[Samba] An incomprehensible error "Kernel oplock message announced, but none received"

[ITPFS oota]

The following messages were displayed on the log of Samba. 

 [2010/xx/yy 01:23:45, 3] smbd/oplock.c:process_kernel_oplocks(85)
  Kernel oplock message announced, but none received

What reason is this message displayed? 

--
--- Oota Toshiya ---  t-oota at dh.jp.nec.com
NEC Systems Software Operations Unit      Shiba,Minato,Tokyo
IT Platform Solutions Division            Japan,Earth,Solar system
(samba-jp/ldap-jp Staff,mutt-j/samba-jp postmaster)