linux-kernel - Re: [PATCH 1/7] x86/mce: Provide a lockless memory pool to save error records

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Date:	Tue, 21 Jul 2015 12:08:24 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Borislav Petkov <bp@...e.de>
Cc:	Tony Luck <tony.luck@...el.com>, X86-ML <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>, ashok.raj@...el.com,
	gong.chen@...ux.intel.com, Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1/7] x86/mce: Provide a lockless memory pool to save
 error records


* Borislav Petkov <bp@...e.de> wrote:

> > So how are we going to report uncorrectable errors that forcibly crash/panic 
> > the system if we cannot use printk? How will the admin learn what was amiss?
> 
> There's no change to that policy - we still panic for MCEs of MCE_PANIC_SEVERITY 
> and higher. And mce_panic() does use printk() to dump that critical information.

Ok, I see: through mce_print().

> The gen_pool stuff is for MCEs for which the hw still raises an #MC exception 
> but the severity code determines that we don't need to panic but do recovery 
> action.
> 
> However, we don't want to call printk() from the #MC exception handler since it 
> is NMI-like atomic context and printk is not NMI-safe (yet). Those printks are 
> issued later, in process context when we're done with the exception handler and 
> recovery action.

Ok - no objections then.

Thanks,

	Ingo
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