Ocfs2 devel - May 2015 - Could someone tell me the function of LVB, thanks

Hi all,
    In my 10 nodes cluster, I find some strange logs in kernel.log when
operating some days. logs as follws:

May 14 14:01:33 cvk68 kernel: [272684.537063]
(umount,52420,10):dlm_prepare_lvb_for_migration:1216 ERROR: Mismatched lvb in
lock cookie=8:982, name=M00000000000000007e012000000000, node=8 May 14 14:01:33
cvk68 kernel: [272684.537066] lockres: M00000000000000007e012000000000, owner=6,
state=32
May 14 14:01:33 cvk68 kernel: [272684.537067]   last used: 0, refcnt: 11, on
purge list: no
May 14 14:01:33 cvk68 kernel: [272684.537068]   on dirty list: no, on reco list:
no, migrating pending: no
May 14 14:01:33 cvk68 kernel: [272684.537069]   inflight locks: 0, asts
reserved: 0
May 14 14:01:33 cvk68 kernel: [272684.537069]   refmap nodes: [ 1 2 3 4 5 7 8 9
10 ], inflight=0
May 14 14:01:33 cvk68 kernel: [272684.537073]   granted queue:
May 14 14:01:33 cvk68 kernel: [272684.537074]     type=3, conv=-1, node=2,
cookie=2:949, ref=2, ast=(empty=y,pend=n), bast=(empty=y,pend=n),
pending=(conv=n,lock=n,cancel=n,unlock=n)
May 14 14:01:33 cvk68 kernel: [272684.537075]
050000000000005900000000000000001554ffffffc162ffffffec2a26ffffffd41554ffffffc162ffffffeaffffffbbfffffff0ffffffd41554ffffffc162ffffffeaffffffbbfffffff0ffffffd40000000005ffffffa00000ffffff81ffffff800001000000006d16ffffffc96400000000
May 14 14:01:33 cvk68 kernel: [272684.537092]     type=3, conv=-1, node=5,
cookie=5:1103, ref=2, ast=(empty=y,pend=n), bast=(empty=y,pend=n),
pending=(conv=n,lock=n,cancel=n,unlock=n)
May 14 14:01:33 cvk68 kernel: [272684.537094]     type=3, conv=-1, node=4,
cookie=4:1117, ref=2, ast=(empty=y,pend=n), bast=(empty=y,pend=n),
pending=(conv=n,lock=n,cancel=n,unlock=n)
May 14 14:01:33 cvk68 kernel: [272684.537095]     type=3, conv=-1, node=1,
cookie=1:987, ref=2, ast=(empty=y,pend=n), bast=(empty=y,pend=n),
pending=(conv=n,lock=n,cancel=n,unlock=n)
May 14 14:01:33 cvk68 kernel: [272684.537096]     type=3, conv=-1, node=7,
cookie=7:973, ref=2, ast=(empty=y,pend=n), bast=(empty=y,pend=n),
pending=(conv=n,lock=n,cancel=n,unlock=n)
May 14 14:01:33 cvk68 kernel: [272684.537097]
050000000000005900000000000000001554ffffffc162ffffffec2a26ffffffd41554ffffffc162ffffffeaffffffbbfffffff0ffffffd41554ffffffc162ffffffeaffffffbbfffffff0ffffffd40000000005ffffffa00000ffffff81ffffff800001000000006d16ffffffc96400000000
May 14 14:01:33 cvk68 kernel: [272684.537114]     type=3, conv=-1, node=8,
cookie=8:982, ref=2, ast=(empty=y,pend=n), bast=(empty=y,pend=n),
pending=(conv=n,lock=n,cancel=n,unlock=n)
May 14 14:01:33 cvk68 kernel: [272684.537116]     type=3, conv=-1, node=10,
cookie=10:632, ref=2, ast=(empty=y,pend=n), bast=(empty=y,pend=n),
pending=(conv=n,lock=n,cancel=n,unlock=n)
May 14 14:01:33 cvk68 kernel: [272684.537117]
050000000000005900000000000000001554ffffffc162ffffffec2a26ffffffd41554ffffffc162ffffffeaffffffbbfffffff0ffffffd41554ffffffc162ffffffeaffffffbbfffffff0ffffffd40000000005ffffffa00000ffffff81ffffff800001000000006d16ffffffc96400000000
May 14 14:01:33 cvk68 kernel: [272684.537135]     type=3, conv=-1, node=3,
cookie=3:988, ref=2, ast=(empty=y,pend=n), bast=(empty=y,pend=n),
pending=(conv=n,lock=n,cancel=n,unlock=n)
May 14 14:01:33 cvk68 kernel: [272684.537136]     type=3, conv=-1, node=9,
cookie=9:399, ref=2, ast=(empty=y,pend=n), bast=(empty=y,pend=n),
pending=(conv=n,lock=n,cancel=n,unlock=n)
May 14 14:01:33 cvk68 kernel: [272684.537137]
050000000000005900000000000000001554ffffffc162ffffffec2a26ffffffd41554ffffffc162ffffffeaffffffbbfffffff0ffffffd41554ffffffc162ffffffeaffffffbbfffffff0ffffffd40000000005ffffffa00000ffffff81ffffff800001000000006d16ffffffc96400000000
May 14 14:01:33 cvk68 kernel: [272684.537154]   converting queue:
May 14 14:01:33 cvk68 kernel: [272684.537154]   blocked queue:

This seems nodes [ 2 7 9 10 ] have lvb value, but nodes [ 1 3 4 5 8 ] don't
have.
So, my question is:
1, What is the function of LVB ?
2, In which case this issue occurs?
3, If the value of LVB is meaningless, could we do not compare them between
different nodes?

Thanks!

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