Description of problem:
On a Xen VM running only as a DB server, examining the messages log, the following appeared.

Jun 17 05:01:02 hostname kernel: INFO: task mysqld:24980 blocked for more than 120 seconds.
Jun 17 05:01:02 hostname kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Jun 17 05:01:02 hostname kernel: mysqld        D 0000fefc778b5d89     0 24980   1923         24981 24979 (NOTLB)
Jun 17 05:01:02 hostname kernel:  ffff88013adfbd88  0000000000000282  ffff88013adfbd98  ffffffff80262dd3 
Jun 17 05:01:02 hostname kernel:  0000000000000008  ffff8801ab3b80c0  ffffffff804f4b00  00000000000006cb 
Jun 17 05:01:02 hostname kernel:  ffff8801ab3b82a8  0000000000004c17 
Jun 17 05:01:02 hostname kernel: Call Trace:
Jun 17 05:01:02 hostname kernel:  [<ffffffff80262dd3>] thread_return+0x6c/0x113
Jun 17 05:01:02 hostname kernel:  [<ffffffff88036d5a>] :jbd:log_wait_commit+0xa3/0xf5
Jun 17 05:01:02 hostname kernel:  [<ffffffff8029c521>] autoremove_wake_function+0x0/0x2e
Jun 17 05:01:02 hostname kernel:  [<ffffffff8803178a>] :jbd:journal_stop+0x1cf/0x1ff
Jun 17 05:01:02 hostname kernel:  [<ffffffff80231056>] __writeback_single_inode+0x1e9/0x328
Jun 17 05:01:02 hostname kernel:  [<ffffffff802e5775>] sync_inode+0x24/0x33
Jun 17 05:01:04 hostname kernel:  [<ffffffff8804c36d>] :ext3:ext3_sync_file+0xc9/0xdc
Jun 17 05:01:04 hostname kernel:  [<ffffffff80251f3f>] do_fsync+0x52/0xa4
Jun 17 05:01:05 hostname kernel:  [<ffffffff802d370c>] __do_fsync+0x23/0x36
Jun 17 05:01:05 hostname kernel:  [<ffffffff802602f9>] tracesys+0xab/0xb6



Version-Release number of selected component (if applicable):
mysql-5.0.77-4.el5_5.3
mysql-server-5.0.77-4.el5_5.3


Additional info:

If this log means a high load case. During this time, there was nothing noticed to cause any high load, however under high load previously it didn't behave like that.

Probably Related bugs:
https://bugzilla.redhat.com/show_bug.cgi?id=592049