linux-kernel - Re: [PATCH v7 2/2] x86/apic: x2apic write eoi msr notrace

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Date:   Mon, 7 Nov 2016 10:52:43 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kvm <kvm@...r.kernel.org>, Ingo Molnar <mingo@...nel.org>,
        Mike Galbraith <efault@....de>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [PATCH v7 2/2] x86/apic: x2apic write eoi msr notrace

2016-11-03 5:10 GMT+08:00 Borislav Petkov <bp@...en8.de>:
> On Mon, Oct 31, 2016 at 09:37:02AM +0800, Wanpeng Li wrote:
>> From: Wanpeng Li <wanpeng.li@...mail.com>
>>
>> | RCU used illegally from idle CPU!
>> | rcu_scheduler_active = 1, debug_locks = 0
>> | RCU used illegally from extended quiescent state!
>> | no locks held by swapper/1/0.
>> |
>> |  [<ffffffff9d492b95>] do_trace_write_msr+0x135/0x140
>> |  [<ffffffff9d06f860>] native_write_msr+0x20/0x30
>> |  [<ffffffff9d065fad>] native_apic_msr_eoi_write+0x1d/0x30
>> |  [<ffffffff9d05bd1d>] smp_reschedule_interrupt+0x1d/0x30
>> |  [<ffffffff9d8daec6>] reschedule_interrupt+0x96/0xa0
>
> Please remove the text between [] and the offsets after "+..." - those
> are useless in a commit message.
>
>> Reschedule interrupt may be called in cpu idle state. This causes lockdep
>
> s/cpu/CPU/
>
>> check warning above.
>>
>> As Peterz pointed out:
>>
>> | So now we're making a very frequent interrupt slower because of debug
>> | code.
>> |
>> | The thing is, many many smp_reschedule_interrupt() invocations don't
>> | actually execute anything much at all and are only send to tickle the
>
> s/send/sent/

I will send a new version to clean it up.

Regards,
Wanpeng Li