[ktap] Re: "BUG: unable to handle kernel paging request" after ktap script to trace SyS_write
- From: Azat Khuzhin <a3at.mail@xxxxxxxxx>
- To: ktap@xxxxxxxxxxxxx
- Date: Sun, 20 Oct 2013 20:01:53 +0400
On Sun, Oct 20, 2013 at 7:27 PM, Jovi Zhangwei <jovi.zhangwei@xxxxxxxxx> wrote:
> On Sun, Oct 20, 2013 at 10:22 PM, Azat Khuzhin <a3at.mail@xxxxxxxxx> wrote:
>> On Sun, Oct 20, 2013 at 12:50 PM, Jovi Zhangwei <jovi.zhangwei@xxxxxxxxx>
>> wrote:
>>> On Sat, Oct 19, 2013 at 5:06 PM, Azat Khuzhin <a3at.mail@xxxxxxxxx> wrote:
>>>> Hi all,
>>>>
>>>> I used next script, and after a few seconds of working, I have all ssh
>>>> sessions killed.
>>>> #! /usr/bin/env ktap
>>>> trace probe:SyS_write {
>>>> print(backtrace(0, 100))
>>>> }
>>>>
>>>> However, I can login after this, and have next messages in dmesg:
>>>>
>>> Hi Azat,
>>
>> Hi Jovi,
>>
>>>
>>> Thanks for your reporting, could you help to check if below two
>>> scripts works correctly?
>>>
>>> #! /usr/bin/env ktap
>>> trace probe:SyS_write {
>>> print_backtrace(0, 100)
>>> }
>>
>> [ 107.416689] BUG: unable to handle kernel paging request at
>> ffffffff621ee2b5
>> [ 107.417774] IP: [<ffffffff621ee2b5>] 0xffffffff621ee2b4
>> [ 107.418569] PGD 160c067 PUD 0
>> [ 107.419409] Oops: 0010 [#3] PREEMPT SMP
>> [ 107.420038] Modules linked in: ktapvm(O) nfsd auth_rpcgss
>> oid_registry nfs_acl nfs lockd fscache sunrpc loop fuse joydev
>> hid_generic usbhid hid snd_pcm microcode snd_page_alloc snd_timer snd
>> soundcore ohci_pci ohci_hcd ehci_hcd psmouse usbcore i2c_piix4
>> processor ac ther
>> mal_sys serio_raw pcspkr parport_pc usb_common evdev parport button
>> i2c_core ext4 crc16 jbd2 mbcache sd_mod sg crc_t10dif sr_mod cdrom
>> crct10dif_common ata_generic ahci libahci ata_piix libata e1000
>> scsi_mod
>> [ 107.420038] CPU: 1 PID: 2654 Comm: less Tainted: G D O
>> 3.12.0-rc5+ #40
>> [ 107.420038] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS
>> VirtualBox 12/01/2006
>> [ 107.420038] task: ffff88007a911790 ti: ffff88007a05c000 task.ti:
>> ffff88007a05c000
>> [ 107.420038] RIP: 0010:[<ffffffff621ee2b5>] [<ffffffff621ee2b5>]
>> 0xffffffff621ee2b4
>> [ 107.420038] RSP: 0018:ffff88007a05df78 EFLAGS: 00010293
>> [ 107.420038] RAX: 0000000000000001 RBX: 00000000000003ff RCX:
>> 0000000000000001
>> [ 107.420038] RDX: 00000000000003ff RSI: 0000000000628940 RDI:
>> 0000000000000001
>> [ 107.420038] RBP: 000000000000005f R08: 0000000001e49c20 R09:
>> 0000000000000000
>> [ 107.420038] R10: 0000000000000001 R11: 0000000000000246 R12:
>> 0000000000000000
>> [ 107.420038] R13: 0000000000000043 R14: 0000000000000000 R15:
>> 0000000000000000
>> [ 107.420038] FS: 00007ff4a1bda700(0000) GS:ffff88007fd00000(0000)
>> knlGS:0000000000000000
>> [ 107.420038] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
>> [ 107.420038] CR2: ffffffff621ee2b5 CR3: 000000007b91a000 CR4:
>> 00000000000006e0
>> [ 107.420038] Stack:
>> [ 107.420038] 000000000000005f ffffffff813b2b22 0000000000000246
>> 0000000000000001
>> [ 107.420038] 0000000000000000 0000000001e49c20 0000000000000001
>> 0000000000000023
>> [ 107.420038] 00000000000003ff 0000000000628940 0000000000000001
>> 0000000000000001
>> [ 107.420038] Call Trace:
>> [ 107.420038] [<ffffffff813b2b22>] ? system_call_fastpath+0x16/0x1b
>> [ 107.420038] Code: Bad RIP value.
>> [ 107.420038] RIP [<ffffffff621ee2b5>] 0xffffffff621ee2b4
>> [ 107.420038] RSP <ffff88007a05df78>
>> [ 107.420038] CR2: ffffffff621ee2b5
>> [ 107.420038] ---[ end trace fe1cc133ae0119a3 ]---
>>
>> And others.
>>
>>>
>>>
>>> #! /usr/bin/env ktap
>>> trace probe:schedule {
>>> print(backtrace(0, 100))
>>> }
>>
>> This one printed message about 10 tines
>> and after this system hangs.
>>
>> In debugger attached to kernel:
>> Program received signal SIGSEGV, Segmentation fault.
>>
>>
> Thanks. It seems the kernel crash doesn't caused by backtrace(), but
> ktapvm core or kernel side.
Yes, I already test another script (without backtrace), that also have
some problems.
Do you have this issue?
>
> Would you please check below scripts again?
>
> -------------------------------------------------
> #!/usr/bin/env ktap
>
> trace probe:SyS_write {
> print("testing")
> }
page fault.
> --------------------------------------------------
> #!/usr/bin/env ktap
>
> trace probe:SyS_write {
> }
page fault.
> --------------------------------------------------
> #!/usr/bin/env ktap
>
> trace probe:schedule {
> }
Just after this command, I ran dmesg, and received page fault.
And system hanged.
> -------------------------------------------------
> #!/usr/bin/env ktap
>
> trace syscalls:sys_write_enter {
> }
"s/sys_write_enter/sys_enter_write/"
Seems works fine.
> -------------------------------------------------
> ./ktap test/arith.kp
No output. No errors in kern.log
> -------------------------------------------------
>
> And your hardware is x86-64 or ARM-64?
x86-64
>
--
Respectfully
Azat Khuzhin
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