linux-kernel - Re: [PATCH v10 1/7] powerpc/mce: Schedule work from irq

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Date:   Tue, 20 Aug 2019 00:08:46 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     Linux Kernel <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.ibm.com>,
        christophe leroy <christophe.leroy@....fr>,
        Mahesh Salgaonkar <mahesh@...ux.ibm.com>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>, stable@...r.kernel.org
Subject: Re: [PATCH v10 1/7] powerpc/mce: Schedule work from irq_work

Santosh Sivaraj's on August 15, 2019 10:39 am:
> schedule_work() cannot be called from MCE exception context as MCE can
> interrupt even in interrupt disabled context.

The powernv code doesn't do this in general, rather defers kernel
MCEs. My patch series converts the pseries machine check exception
code over to the same.

However there remain special cases where that's not true for
powernv, e.g., the machine check stack overflow or unrecoverable
MCE paths try to force it through so something gets printed. We
probably shouldn't even try to do memory failure in these cases.

Still, shouldn't hurt to make this change and fixes the existing
"different" pseries code.

Thanks,
Nick

> fixes: 733e4a4c ("powerpc/mce: hookup memory_failure for UE errors")
> Suggested-by: Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>
> Signed-off-by: Santosh Sivaraj <santosh@...six.org>
> Reviewed-by: Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>
> Acked-by: Balbir Singh <bsingharora@...il.com>
> Cc: stable@...r.kernel.org # v4.15+

Reviewed-by: Nicholas Piggin <npiggin@...il.com>