From: Borislav Petkov <bp@alien8.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>,
Tony Luck <tony.luck@intel.com>, x86-ml <x86@kernel.org>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] #MC mess
Date: Tue, 18 Feb 2020 20:50:35 +0100 [thread overview]
Message-ID: <20200218195035.GN14449@zn.tnic> (raw)
In-Reply-To: <20200218131158.693eeefc@gandalf.local.home>
On Tue, Feb 18, 2020 at 01:11:58PM -0500, Steven Rostedt wrote:
> What's the issue with tracing? Does this affect the tracing done by the
> edac_mc_handle_error code?
>
> It has a trace event in it, that the rasdaemon uses.
Nah, that code is called from process context.
The problem with tracing the #MC handler is the same as tracing the NMI
handler. And the NMI handler does all kinds of dancing wrt breakpoints
and nested NMIs and the #MC handler doesn't do any of that. Not sure if
it should at all, btw.
> I believe static_key_disable() sleeps, and does all kinds of crazing
> things (like update the code).
True story, thanks for that hint!
static_key_disable()
|-> cpus_read_lock()
|-> percpu_down_read(&cpu_hotplug_lock)
|->might_sleep()
Yuck. Which means, the #MC handler must switch to __rdmsr()/__wrmsr()
now.
I wish I could travel back in time and NAK the hell of that MSR
tracepoint crap.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2020-02-18 19:50 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 17:31 [RFC] #MC mess Borislav Petkov
2020-02-18 18:11 ` Steven Rostedt
2020-02-18 19:50 ` Borislav Petkov [this message]
2020-02-18 20:08 ` Steven Rostedt
2020-02-18 20:30 ` Peter Zijlstra
2020-02-18 20:52 ` Borislav Petkov
2020-02-18 18:20 ` Luck, Tony
2020-02-18 19:51 ` Borislav Petkov
2020-02-18 19:54 ` Luck, Tony
2020-02-18 20:00 ` Borislav Petkov
2020-02-18 20:05 ` Luck, Tony
2020-02-18 20:02 ` Peter Zijlstra
2020-02-18 20:09 ` Borislav Petkov
2020-02-18 20:11 ` Luck, Tony
2020-02-18 20:34 ` Peter Zijlstra
2020-02-18 21:49 ` Peter Zijlstra
2020-02-18 21:53 ` Peter Zijlstra
2020-02-18 22:41 ` Frederic Weisbecker
2020-02-18 22:40 ` Frederic Weisbecker
2020-02-18 23:17 ` Andy Lutomirski
2020-02-18 23:10 ` Andy Lutomirski
2020-02-18 23:17 ` Steven Rostedt
2020-02-19 0:15 ` Andy Lutomirski
2020-02-19 8:15 ` Peter Zijlstra
2020-02-19 14:21 ` Steven Rostedt
2020-02-19 14:43 ` Borislav Petkov
2020-02-19 15:05 ` Peter Zijlstra
2020-02-19 15:20 ` Andy Lutomirski
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