Re: [Xen-devel] What is the current state of Dom0 kernel support? / crash

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Wed, Jul 22, 2009 at 01:25:45PM -0700, Jeremy Fitzhardinge wrote:
> On 07/22/09 12:57, Pasi Kärkkäinen wrote:
> > On Wed, Jul 22, 2009 at 10:35:30PM +0300, Pasi Kärkkäinen wrote:
> >   
> >> On Wed, Jul 22, 2009 at 12:14:37PM -0700, Jeremy Fitzhardinge wrote:
> >>     
> >>> On 07/21/09 06:03, Pasi Kärkkäinen wrote:
> >>>       
> >>>> I just tried the latest 32b PAE rebase/master tree (2.6.31-rc3).
> >>>>
> >>>> http://pasik.reaktio.net/xen/pv_ops-dom0-debug/pv_ops-dom0-log-10-rebase-master-with-highpte.txt
> >>>>
> >>>> Checking if this processor honours the WP bit even in supervisor mode...
> >>>> BUG: unable to handle kernel NULL pointer dereference at (null)
> >>>> IP: [<c058cdcb>] xen_evtchn_do_upcall+0xcc/0x13f
> >>>> *pdpt = 000000003d275001 
> >>>> Thread overran stack, or stack corrupted
> >>>> Oops: 0000 [#1] SMP 
> >>>> last sysfs file: 
> >>>> Modules linked in:
> >>>>
> >>>> Pid: 0, comm: swapper Not tainted (2.6.31-rc3 #20) P8SC8
> >>>> EIP: 0061:[<c058cdcb>] EFLAGS: 00010046 CPU: 0
> >>>> EIP is at xen_evtchn_do_upcall+0xcc/0x13f
> >>>> EAX: 00000000 EBX: ffffffff ECX: 00000000 EDX: 00000000
> >>>> ESI: 00000000 EDI: c08ec558 EBP: c087eedc ESP: c087eea0
> >>>>  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: e021
> >>>> Process swapper (pid: 0, ti=c087e000 task=c083b1a0 task.ti=c087e000)
> >>>> Stack:
> >>>>  00001a6e 00000220 00000200 00000000 00000000 00000000 e3201014 c08ec558
> >>>> <0> c087eee4 f5681000 e3201010 00000000 00000000 c09017f8 f54ff000 
> >>>> c087ef20
> >>>> <0> c0409927 00000000 c09017f8 f54ff000 c09017f8 f54ff000 c087ef20 
> >>>> c0843f70
> >>>> Call Trace:
> >>>>  [<c0409927>] ? xen_do_upcall+0x7/0xc
> >>>>  [<c0404581>] ? xen_pte_clear+0x9/0x12
> >>>>  [<c0427a94>] ? set_pte_vaddr+0xb4/0xc4
> >>>>  [<c0426c8c>] ? __native_set_fixmap+0x25/0x30
> >>>>  [<c040471a>] ? xen_set_fixmap+0xc7/0xcc
> >>>>  [<c0897d86>] ? mem_init+0x24a/0x298
> >>>>  [<c088367e>] ? start_kernel+0x14b/0x2cd
> >>>>  [<c088336f>] ? unknown_bootoption+0x0/0x18e
> >>>>  [<c0883082>] ? i386_start_kernel+0x71/0x79
> >>>>  [<c0886188>] ? xen_start_kernel+0x52a/0x533
> >>>> Code: d0 89 45 cc 89 55 c8 eb 16 0f bc c8 03 4d d4 8b 04 8a 83 f8 ff 74 
> >>>> f8
> >>>> 8b 55 e4 e8 36 de e7 ff 8b 55 f0 8b 45 d0 03 
> >>>> 05 1c 0c 97 c0 <8b> 0c 10 8b 55 e8 8b 45 cc 23 0c 82 8b 45 c8 8b 04 82 
> >>>> 8b 15
> >>>> 18 
> >>>> EIP: [<c058cdcb>] xen_evtchn_do_upcall+0xcc/0x13f SS:ESP e021:c087eea0
> >>>> CR2: 0000000000000000
> >>>> ---[ end trace 4eaa2a86a8e2da22 ]---
> >>>> Kernel panic - not syncing: Fatal exception in interrupt
> >>>>   
> >>>>         
> >>> Haven't seen that one before.  
> >>>
> >>>       
> >> Ok. I've seen many people report crashes during startup with rebase/master
> >> on 32b PAE. I assume they're seeing this same issue.
> >>
> >>     
> >>> The stack backtrace is a bit fuzzy; do you have CONFIG_FRAMEPOINTER 
> >>> enabled?  
> >>> And if you have CONFIG_DEBUGINFO enabled, you can map the eip c058cdcb 
> >>> to a specific source line (its not clear to me which pointer is NULL).
> >>>
> >>>       
> >> [root@dom0test linux-2.6-xen]# grep -i CONFIG_FRAMEPOINTER .config
> >> [root@dom0test linux-2.6-xen]# grep -i CONFIG_DEBUGINFO .config
> >> [root@dom0test linux-2.6-xen]# 
> >>
> >> Unfortunately those were not enabled.. I'll build a new kernel with
> >> CONFIG_DEBUGINFO enabled.
> >>
> >>     
> >
> > Actually CONFIG_DEBUG_INFO was enabled, if you meant that? 
> >   
> 
> Yes, that's it.
> > (gdb) x/i 0xc058cdcb
> >   
> 
> Try "list *0xc058cdcb".
> 

(gdb) list *0xc058cdcb
0xc058cdcb is in active_evtchns (drivers/xen/events.c:237).
232
233     static inline unsigned long active_evtchns(unsigned int cpu,
234                                                struct shared_info *sh,
235                                                unsigned int idx)
236     {
237             return (sh->evtchn_pending[idx] &
238                     cpu_evtchn_mask(cpu)[idx] &
239                     ~sh->evtchn_mask[idx]);
240     }
241
(gdb)


-- Pasi

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