3 ("x86/mce/AMD, EDAC/mce_amd: Define and use tables for known SMCA IP types")
> > Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
> > ---
> >   arch/x86/kernel/cpu/mce/amd.c |    2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
> > index 6ea7fdc82f3c..c7ab0d38af79 100644
> > --- a/arch/x86/kernel/cpu/mce/amd.c
> > +++ b/arch/x86/kernel/cpu/mce/amd.c
> > @@ -269,7 +269,7 @@ static void smca_configure(unsigned int bank, unsigned int cpu)
> >   	if (smca_banks[bank].hwid)
> >   		return;
> >   
> > -	if (rdmsr_safe_on_cpu(cpu, MSR_AMD64_SMCA_MCx_IPID(bank), &low, &high)) {
> > +	if (rdmsr_safe(MSR_AMD64_SMCA_MCx_IPID(bank), &low, &high)) {
>
> Yazen, any objections?