From: Prarit Bhargava <prarit@redhat.com>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-kernel@vger.kernel.org, Tony Luck <tony.luck@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-edac@vger.kernel.org
Subject: Re: [PATCH] x86/mce: Fix initialization error warning
Date: Mon, 16 Jan 2017 18:13:39 -0500 [thread overview]
Message-ID: <587D53A3.1010305@redhat.com> (raw)
In-Reply-To: <20170116224316.bhnr4goijsh6h76o@pd.tnic>
On 01/16/2017 05:43 PM, Borislav Petkov wrote:
> On Mon, Jan 16, 2017 at 05:06:02PM -0500, Prarit Bhargava wrote:
>> Yes, it was loud enough to generate a bug report from a user.
>
> Yeah, because all users are sane and we should do whatever they want -
> no questions asked. Especially those who boot with "mce=off".
>
> Did you actually ask that user why she/he is even booting with
> "mce=off"?
Yes, mce=off is the default for kdump:
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory
mce=off numa=off udev.children-max=2 panic=10 rootflags=nofail
acpi_no_memhotplug transparent_hugepage=never"
There is a race condition between NMI completing on a CPU and the MCE
synchronization timing out that results in a kernel panic on the kdump kernel,
and a loss of the dump image. There have been a few attempts to fix it over the
years. It seems as simple as setting a flag in native_machine_crash_shutdown()
and querying it in do_machine_check() to avoid mce & nmi race.
P.
>
next prev parent reply other threads:[~2017-01-16 23:16 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-16 21:49 [PATCH] x86/mce: Fix initialization error warning Prarit Bhargava
2017-01-16 21:56 ` Thomas Gleixner
2017-01-16 21:56 ` Borislav Petkov
2017-01-16 22:06 ` Prarit Bhargava
2017-01-16 22:43 ` Borislav Petkov
2017-01-16 23:13 ` Prarit Bhargava [this message]
2017-01-16 23:32 ` Borislav Petkov
2017-01-16 23:50 ` Prarit Bhargava
2017-01-17 8:34 ` Thomas Gleixner
2017-01-17 9:08 ` Borislav Petkov
2017-01-17 9:09 ` Thomas Gleixner
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