linux-kernel - Re: Crash during vmcore

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Date:	Thu, 17 Nov 2011 15:21:48 +0800
From:	Dave Young <dyoung@...hat.com>
To:	Tim Hartrick <tim@...ecast.com>
CC:	WANG Cong <xiyou.wangcong@...il.com>, Tejun Heo <tj@...nel.org>,
	kexec@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: Crash during vmcore_init

On 11/17/2011 01:22 PM, Tim Hartrick wrote:

> Tejun, Dave,
> 
> I will be happy to answer any questions about our environment or test
> debug or other patches.  Just tell me what you need.


Thank you. Can you share your kernel config?

> 
> tim
> 
> On Nov 16, 2011 8:44 PM, "Dave Young" <dyoung@...hat.com
> <mailto:dyoung@...hat.com>> wrote:
> 
>     On 11/17/2011 12:34 PM, Tejun Heo wrote:
> 
>     > Hello,
>     >
>     > On Wed, Nov 16, 2011 at 7:30 PM, Dave Young <dyoung@...hat.com
>     <mailto:dyoung@...hat.com>> wrote:
>     >> This addr is converted to an invalid phys address,
>     >
>     > I'm a bit lost on the context here. Who's calling
>     per_cpu_ptr_to_phys()?
> 
> 
>     It's drivers/base/cpu.c : show_crash_notes()
> 
>     >
>     >> looking the code below:
>     >>       if (in_first_chunk) {
>     >>                if (!is_vmalloc_addr(addr))
>     >>                        return __pa(addr);
>     >>                else
>     >>                        return page_to_phys(vmalloc_to_page(addr));
>     >>        } else
>     >>                return page_to_phys(pcpu_addr_to_page(addr));
>     >>
>     >> I dont understand per cpu allocation well, if addr is not in
>     first chunk
>     >> then it should be in vmalloc area?
>     >
>     > Yes, it is. First chunk can be embedded in the kernel linear address
>     > space but from the second one, it's always set up from the top of the
>     > vmalloc area with the same offset layout as the first chunk.
> 
> 
>     in this case ffff880667c19ad0 fall out of vmalloc area and it's not in
>     first chunk also.
> 
>     >
>     >> Tejun, do you have any idea about this?
>     >
>     > Can you please tell me how to reproduce the problem? I'll try to find
>     > out what's going on.
> 
> 
>     make sure kernel support CRASH DUMP, then cat
>     /sys/devices/system/cpu/cpu[x]/crash_notes
> 
>     Tim Hartrick <tim@...ecast.com <mailto:tim@...ecast.com>> reported
>     the problem when test kdump.
>     But I can not reproduce this. I think tim can help to test
> 
>     >
>     > Thanks.
>     >
> 
> 
> 
>     --
>     Thanks
>     Dave
> 



-- 
Thanks
Dave
--
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