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

["Ghannam, Yazen" <Yazen.Ghannam@amd.com>]

> -----Original Message-----
> From: Borislav Petkov <bp@alien8.de>
> Sent: Thursday, October 31, 2019 10:30 AM
> To: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>; Ghannam, Yazen <Yazen.Ghannam@amd.com>
> Cc: Tony Luck <tony.luck@intel.com>; linux-kernel@vger.kernel.org; linux-edac@vger.kernel.org; x86@kernel.org
> Subject: Re: [PATCH] x86/MCE/AMD: fix warning about sleep-in-atomic at early boot
> 
> 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?
> 
> >  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@yandex-team.ru>
> > ---
> >  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?
> 

This looks good to me.

We can go further and remove the "cpu" parameter from this entire function.
But that can be another patch.

Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com>

Thanks,
Yazen