sched lock/sleepq lock order reversal

Scott Sipe cscotts at
Sat Apr 10 04:34:14 PDT 2004

I apologize in advance if this is a known ok LOR--I tried searching for 
past mention of it and couldn't find it though.

Computer is running CURRENT from around March 28.  It hard freezes on a 
fairly regular basis, generally when being accessed by NFS or Samba, and 
I saw this LOR show up (it's still running fine) after I attached a 
serial console to try to figure out the problem (it's headless).

I'll provide any extra information if anyone needs it.

here it is:

lock order reversal
   1st 0xc0750860 sched lock (sched lock) @ 
   2nd 0xc07535a4 sleepq chain (sleepq chain) @ 
  Stack backtrace:
  backtrace(c06f5338,c07535a4,c06f468c,c06f468c,c06f4699) at backtrace+0x17
  witness_checkorder(c07535a4,9,c06f4699,c1,c0755c20) at 
  _mtx_lock_spin_flags(c07535a4,0,c06f4699,c1,c47f1c08) at 
  sleepq_lookup(c47f1000,0,c0750860,c07577e0,c47f1c08) at sleepq_lookup+0x67
  sleepq_broadcast(c47f1000,0,ffffffff,dcf15c54,c052881a) at 
  wakeup(c47f1000,1,c06f1def,8b8,c47f1c08) at wakeup+0x21
  stop(c47f1c08,0,c06f1def,7ed,178) at stop+0x4a
  ptracestop(c46ed540,5,c06f1def,82f,10) at ptracestop+0xde
  issignal(c46ed540,2,c06f1def,be,0) at issignal+0x207
  cursig(c46ed540,0,c06f4acd,102,30800) at cursig+0xe8
  ast(dcf15d48) at ast+0x510
  doreti_ast() at doreti_ast+0x17


uname -a
FreeBSD 5.2-CURRENT FreeBSD 5.2-CURRENT #5: Sun 
Mar 28 19:35:37 EST 2004 
root at  i386

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