linux-kernel - Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic'

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Message-ID: <CAPcyv4j1=Cs84nn6n-9vygSJ2Ei9Z3Gw7hCzyBzo+GyLKWaTUg@mail.gmail.com>
Date:   Wed, 12 Apr 2017 13:55:22 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     "Verma, Vishal L" <vishal.l.verma@...el.com>,
        "bp@...e.de" <bp@...e.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
        "ross.zwisler@...ux.intel.com" <ross.zwisler@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>
Subject: Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic'

On Wed, Apr 12, 2017 at 1:52 PM, Luck, Tony <tony.luck@...el.com> wrote:
> On Wed, Apr 12, 2017 at 01:27:05PM -0700, Verma, Vishal L wrote:
>> >     /* We only care about memory errors */
>> >     if (!(mce->status & MCACOD))
>> >             return NOTIFY_DONE;
>
> N.B. that isn't a valid test that this is a memory error. You need
>
>
>         if (!(m->status & 0xef80) == BIT(7))
>                 return NOTIFY_DONE;
>
> See: Intel SDM Volume 3B - 15.9.2 Compound Error Codes

But Vishal's point is that even if we get this check correct the
notifier still requires no sleeping operations. So we would need to
move recoverable notifications to a separate blocking notifier chain.