Re: [PATCH v2 2/2] MIPS: fix kernel lockup or crash after CPU offline/online

[James Hogan]

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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