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Re: BUG: unable to handle kernel paging request at xxx

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To: Thomas Meyer <thomas@...>
Cc: <linux-kernel@...>, <arges@...>
Date: Tuesday, May 6, 2008 - 2:33 pm

Hi Thomas,

Thanks for the feedback.  Would you also send your .config file as well
as a summary of the system configuration (cpu type, etc.)?

From the log it looks like it may be related to another oprofile error
that Chris is working on.  I've included him on the Cc list and duplicated
his email message below.

Thanks,
Mike

Thomas Meyer wrote:



Subject: Hotplug CPU support for Oprofile
From: Chris J Arges <arges@linux.vnet.ibm.com>
Reply-To: arges@linux.vnet.ibm.com
To: travis@sgi.com, phil.el@wanadoo.fr
Cc: mpjohn@us.ibm.com
Content-Type: text/plain; charset=UTF-8
Organization: IBM
Date: Mon, 05 May 2008 13:34:03 -0500
Message-Id: <1210012443.6374.23.camel@snuffleupagus>


Mike,
I was wondering what your rationale behind using per_cpu variables for
the cpu buffers in oprofile versus using percpu_alloc, percpu_free?
For instance:

        DEFINE_PER_CPU_SHARED_ALIGNED(struct oprofile_cpu_buffer,
        cpu_buffer);

        void free_cpu_buffers(void)
        {
                int i;
        
                for_each_online_cpu(i)
                        vfree(per_cpu(cpu_buffer, i).buffer);
        
        }

Could it be possible to write it like this:
        
        struct oprofile_cpu_buffer *cpu_buffer;
        
        void free_cpu_buffers(void)
        {
        	percpu_free(cpu_buffer);
        }
        

Phillipe, Mike,
I am currently working on a patch for enabling hotplug cpu support for
oprofile as currently oprofile crashes whenever cpus are onlined of
offlined. So far my patch registers a callback function for hotplug
events, and checked if a cpu has been onlined/offlined and then
allocs/frees a cpu buffer accordingly. 

I am wondering if you have any further recommendations as to approaching
adding hotplug support. I am still fairly new to oprofile/linux kernel
but I would like to contribute, please forgive any newbie mistakes.
Thanks!

-- 
Chris J Arges
Software Engineer
IBM Linux Technology Center
Austin, TX
arges@linux.vnet.ibm.com
--
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Messages in current thread:
BUG: unable to handle kernel paging request at xxx, Thomas Meyer, (Tue May 6, 2:15 pm)
Re: BUG: unable to handle kernel paging request at xxx, Mike Travis, (Tue May 6, 2:33 pm)
Re: BUG: unable to handle kernel paging request at xxx, Thomas Meyer, (Tue May 6, 3:26 pm)
Re: BUG: unable to handle kernel paging request at xxx, Thomas Meyer, (Thu May 8, 5:32 pm)
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