Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage!

From	Borislav Petkov <bp@alien8.de>
Newsgroups	linux.kernel
Subject	Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage!
Date	2016-11-30 10:10 +0100
Message-ID	<sJ93Q-49f-11@gated-at.bofh.it> (permalink)
References	(5 earlier) <sFZkq-3oh-15@gated-at.bofh.it> <sIQDT-yf-1@gated-at.bofh.it> <sIRgC-12s-23@gated-at.bofh.it> <sJ8Kt-3Ns-9@gated-at.bofh.it> <sJ8U9-3QS-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, Nov 30, 2016 at 09:54:58AM +0100, Thomas Gleixner wrote:
> Right, that's the safe bet. But I'm quite sure that the C1E crap only
> starts to work _after_ ACPI initialization.

Yap, I think it is an ACPI decision whether to enter C1E or not. And all
those boxes which are unaffected - they actually are but since the FW
doesn't enter C1E, they don't hit the bug.

> tick_force_broadcast() is irreversible

So if I let the cores in that small window use amd_e400_idle() and
then when I detect the machine doesn't enter C1E after all, I do
tick_broadcast_exit() on all cores in amd_e400_c1e_mask, then clear it
and free it, that would work?

Or do you see a better solution?

Thanks.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

Thread

Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage! Borislav Petkov <bp@alien8.de> - 2016-11-29 14:30 +0100
  Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage! Jiri Olsa <jolsa@redhat.com> - 2016-11-29 15:10 +0100
  Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage! Thomas Gleixner <tglx@linutronix.de> - 2016-11-29 15:10 +0100
    Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage! Borislav Petkov <bp@alien8.de> - 2016-11-30 09:50 +0100
      Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage! Thomas Gleixner <tglx@linutronix.de> - 2016-11-30 10:00 +0100
        Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage! Borislav Petkov <bp@alien8.de> - 2016-11-30 10:10 +0100
          Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage! Thomas Gleixner <tglx@linutronix.de> - 2016-11-30 10:20 +0100

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