linux-kernel - Re: [v5 5/6] powerpc/mce: Handle UE event for memcpy

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Message-Id: <1562838616.xzrha67fy6.astroid@bobo.none>
Date:   Thu, 11 Jul 2019 19:52:59 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     linux-kernel@...r.kernel.org,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Santosh Sivaraj <santosh@...six.org>
Cc:     "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Reza Arbab <arbab@...ux.ibm.com>,
        Balbir Singh <bsingharora@...il.com>,
        Chandan Rajendra <chandan@...ux.vnet.ibm.com>,
        christophe leroy <christophe.leroy@....fr>,
        Mahesh Salgaonkar <mahesh@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [v5 5/6] powerpc/mce: Handle UE event for memcpy_mcsafe

Santosh Sivaraj's on July 9, 2019 10:15 pm:
> If we take a UE on one of the instructions with a fixup entry, set nip
> to continue execution at the fixup entry. Stop processing the event
> further or print it.

So... what happens if we take a machine check while we happen to be
executing some other kernel operation with a fixup entry?

Or the other way around, what happens if memcpy_mcsafe takes a page
fault for some reason (e.g., kernel bug it tries to access unmapped
memory).

Thanks,
Nick