[LU-2419] mdt threads stuck in ldlm_expired_completion_wait

• Type: Bug
• Resolution: Cannot Reproduce
• Priority: Major
• Affects Version/s: Lustre 2.1.2
• Labels: llnl
• Environment: Lustre 2.1.2-3chaos (github.com/chaos/lustre)
• Severity: 3
• Assignee: Alex Zhuravlev
• Reporter: Christopher Morrone (Inactive)

Description

One of our production MDS is in trouble, causing application hangs. It looks like CPU usage is low, but the node has mdt threads hanging for 800+ seconds before timeout. It is frequently printing backtraces like so:

2012-11-30 16:32:02 Lustre: Service thread pid 4557 was inactive for 808.00s. The thread might be hung, or it might only be slow and will resume later. Dumping the stack trace for debugging pur
poses:
2012-11-30 16:32:02 Lustre: Skipped 4 previous similar messages
2012-11-30 16:32:02 Pid: 4557, comm: mdt_294
2012-11-30 16:32:02 
2012-11-30 16:32:02 Call Trace:
2012-11-30 16:32:02  [<ffffffffa071c590>] ? ldlm_expired_completion_wait+0x0/0x270 [ptlrpc]
2012-11-30 16:32:02  [<ffffffffa04913f1>] ? libcfs_debug_vmsg1+0x41/0x50 [libcfs]
2012-11-30 16:32:02  [<ffffffffa071c590>] ? ldlm_expired_completion_wait+0x0/0x270 [ptlrpc]
2012-11-30 16:32:02  [<ffffffffa048854e>] cfs_waitq_wait+0xe/0x10 [libcfs]
2012-11-30 16:32:02  [<ffffffffa071fe6a>] ldlm_completion_ast+0x4da/0x690 [ptlrpc]
2012-11-30 16:32:02  [<ffffffff8105ea30>] ? default_wake_function+0x0/0x20
2012-11-30 16:32:02  [<ffffffffa071f706>] ldlm_cli_enqueue_local+0x1e6/0x470 [ptlrpc]
2012-11-30 16:32:02  [<ffffffffa071f990>] ? ldlm_completion_ast+0x0/0x690 [ptlrpc]
2012-11-30 16:32:02  [<ffffffffa0c59180>] ? mdt_blocking_ast+0x0/0x230 [mdt]
2012-11-30 16:32:02  [<ffffffffa0c5ae5f>] mdt_object_lock+0x28f/0x980 [mdt]
2012-11-30 16:32:02  [<ffffffffa0c59180>] ? mdt_blocking_ast+0x0/0x230 [mdt]
2012-11-30 16:32:02  [<ffffffffa071f990>] ? ldlm_completion_ast+0x0/0x690 [ptlrpc]
2012-11-30 16:32:02  [<ffffffffa0c5b871>] mdt_object_find_lock+0x61/0x100 [mdt]
2012-11-30 16:32:02  [<ffffffffa0c70fe2>] mdt_md_create+0x102/0x5a0 [mdt]
2012-11-30 16:32:02  [<ffffffffa03af96c>] ? lprocfs_counter_add+0x11c/0x190 [lvfs]
2012-11-30 16:32:02  [<ffffffffa0c71598>] mdt_reint_create+0x118/0x5e0 [mdt]
2012-11-30 16:32:02  [<ffffffffa0c6f2d0>] mdt_reint_rec+0x40/0xb0 [mdt]
2012-11-30 16:32:02  [<ffffffffa0740eb4>] ? lustre_msg_get_flags+0x34/0x70 [ptlrpc]
2012-11-30 16:32:02  [<ffffffffa0c6a0c8>] mdt_reint_internal+0x4f8/0x770 [mdt]
2012-11-30 16:32:02  [<ffffffffa0c6a384>] mdt_reint+0x44/0xc0 [mdt]
2012-11-30 16:32:03  [<ffffffffa0c5e79d>] mdt_handle_common+0x73d/0x12c0 [mdt]
2012-11-30 16:32:03  [<ffffffffa0740cc4>] ? lustre_msg_get_transno+0x54/0x90 [ptlrpc]
2012-11-30 16:32:03  [<ffffffffa0c5f3f5>] mdt_regular_handle+0x15/0x20 [mdt]
2012-11-30 16:32:03  [<ffffffffa074cd64>] ptlrpc_main+0xd24/0x1740 [ptlrpc]
2012-11-30 16:32:03  [<ffffffffa074c040>] ? ptlrpc_main+0x0/0x1740 [ptlrpc]
2012-11-30 16:32:03  [<ffffffff8100c14a>] child_rip+0xa/0x20
2012-11-30 16:32:03  [<ffffffffa074c040>] ? ptlrpc_main+0x0/0x1740 [ptlrpc]
2012-11-30 16:32:03  [<ffffffffa074c040>] ? ptlrpc_main+0x0/0x1740 [ptlrpc]
2012-11-30 16:32:03  [<ffffffff8100c140>] ? child_rip+0x0/0x20

See attached file console.momus-mds1.txt for more of the console log, including backtraces from the processes on the system.

Issue Links

• is duplicated by: LU-4572 hung mdt threads
• is related to: LU-2944 Client evictions - watchdog timeouts on MDT - iorfpp