linux-kernel - Re: Crash during vmcore

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Date:	Thu, 17 Nov 2011 08:40:33 -0800
From:	Tim Hartrick <tim@...ecast.com>
To:	Dave Young <dyoung@...hat.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


Dave, Tejun, Americo,

Attached find three configs:

Ubuntu 2.6.32-21-server - works
Ubuntu 2.6.38-8-server - fails
Ubuntu 3.3.1-030101-generic (stable) - fails

On Thu, 2011-11-17 at 15:21 +0800, Dave Young wrote:
> 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
> > 
> 
> 
> 


View attachment "config-2.6.32-21-server" of type "text/x-mpsub" (110473 bytes)

View attachment "config-2.6.38-8-server" of type "text/x-mpsub" (130421 bytes)

View attachment "config-3.1.1-030101-generic" of type "text/x-mpsub" (136285 bytes)