From: James Hogan <james.hogan@imgtec.com>
To: "Maciej W. Rozycki" <macro@linux-mips.org>,
Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Ralf Baechle <ralf@linux-mips.org>,
David Daney <david.daney@cavium.com>, <linux-mips@linux-mips.org>,
<linux-kernel@vger.kernel.org>,
Hemmo Nieminen <hemmo.nieminen@iki.fi>, <stable@vger.kernel.org>
Subject: Re: [PATCH v2 2/2] MIPS: fix kernel lockup or crash after CPU offline/online
Date: Fri, 30 Jan 2015 10:22:17 +0000 [thread overview]
Message-ID: <54CB5B59.5050203@imgtec.com> (raw)
In-Reply-To: <alpine.LFD.2.11.1501300347170.28301@eddie.linux-mips.org>
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Hi Maciej,
On 30/01/15 09:25, Maciej W. Rozycki wrote:
> On Thu, 15 Jan 2015, Aaro Koskinen wrote:
>
>> As printk() invocation can cause e.g. a TLB miss, printk() cannot be
>> called before the exception handlers have been properly initialized.
>> This can happen e.g. when netconsole has been loaded as a kernel module
>> and the TLB table has been cleared when a CPU was offline.
>
> Hmm, why can a call to `printk' cause a TLB miss, what's so special about
> this function? Does it use kernel mapped addresses for any purpose such
> as `vmalloc'?
It would be the fact netconsole (or whatever other console is in use) is
built as a kernel module, memory for which is allocated from the vmalloc
area.
Cheers
James
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WARNING: multiple messages have this Message-ID (diff)
From: James Hogan <james.hogan@imgtec.com>
To: "Maciej W. Rozycki" <macro@linux-mips.org>,
Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Ralf Baechle <ralf@linux-mips.org>,
David Daney <david.daney@cavium.com>,
linux-mips@linux-mips.org, linux-kernel@vger.kernel.org,
Hemmo Nieminen <hemmo.nieminen@iki.fi>,
stable@vger.kernel.org
Subject: Re: [PATCH v2 2/2] MIPS: fix kernel lockup or crash after CPU offline/online
Date: Fri, 30 Jan 2015 10:22:17 +0000 [thread overview]
Message-ID: <54CB5B59.5050203@imgtec.com> (raw)
Message-ID: <20150130102217.novCAnuF7cVPNmnmnYqfqrXReryKy0c_0fAXU7B0fCE@z> (raw)
In-Reply-To: <alpine.LFD.2.11.1501300347170.28301@eddie.linux-mips.org>
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Hi Maciej,
On 30/01/15 09:25, Maciej W. Rozycki wrote:
> On Thu, 15 Jan 2015, Aaro Koskinen wrote:
>
>> As printk() invocation can cause e.g. a TLB miss, printk() cannot be
>> called before the exception handlers have been properly initialized.
>> This can happen e.g. when netconsole has been loaded as a kernel module
>> and the TLB table has been cleared when a CPU was offline.
>
> Hmm, why can a call to `printk' cause a TLB miss, what's so special about
> this function? Does it use kernel mapped addresses for any purpose such
> as `vmalloc'?
It would be the fact netconsole (or whatever other console is in use) is
built as a kernel module, memory for which is allocated from the vmalloc
area.
Cheers
James
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next prev parent reply other threads:[~2015-01-30 10:22 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-15 21:01 [PATCH v2 1/2] MIPS: OCTEON: fix kernel crash when offlining a CPU Aaro Koskinen
2015-01-15 21:01 ` [PATCH v2 2/2] MIPS: fix kernel lockup or crash after CPU offline/online Aaro Koskinen
2015-01-30 9:25 ` Maciej W. Rozycki
2015-01-30 10:22 ` James Hogan [this message]
2015-01-30 10:22 ` James Hogan
2015-01-30 12:47 ` Maciej W. Rozycki
2015-01-30 14:59 ` James Hogan
2015-01-30 14:59 ` James Hogan
2015-01-30 17:55 ` Aaro Koskinen
2015-01-30 18:23 ` James Hogan
2015-01-30 18:23 ` James Hogan
2015-01-30 18:53 ` Maciej W. Rozycki
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