[Thinlinc-technical] Kernel panic with Ubuntu 12.10 and mounting/unmounting USB drives with thinlinc

Jens Langner j.langner at hzdr.de
Wed Jul 10 17:25:55 CEST 2013 

Hi Peter,

For the client we are using the latest 'thinstation' version available at the corresponding git. In fact it uses kernel 3.9.4 (32bit). Our ThinLinc server uses currently 3.5.0-36-generic (64bit) and the problem is still present. Our ThinLinc client on our thinstation is the latest 4.1.0 rev 3996. And do you really think that the client OS version really depends on seeing the server side crashing when doing a tl-mount-localdrives? I highly doubt that. IMHO this seems to be a kernel bug in 3.5.0. Unfortunately I can't test the latest 13.04 ubuntu version with kernel 3.8.0 because that comes with another bug that strikes us as ldap authentication (nss_ldap) doesn't work and thus thinlinc won't work with 13.04 as well. This however might not be a general problem for everyone but related to our quite large ldap directory here which might trigger the problem somehow.

And we are using 12.10 because we always need/want the latest tools to be available to us and not having to wait 2 years for a new LTS release to appear. That's why we also would love to upgrade to 13.04 but unfortunately the mentioned LDAP problem currently prevents us from doing so (see here form more: https://bugs.launchpad.net/ubuntu/+source/libnss-ldap/+bug/1185699)

Any help would be appreciated in trying to get at least the tl-mount-localdrives crash problem being resolved. Unfortunately I doubt that reporting this Canonical will help as my experience in reporting bugs in the hope they are fixed by Canonical are more than worse :(

best regards,
jens

Am 10.07.2013 um 17:09 schrieb Peter Åstrand <astrand at cendio.se>:

> Thanks for the update. I tried to reproduce the problem with a 32-bit 12.10 server, but was not successful. Perhaps it depends on the client as well. Which versions of things (OS, TL client) are you running at the client?
> 
> Also, I believe there's a slightly later kernel now, 3.5.0-36-generic or so. Would be great if you could verify if the problem exists in that version as well.
> 
> Btw, any particular reason why are using the non-LTS 12.10 release instead of the recommended 12.04?
> 
> Rgds,
> Peter
> 
> On Wed, 10 Jul 2013, Jens Langner wrote:
> 
>> Unfortunately it is the kernel on the server that crashes. And it is the standard 64bit kernel of Ubuntu 12.10.
>> 
>> These crashes are actually the reason why we currently refrain from mounting and local drives (USB) completely or otherwise our whole ThinLinc server will crash.
>> 
>> best regards,
>> jens
>> 
>> Am 10.07.2013 um 15:52 schrieb Peter Astrand <astrand at cendio.se>:
>> 
>>> Is it the kernel on the client or the server that crashes? Is it a 32- or 64-bit system?
>>> 
>>> Regards,
>>> Peter
>>> 
>>>> 
>>>> 
>>>> Hello,
>>>> 
>>>> recently we are excessively testing the mounting and unmounting of USB devices through ThinLinc and have came across a problem that seems to prevent us from using the functionality to mount local drives with thinlinc. In fact, what our users are doing are that they insert a USB thumb drive into our Thinclient (NUC). Then they use the tl-mount-localdrives command. Afterwards they "cd" into the corresponding directory, do something and unmount it afterwards using tl-umount-localdrives. This procedure is repeated several times. Unfortunately there seems to be a problem at least with the kernels supplied with ubuntu 12.10 as they seem to crash badly as you can see by the attached crash log.
>>>> 
>>>> I am now of course curious if this problem is known, if there exists a workaround or did anyone run into the same problems yet? As said, this behavior currently prevents us from using the local drives mount functionality of thinlinc which we would really love to have.
>>>> 
>>>> best regards,
>>>> jens
>>>> 
>>>> -- cut here --
>>>> Jul  4 09:52:35 saturn kernel: [156591.684621] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
>>>> Jul  4 09:52:35 saturn kernel: [156591.684659] IP: [<ffffffff811a0062>] commit_tree+0x82/0x100
>>>> Jul  4 09:52:35 saturn kernel: [156591.684686] PGD 78da91067 PUD 78da90067 PMD 0 Jul  4 09:52:35 saturn kernel: [156591.684720] Oops: 0000 [#1] SMP Jul  4 09:52:35 saturn kernel: [156591.684744] CPU 50 Jul  4 09:52:35 saturn kernel: [156591.684751] Modules linked in: ipmi_devintf ipmi_si ipmi_msghandler autofs4 parport_pc ppdev binfmt_misc kvm_amd kvm ghash
>>>> _clmulni_intel aesni_intel cryptd aes_x86_64 sp5100_tco microcode psmouse serio_raw joydev amd64_edac_mod fam15h_power k10temp edac_core edac_mce_amd i2c_pii
>>>> x4 bnep rfcomm bluetooth mac_hid w83795 w83627ehf hwmon_vid nfsd lp parport nfs lockd fscache auth_rpcgss nfs_acl sunrpc hid_generic usbhid hid pata_atiixp a
>>>> hci qla2xxx igb libahci dca scsi_transport_fc megaraid_sas scsi_tgt usb_storage
>>>> Jul  4 09:52:35 saturn kernel: [156591.685081] Jul  4 09:52:35 saturn kernel: [156591.685089] Pid: 10693, comm: bash Not tainted 3.5.0-34-generic #55-Ubuntu Supermicro H8QG6/H8QG6
>>>> Jul  4 09:52:35 saturn kernel: [156591.685133] RIP: 0010:[<ffffffff811a0062>]  [<ffffffff811a0062>] commit_tree+0x82/0x100
>>>> Jul  4 09:52:35 saturn kernel: [156591.685159] RSP: 0018:ffff881a57971bb8  EFLAGS: 00010212
>>>> Jul  4 09:52:35 saturn kernel: [156591.685176] RAX: ffff881a57971b38 RBX: ffff881a57971bf8 RCX: ffff881a57971bb8
>>>> Jul  4 09:52:35 saturn kernel: [156591.685265] RDX: ffff881bc5c2dd80 RSI: ffff881bc5c2dd00 RDI: 0000000000000000
>>>> Jul  4 09:52:35 saturn kernel: [156591.685345] RBP: ffff881a57971bc8 R08: ffff882006d09e00 R09: 0000000000000100
>>>> Jul  4 09:52:35 saturn kernel: [156591.685426] R10: ffffea00203fe780 R11: ffffffffa01c9b00 R12: ffff881bc5c2dd00
>>>> Jul  4 09:52:35 saturn kernel: [156591.685521] R13: 0000000000000000 R14: ffff881a57971dd8 R15: ffff882006d09e20
>>>> Jul  4 09:52:35 saturn kernel: [156591.685603] FS:  00007faefd820700(0000) GS:ffff881c17c80000(0000) knlGS:00000000e72ffb40
>>>> Jul  4 09:52:35 saturn kernel: [156591.685688] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>> Jul  4 09:52:35 saturn kernel: [156591.685738] CR2: 0000000000000018 CR3: 000000078d908000 CR4: 00000000000407e0
>>>> Jul  4 09:52:35 saturn kernel: [156591.685821] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>>> Jul  4 09:52:35 saturn kernel: [156591.685906] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
>>>> Jul  4 09:52:35 saturn kernel: [156591.685987] Process bash (pid: 10693, threadinfo ffff881a57970000, task ffff881b6565c500)
>>>> Jul  4 09:52:35 saturn kernel: [156591.686071] Stack:
>>>> Jul  4 09:52:35 saturn kernel: [156591.686108]  ffff881bc5c2dd80 ffff881bc5c2dd80 ffff881a57971c38 ffffffff811a1838
>>>> Jul  4 09:52:35 saturn kernel: [156591.686227]  ffff881a57971be8 0000000000000000 ffff882006d09e00 ffff88040ff12b40
>>>> Jul  4 09:52:35 saturn kernel: [156591.686331]  ffff881a57971bf8 ffff881a57971bf8 ffff881a57971c48 ffff881a57971dd8
>>>> Jul  4 09:52:35 saturn kernel: [156591.686433] Call Trace:
>>>> Jul  4 09:52:35 saturn kernel: [156591.686482]  [<ffffffff811a1838>] attach_recursive_mnt+0x1b8/0x1c0
>>>> Jul  4 09:52:35 saturn kernel: [156591.686542]  [<ffffffff811a1895>] graft_tree+0x55/0x90
>>>> Jul  4 09:52:35 saturn kernel: [156591.686598]  [<ffffffff811a198f>] do_add_mount+0xbf/0xe0
>>>> Jul  4 09:52:35 saturn kernel: [156591.686654]  [<ffffffff811a0e8d>] ? mnt_get_count+0x4d/0x70
>>>> Jul  4 09:52:35 saturn kernel: [156591.686726]  [<ffffffff811a2507>] finish_automount+0x57/0xf0
>>>> Jul  4 09:52:35 saturn kernel: [156591.686784]  [<ffffffff8118dbee>] follow_managed+0x1ae/0x2d0
>>>> Jul  4 09:52:35 saturn kernel: [156591.686841]  [<ffffffff8118f661>] lookup_fast+0x1c1/0x310
>>>> Jul  4 09:52:35 saturn kernel: [156591.686899]  [<ffffffff8119132c>] path_lookupat+0x11c/0x720
>>>> Jul  4 09:52:35 saturn kernel: [156591.686956]  [<ffffffff8118d653>] ? putname+0x33/0x50
>>>> Jul  4 09:52:35 saturn kernel: [156591.687011]  [<ffffffff811924d8>] ? user_path_at_empty+0x68/0xa0
>>>> Jul  4 09:52:35 saturn kernel: [156591.687073]  [<ffffffff8116e681>] ? kmem_cache_alloc+0x31/0x130
>>>> Jul  4 09:52:35 saturn kernel: [156591.687131]  [<ffffffff81191961>] do_path_lookup+0x31/0xc0
>>>> Jul  4 09:52:35 saturn kernel: [156591.687187]  [<ffffffff8118d563>] ? getname_flags+0x53/0xf0
>>>> Jul  4 09:52:35 saturn kernel: [156591.687244]  [<ffffffff811924cd>] user_path_at_empty+0x5d/0xa0
>>>> Jul  4 09:52:35 saturn kernel: [156591.687304]  [<ffffffff811875bb>] ? vfs_stat+0x1b/0x20
>>>> Jul  4 09:52:35 saturn kernel: [156591.687360]  [<ffffffff811877ea>] ? sys_newstat+0x1a/0x40
>>>> Jul  4 09:52:35 saturn kernel: [156591.687416]  [<ffffffff81192521>] user_path_at+0x11/0x20
>>>> Jul  4 09:52:35 saturn kernel: [156591.687473]  [<ffffffff81181853>] sys_chdir+0x23/0x90
>>>> Jul  4 09:52:35 saturn kernel: [156591.687532]  [<ffffffff8168a429>] system_call_fastpath+0x16/0x1b
>>>> Jul  4 09:52:35 saturn kernel: [156591.687584] Code: 48 8d 42 80 74 22 0f 1f 00 48 89 b8 d8 00 00 00 f0 ff 40 40 48 8b 90 80 00 00 00 48 39 ca 48 8d 42 80 75
>>>> e5 48 8b 55 f0 48 39 ca <48> 8b 47 18 74 15 48 8b 08 4c 8b 4d f8 48 89 42 08 48 89 10 49 Jul  4 09:52:35 saturn kernel: [156591.687977] RIP  [<ffffffff811a0062>] commit_tree+0x82/0x100
>>>> Jul  4 09:52:35 saturn kernel: [156591.688030]  RSP <ffff881a57971bb8>
>>>> Jul  4 09:52:35 saturn kernel: [156591.688072] CR2: 0000000000000018
>>>> Jul  4 09:52:35 saturn kernel: [156591.688564] ---[ end trace cc8c3aa8321f8b62 ]---
>>>> -- cut here --
>> 
>> 
>> 
>> -- 
>> Dr. Jens Langner
>> Helmholtz-Zentrum Dresden-Rossendorf
>> Institute of Radiopharmaceutical Cancer Research
>> Department of Positron Emission Tomography
>> POB 51 01 19, 01314 Dresden, Germany
>> http://www.hzdr.de/ | +49 351 260 2757
>> 
>> Vorstand: Prof. Dr. Dr. h. c. Roland Sauerbrey
>> Prof. Dr. Dr. h. c. Peter Joehnk
>> VR 1693 beim Amtsgericht Dresden



-- 
Dr. Jens Langner
Helmholtz-Zentrum Dresden-Rossendorf
Institute of Radiopharmaceutical Cancer Research
Department of Positron Emission Tomography
POB 51 01 19, 01314 Dresden, Germany
http://www.hzdr.de/ | +49 351 260 2757

Vorstand: Prof. Dr. Dr. h. c. Roland Sauerbrey
Prof. Dr. Dr. h. c. Peter Joehnk
VR 1693 beim Amtsgericht Dresden


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