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Subject: Re: use memcpy_mcsafe() for copy_to_iter() (was: Re: [PATCH v3 0/9] Series short description)
From:   Andy Lutomirski <luto@amacapital.net>
In-Reply-To: <CAPcyv4j2HQH1wdsGGWUAiXEKXeoMUWN_HeUEMmkv8PG7RUTtfw@mail.gmail.com>
Date:   Mon, 14 May 2018 10:53:51 -0700
Cc:     Ingo Molnar <mingo@kernel.org>,
        linux-nvdimm <linux-nvdimm@lists.01.org>,
        "Luck, Tony" <tony.luck@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mike Snitzer <snitzer@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>, X86 ML <x86@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        =?utf-8?Q?Mika_Penttil=C3=A4?= <mika.penttila@nextfour.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Christoph Hellwig <hch@lst.de>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>
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To:     Dan Williams <dan.j.williams@intel.com>
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> On May 14, 2018, at 8:52 AM, Dan Williams <dan.j.williams@intel.com> wrote=
:
>=20

>=20
> I think "happy" is a strong word when it comes to x86 machine check
> handling. My interpretation is that he and Andy acquiesced that this
> is about the best we can do with dax+mce as things stand today.


Agreed. I think it=E2=80=99s plausible that we could do slightly better for M=
CEs related to bad memory accessed through the direct map, but the code woul=
d be complicated and miserable to test, and it=E2=80=99s not even clear that=
 it would materially decrease the chance that we survive as compared to thes=
e patches.=