OS rebooted due to os stall.

Issue

• Our customer encountered an unexpected reboot problem.
• From our investigation, we found a kernl panic occurred at that time and the panic was caused due to timeout of a timer monitoring by clusterpro software. The timeout occurs if cluserpro-related process, which runs the timer monitoring, stalls.
• According to our vmcore analysis, several processes were waiting I/O. Perhaps, the clusterpro-related process became unable to work and reached timeout of the timer monitoring. System processes such as kjounald and pdflush were waiting I/O?
• Process lists which ST is 'UN'

     PID    PPID  CPU       TASK        ST  %MEM     VSZ    RSS  COMM
      645     83   1  ffff81023dcff7e0  UN   0.0       0      0  [kjournald]
     3297     83   1  ffff8101b6c8c7a0  UN   0.0       0      0  [pdflush]
     3426     83   1  ffff81008875e100  UN   0.0       0      0  [pdflush]
     5083      1   0  ffff81023bbe3080  UN   0.0    5904    696  syslogd
     6219   6218   1  ffff810232cbe0c0  UN   0.0   23824   1780  clpevent
    16845  16840   0  ffff8100850987e0  UN   0.0    3844    616  sadc
    29187  29183   1  ffff810110d3a0c0  UN   0.0   29696   4628  actlog_cpuload
                                        ^^