khugepaged プロセスがセマフォロックの取得を待機中に khungtaskd が原因でカーネルパニックが発生する

Issue

• 以下の呼び出しトレースによって、カーネルパニックが発生します。

INFO: task khugepaged:60 blocked for more than 120 seconds.
echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
khugepaged    D 0000000000000003     0    60      2 0x00000000
 ffff880631f59c88 0000000000000046 0000000000000000 ffff880631f59c10
 ffff880028396700 0000000000000000 0000000000000000 0000000000016700
 ffff880631f0e5f8 ffff880631f59fd8 000000000000fb88 ffff880631f0e5f8
Call Trace:
 [<ffffffff810096f0>] ? __switch_to+0xd0/0x320
 [<ffffffff810810cc>] ? lock_timer_base+0x3c/0x70
 [<ffffffff81510695>] rwsem_down_failed_common+0x95/0x1d0
 [<ffffffff81510826>] rwsem_down_read_failed+0x26/0x30
 [<ffffffff810811e0>] ? process_timeout+0x0/0x10
 [<ffffffff81283844>] call_rwsem_down_read_failed+0x14/0x30
 [<ffffffff8150fd24>] ? down_read+0x24/0x30
 [<ffffffff81179c1f>] khugepaged+0x18f/0x1310
 [<ffffffff81096da0>] ? autoremove_wake_function+0x0/0x40
 [<ffffffff81179a90>] ? khugepaged+0x0/0x1310
 [<ffffffff81096a36>] kthread+0x96/0xa0
 [<ffffffff8100c0ca>] child_rip+0xa/0x20
 [<ffffffff810969a0>] ? kthread+0x0/0xa0
 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20
Kernel panic - not syncing: hung_task: blocked tasks
Pid: 57, comm: khungtaskd Tainted: P           ---------------    2.6.32-358.18.1.el6.x86_64 #1
Call Trace:
 [<ffffffff8150da18>] ? panic+0xa7/0x16f
 [<ffffffff810e0bd7>] ? watchdog+0x217/0x220
 [<ffffffff810e09c0>] ? watchdog+0x0/0x220
 [<ffffffff81096a36>] ? kthread+0x96/0xa0
 [<ffffffff8100c0ca>] ? child_rip+0xa/0x20
 [<ffffffff810969a0>] ? kthread+0x0/0xa0
 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20