[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: Mon, 21 Oct 2013 09:15:46 +0400
On Mon, Oct 21, 2013 at 7:55 AM, Jovi Zhangwei <jovi.zhangwei@xxxxxxxxx> wrote:
> On Mon, Oct 21, 2013 at 12:01 AM, Azat Khuzhin <a3at.mail@xxxxxxxxx> wrote:
>> 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
>>
> Unfortunately I cannot reproduce the crash in my local x86-64
> box(whatever any kernel version, include 3.12-rc6).
>
> Things to be clear now, kernel will crash only using ktap kprobe,
> tracepoint and other ktap basic operation is fine.
> It have a little strange that actually ktapvm doesn't know tracepoint
> or kprobe in kernel side, ktapvm just treat them as a id,
> so it's weird that tracepoint is fine but kprobe is not working.
>
> I guess you ran vanilla kernel (3.12-rc6) with no additional patch,
> could you post your kernel config file?
Yes, it is vanilla kernel, but with some debug patches.
(printk's, and one patch to btrfs, I don't think that this actually
play some role)
I will try to reproduce this issue using the latest tar balls version
tomorrow (I hope).
Here is my kernel config
https://gist.github.com/azat/7078890
Thanks!
> then I can try to reproduce it in my box.
>
> Thank you.
>
> Jovi
>
--
Respectfully
Azat Khuzhin
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