linux-kernel - Re: [PATCH v2 4/5] x86/mce: Simplify flow when handling recoverable memory errors

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Date:	Tue, 11 Nov 2014 10:34:46 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Chen Gong <gong.chen@...ux.intel.com>, X86 ML <x86@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Tony Luck <tony.luck@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 4/5] x86/mce: Simplify flow when handling recoverable
 memory errors

On Tue, Nov 11, 2014 at 10:22 AM, Borislav Petkov <bp@...en8.de> wrote:
> On Tue, Nov 11, 2014 at 09:15:18AM -0800, Andy Lutomirski wrote:
>> Oh -- does it need to sleep?
>
> Oh yeah, iterates over all tasks and generally async access to VM stuff.
> You can have a look if bored: mm/memory-failure.c
>
> :-)
>
>> I find myself wondering whether a much cleaner solution might be to
>> sync regs and switch stacks before invoking do_machine_check rather
>> than afterwards.  Then do_machine_check would really be completely
>> non-atomic.  It would add a few lines of asm, though.
>
> That's like wagging the dog.

Wagging this particular dog might shake some loose fur off.  If we did
this for all paranoid entries, then paranoid_userspace could just be
deleted.  :)

>
> I'd prefer much more to actually have a mechanism to do something to
> tasks before scheduling them in.

Like task_work_add?

--Andy
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