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

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Date:   Fri, 1 Nov 2019 16:39:17 +0300
From:   Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:     Borislav Petkov <bp@...en8.de>,
        Yazen Ghannam <Yazen.Ghannam@....com>
Cc:     Tony Luck <tony.luck@...el.com>, linux-kernel@...r.kernel.org,
        linux-edac@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH] x86/MCE/AMD: fix warning about sleep-in-atomic at early
 boot

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@...dex-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?
>