strange Bug

ba_f ba_f at rbg.informatik.tu-darmstadt.de
Sat Nov 15 15:47:00 CET 2014


Hello again,

and thanks to Martin.


> * At the time of the page fault you end up in the kernel debugger.
>   Use 'lp' to see the list of present threads.

Alright, let's see:

     
---------------------------------------------------------------------
     CPU 0 [f002e898]: IRQ ENTRY
     CPU(s) 0-1 entered JDB
jdb: l
    id  cpu    name             pr     sp  wait    to state
    6e   0     &-                2     58     -       rcv_wait
    6b   0     -----            10     58     -       rcv_wait
    62   0     &-                2     49     -       rcv_wait
    60   0     -----             2     58    6e       rcv_wait,exc_progr
    5c   0     -----            10     49     -       rcv_wait
    59   0     #myClient        ff     58     -       rcv_wait
    4d   0     -----             2     49     -       rcv_wait,fpu
    4a   0     #myServer        ff     49     -       rcv_wait
    40   0     -----             2     31     -       rcv_wait
    3d   0     -----            10     31     -       rcv_wait
    35   0     -----             2     31    35       rcv_wait
    32   0     #ned             ff     31     -       rcv_wait
     c   1     -----             0      1             ready
     a   0     moe              ff      9     -       rcv_wait
     8   0     sigma0            1      7     -       rcv_wait
     6   0     -----             0      1             ready

>   One of them will be the one that is in the debugger now.
>   It should be one of the L4Re threads
>   (those have names starting with # in the thread list).

Is it thread 60 with 'exc_progr'?
Or one of the 'ready' threads?

>   What is this thread's state (command 't<id>')? At what instruction
>   is the thread stuck?

  jdb: t60
   thread  :  60 <0xf1195000>      CPU: 0:0        prio: 02  mode: Con
   state   : 40008 rcv_wait,exc_progr
   wait for:   6e  polling:        rcv descr: 00000000
   lcked by:                       timeout  :
   cpu time:  21.000 ms            timeslice: 8000/-1 �s
   pager   : [C:   3] D:  59       task     : D:  58
   exc-hndl: [C: 415] D:  6e       UTCB     : f118a200/b3000200
   vCPU    : ---
   vCPU    : ---

   PC=0015c7a8 USP=7ffff2f8
   [0] 000a4a0c 00091f5c 0000050c 00025848 [4] 00031c20 ffffdabc 000aea70 
00000001
   [8] 80003e64 00091f5c 00000000 00000000 [c] 000ae9b8 0007cb14 004094b4 
60000010


At least this thread has the PC of the Error-Message:

   myClient| L4Re[rm]: unhandled write page fault @7ffff2e0 pc=15c7a8
   myClient| No signal handler found


Well, is this the bad guy?
If so, then where does it come from?
And what to check next?


Greetings,
ba_f




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