Re: [Xen-devel] Kernel panic, reboot in 5 seconds

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Thu, May 14, 2015 at 2:00 PM, Mr Idris <mr@xxxxxxxxxxxx> wrote:
> I'm trying to create cpu scheduler on xen 4.4.1 using debian 7 which
> inspired by arinc653 scheduler. When i use it, it gives me something
> like kernel panic and reboot in 5 secs before go in to the system. I
> don't know how to procced  to fix the errors, Here is some debug
> errors :
>
> (XEN) Debugging connection not set up.
> (XEN) ----[ Xen-4.4.1  x86_64  debug=y  Not tainted ]----
> (XEN) CPU:    0
> (XEN) RIP:    e008:[<ffff82d080126dbe>] schedule+0x408/0x5df
> (XEN) RFLAGS: 0000000000010006   CONTEXT: hypervisor
> (XEN) rax: 000000003c02a15f   rbx: ffff8300dfb98000   rcx: 0000000000000001
> (XEN) rdx: 0000000000000000   rsi: 0000000000000005   rdi: ffff82d0803196ec
> (XEN) rbp: ffff82d0802d7eb0   rsp: ffff82d0802d7e30   r8:  ffff82d080319700
> (XEN) r9:  ffff82d080315600   r10: 0000000202746bd9   r11: 0000000000000003
> (XEN) r12: 000000003c02a15f   r13: 0000000000000000   r14: ffff82d0803196e8
> (XEN) r15: 0000000000000001   cr0: 000000008005003b   cr4: 00000000000426f0
> (XEN) cr3: 00000000df889000   cr2: 00000000000000c8
> (XEN) ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: 0000   cs: e008
> (XEN) Xen stack trace from rsp=ffff82d0802d7e30:
> (XEN)    ffff82d0802d7e60 ffff82d080319700 00000000002d7e60 ffff82d0803196e0
> (XEN)    ffff82d08012a344 ffff82d080319880 ffff82d0802d7eb0 0000000000000000
> (XEN)    000000003c02a17d 0000000000040000 0000000000000001 ffff82d0802eff00
> (XEN)    ffff82d0802eff00 ffff82d0802d0000 ffffffffffffffff ffff83000008efb0
> (XEN)    ffff82d0802d7ee0 ffff82d080129cb9 ffff82d0802d0000 ffff82d0802d0000
> (XEN)    0000000000000001 ffff82d08027ab60 ffff82d0802d7ef0 ffff82d080129d12
> (XEN)    ffff82d0802d7f10 ffff82d080160355 00000000df890000 0000000000040000
> (XEN)    ffff82d0802d7ef0 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 ffff8300dfb98000
> (XEN)    0000000000000000 0000000000000000
> (XEN) Xen call trace:
> (XEN)    [<ffff82d080126dbe>] schedule+0x408/0x5df
> (XEN)    [<ffff82d080129cb9>] __do_softirq+0x81/0x8c
> (XEN)    [<ffff82d080129d12>] do_softirq+0x13/0x15
> (XEN)    [<ffff82d080160355>] idle_loop+0x64/0x74
> (XEN)
> (XEN) Pagetable walk from 00000000000000c8:
> (XEN)  L4[0x000] = 0000000215507063 ffffffffffffffff
> (XEN)  L3[0x000] = 0000000215506063 ffffffffffffffff
> (XEN)  L2[0x000] = 0000000215505063 ffffffffffffffff
> (XEN)  L1[0x000] = 0000000000000000 ffffffffffffffff
> (XEN)
> (XEN) ****************************************
> (XEN) Panic on CPU 0:
> (XEN) FATAL PAGE FAULT
> (XEN) [error_code=0000]
> (XEN) Faulting linear address: 00000000000000c8
> (XEN) ****************************************
> (XEN)
> (XEN) Reboot in five seconds...
> (XEN) Debugging connection not set up.

Fundamentally, the bug you're getting is that you're dereferencing a
null pointer, probably into a struct (that's the "Faulting linear
address" -- 0xc8 will be the offset into the struct).

A full serial log from boot would be more helpful to figure out where
that dereference might be happening.

> One more thing, how to setup debugging connection here?
> Any suggestion is appreciated. Thank you very much.

I don't use the debugger personally; I tend to use printk.  It's also
useful to comb through the changes you've made to the code to make
sure you've set all the pointers which need to be set.

 -George

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel