[OpenAFS-devel] question: binary interface to kernel module (RHEL6.2/6.3, openafs 1.6.1)?

[Stephan Wiesand]

On Aug 30, 2012, at 18:51 , Andrew Deason <adeason@sinenomine.net> =
wrote:

> On Thu, 30 Aug 2012 15:19:16 +0200
> Stephan Wiesand <stephan.wiesand@desy.de> wrote:
>=20
>> I fstraced a read getting stuck. This is what it looks like:
>=20
> What about a kernel stack trace? Could you get one with 'crash', or at
> least 'echo t > /proc/sysrq-trigger' ? In crash it would just be like
> 'set 1234' and 'bt', iirc, where 1234 is the pid of a hanging proc.

I'm afraid Simon is right about all this. I'm still curious though, so I =
tried the crash exercise (sysrq looks similar):

crash> set 4479
    PID: 4479
COMMAND: "cfagent"
   TASK: c24d2000  [THREAD_INFO: eb4a4000]
    CPU: 0
  STATE: (unknown)=20
crash> bt
PID: 4479   TASK: c24d2000  CPU: 0   COMMAND: "cfagent"
 #0 [eb4a5ce4] schedule at c083c6a3
 #1 [eb4a5da8] io_schedule at c083ce34
 #2 [eb4a5db4] sync_page at c04e0e57
 #3 [eb4a5db8] sync_page_killable at c04e0e70
 #4 [eb4a5dbc] __wait_on_bit_lock at c083d50b
 #5 [eb4a5dd8] __lock_page_killable at c04e0d7b
 #6 [eb4a5e00] generic_file_aio_read at c04e2608
 #7 [eb4a5e78] do_sync_read at c052d3b2
 #8 [eb4a5f20] afs_linux_read at edaef53b [openafs]
 #9 [eb4a5f74] vfs_read at c052de3b
#10 [eb4a5f94] sys_read at c052df6c
#11 [eb4a5fb0] system_call at c083ec8d
    EAX: ffffffda  EBX: 00000003  ECX: b77c1000  EDX: 00001000=20
    DS:  007b      ESI: 09b38420  ES:  007b      EDI: 00000400
    SS:  007b      ESP: bf8f6c84  EBP: bf8f6cb4  GS:  0033
    CS:  0073      EIP: 00fd5416  ERR: 00000003  EFLAGS: 00200246=20

But unless this gets us somewhere soon, I'm not planning to do much more =
research on this issue.

Thanks again for all the feedback.
	Stephan

--=20
Stephan Wiesand
DESY - DV -
Platanenallee 6
15732 Zeuthen, Germany