kern/38246: another simple_lock deadlock in netbsd-4, possibly scheduler related (sa_switch(2073.2): no upcall data.)

["Greg A. Woods" <woods%planix.com@localhost>]

>Number:         38246
>Category:       kern
>Synopsis:       another kernel deadlock in netbsd-4, possibly scheduler 
>related (sa_switch(2073.2): no upcall data.)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Mar 16 16:30:00 +0000 2008
>Originator:     Greg A. Woods
>Release:        NetBSD 4.0_STABLE netbsd-4 2008/03/03
>Organization:
Planix, Inc.; Toronto, Ontario; Canada
>Environment:
System: NetBSD 4.0_STABLE GENERIC.MP with -DLOCKDEBUG
Architecture: i386
Machine: i386
>Description:


[Sat Mar 15 05:01:23 2008]sa_switch(2073.2): no upcall data.
[Sat Mar 15 05:01:23 2008]sched_lock lock held
[Sat Mar 15 05:01:23 2008]
[Sat Mar 15 05:01:23 2008]lock heldlock: 0xc09de194, currently at: 
/rest/work/woods/m-NetBSD-4/sys/kern/kern_synch.c:764
[Sat Mar 15 05:01:23 2008]on CPU 0
[Sat Mar 15 05:01:23 2008]last locked: 
/rest/work/woods/m-NetBSD-4/sys/kern/kern_synch.c:497
[Sat Mar 15 05:01:23 2008]last unlocked: 
/rest/work/woods/m-NetBSD-4/sys/kern/kern_sa.c:1466
[Sat Mar 15 05:01:23 
2008]_prop_array_pool(772f6b72,73646f6f,4e2d6d2f,53427465,2f342d44) at 
0xc5e9ce6c
[Sat Mar 15 05:01:23 2008]Stopped in pid 2073.2 (apcupsd) at      
netbsd:cpu_Debugger+0x4:        popl    %ebp
[Sat Mar 15 05:01:23 2008]db{0}> 
[Sun Mar 16 11:39:33 2008]db{0}> trace
[Sun Mar 16 11:39:36 2008]cpu_Debugger(d95456f4,1,ffff,c095b5c7,c041cfe0) at 
netbsd:cpu_Debugger+0x4
[Sun Mar 16 11:39:36 
2008]_simple_lock_assert_unlocked(c09de194,c093178f,c0989310,2fc,596) at 
netbsd:_simple_lock_assert_unlocked+0x135
[Sun Mar 16 11:39:36 2008]wakeup(c5e9ce6c,c09875cc,4eb,d9545780,0) at 
netbsd:wakeup+0x32
[Sun Mar 16 11:39:36 2008]knote_enqueue(c5e9de58,0,d95457cc,c03c87d9,c) at 
netbsd:knote_enqueue+0x1ae
[Sun Mar 16 11:39:36 2008]knote(c0a6dfd0,0,32373032,c,d9668018) at 
netbsd:knote+0x42
[Sun Mar 16 11:39:36 2008]logwakeup(c0988f88,5,0,0,d95457d0) at 
netbsd:logwakeup+0x34
[Sun Mar 16 11:39:36 2008]printf(c0988f88,819,2,3a7,c0a564d0) at 
netbsd:printf+0xc5
[Sun Mar 16 11:39:36 2008]sa_switch(d93f6208,0,2,238,d967aa84) at 
netbsd:sa_switch+0x3eb
[Sun Mar 16 11:39:36 2008]ltsleep(f16937f4,14,c0934845,0,f16937f4) at 
netbsd:ltsleep+0x45f
[Sun Mar 16 11:39:36 2008]acquire(0,600,c048bff5,819,2) at netbsd:acquire+0x133
[Sun Mar 16 11:39:36 2008]_lockmgr(f16937f4,10002,f1693768,c098d3e8,135) at 
netbsd:_lockmgr+0x7fd
[Sun Mar 16 11:39:36 2008]genfs_lock(d9545910,2b4,0,c07c5c00,f1693768) at 
netbsd:genfs_lock+0x35
[Sun Mar 16 11:39:36 2008]VOP_LOCK(f1693768,10002,2b4,246,1) at 
netbsd:VOP_LOCK+0x25
[Sun Mar 16 11:39:36 2008]vn_lock(f1693768,2,f1,e4d12a54,e4d12a54) at 
netbsd:vn_lock+0x9f
[Sun Mar 16 11:39:36 
2008]cache_lookup(e4d12a54,d9545bd8,d9545bec,d93f6208,d0031ce8) at 
netbsd:cache_lookup+0x260
[Sun Mar 16 11:39:36 2008]ufs_lookup(d9545a5c,0,c07c54c0,e4d12a54,d9545bd8) at 
netbsd:ufs_lookup+0xdf
[Sun Mar 16 11:39:36 
2008]VOP_LOOKUP(e4d12a54,d9545bd8,d9545bec,c048aae5,d9545a90) at 
netbsd:VOP_LOOKUP+0x2b
[Sun Mar 16 11:39:36 2008]lookup(d9545bc8,20002,400,d9545be0,2) at 
netbsd:lookup+0x1fb
[Sun Mar 16 11:39:36 2008]namei(d9545bc8,0,575f8791,575f878d,c0a26880) at 
netbsd:namei+0x128
[Sun Mar 16 11:39:36 2008]sys___stat30(d93f6208,d9545c48,d9545c68,0,d9545c40) 
at netbsd:sys___stat30+0x46
[Sun Mar 16 11:39:36 2008]syscall_plain() at netbsd:syscall_plain+0x1a8
[Sun Mar 16 11:39:36 2008]--- syscall (number 387) ---
[Sun Mar 16 11:39:36 2008]0x8117143:
[Sun Mar 16 11:39:36 2008]db{0}> call simple_lock_dump
[Sun Mar 16 11:39:44 2008]all simple locks:
[Sun Mar 16 11:39:44 2008]0xc0a6b854 CPU 0 
/rest/work/woods/m-NetBSD-4/sys/kern/kern_lock.c:1476
[Sun Mar 16 11:39:44 2008]0xc09de194 CPU 0 
/rest/work/woods/m-NetBSD-4/sys/kern/kern_synch.c:497
[Sun Mar 16 11:39:44 2008]0xc5e9ce78 CPU 0 
/rest/work/woods/m-NetBSD-4/sys/kern/kern_event.c:1259
[Sun Mar 16 11:39:44 2008]0x80000000
[Sun Mar 16 11:39:44 2008]db{0}> reboot
[Sun Mar 16 11:40:15 2008]syncing disks... 
[Sun Mar 16 11:40:15 2008]simple_lock: locking against myself
[Sun Mar 16 11:40:15 2008]lock: 0xc09de194, currently at: 
/rest/work/woods/m-NetBSD-4/sys/kern/kern_synch.c:1237
[Sun Mar 16 11:40:15 2008]on CPU 0
[Sun Mar 16 11:40:15 2008]last locked: 
/rest/work/woods/m-NetBSD-4/sys/kern/kern_synch.c:497
[Sun Mar 16 11:40:15 2008]last unlocked: 
/rest/work/woods/m-NetBSD-4/sys/kern/kern_sa.c:1466
[Sun Mar 16 11:40:15 2008]kernel: supervisor trap page fault, code=0
[Sun Mar 16 11:40:15 2008]Stopped in pid 2073.2 (apcupsd) at      
netbsd:db_read_bytes+0x30:      movl    0(%esi),%eax
[Sun Mar 16 11:40:15 2008]db{0}> reboot
[Sun Mar 16 11:40:23 2008]rebooting...


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>Fix: