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

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Message-ID: <20141112172739.GH16807@pd.tnic>
Date:	Wed, 12 Nov 2014 18:27:39 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	"Chen, Gong" <gong.chen@...ux.intel.com>, tony.luck@...el.com,
	x86@...nel.org, Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...capital.net>
Subject: Re: [PATCH v2 4/5] x86/mce: Simplify flow when handling recoverable
 memory errors

On Wed, Nov 12, 2014 at 06:20:58PM +0100, Oleg Nesterov wrote:
> Sorry, I am a bit confused...
> 
> On 11/11, Borislav Petkov wrote:
> >
> > Roughly speaking, we want to be able to mark a task with the sign of
> > death and to kill it, if needed.
> 
> "it" is current, yes?

Yes.

> So I agree with Andy, task_work_add() can work and you can also pass
> paddr/restartable to the handler.

Yes, and it is much simpler than changing the entry.S glue to switch to
the kernel stack for our purposes.

> But,
> 
> > The important part is *before* it
> > gets to run again.
> 
> But it is already running? Perhaps you meant "before it returns to
> user-mode" ?

Right, it runs, while it does so, it triggers an MCE because it touches
some corrupted memory, we jump to the #MC handler and before we return
to user space, we kill that process.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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