linux-kernel - Re: [PATCH v11 3/4] x86, mce: Add __mcsafe

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Message-ID: <20160218201440.GA25570@gmail.com>
Date:	Thu, 18 Feb 2016 21:14:40 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	"Luck, Tony" <tony.luck@...el.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH v11 3/4] x86, mce: Add __mcsafe_copy()


* Luck, Tony <tony.luck@...el.com> wrote:

> On Thu, Feb 18, 2016 at 10:12:42AM -0800, Linus Torvalds wrote:
> > On Wed, Feb 17, 2016 at 10:20 AM, Tony Luck <tony.luck@...el.com> wrote:
> > >
> > > If we faulted during the copy, then 'trapnr' will say which type
> > > of trap (X86_TRAP_PF or X86_TRAP_MC) and 'remain' says how many
> > > bytes were not copied.
> > 
> > So apart from the naming, a couple of questions:
> > 
> >  - I'd like to see the actual *use* case explained, not just what it does.
> 
> First user is libnvdimm. Dan Williams already has code to use this so that 
> kernel code accessing persistent memory can return -EIO to a user instead of 
> crashing the system if the cpu runs into an uncorrected error during the copy.

Are these the memcpy_*_pmem() calls in drivers/nvdimm/pmem.c? Is there any actual 
patch to look at?

Thanks,

	Ingo