Subject: Panic in simple_lock_switchcheck
To: None <>
From: Sverre Froyen <>
List: current-users
Date: 05/21/2007 15:38:29

It looks like a new locking issue has been introduced some time after 22 
March.   I use bogofilter to detect spam and with recent kernels I get panics 
when marking emails as spam or ham (running bogofilter -s and bogofilter -n).  
After reboot, the bogofilter database is always corrupted.  The database 
resides on an LFS file system.

Here's a backtrace from the core dump:

#9  0xc03b03fb in simple_lock_switchcheck ()
    at /usr/src/sys/kern/kern_lock.c:1402
#10 0xc03c118a in mi_switch (l=0xcd0c2a60)
    at /usr/src/sys/kern/kern_synch.c:363
#11 0xc03bf13a in sleepq_block (timo=0, catch=false)
    at /usr/src/sys/kern/kern_sleepq.c:273
#12 0xc03c1f41 in ltsleep (ident=0xccb5bfa4, priority=17,
    wmesg=0xc0727475 "seg_iocount", timo=0, interlock=0xc1742f54)
    at /usr/src/sys/kern/kern_synch.c:180
#13 0xc0341604 in lfs_segunlock (fs=0xc1742800)
    at /usr/src/sys/ufs/lfs/lfs_subr.c:532
#14 0xc034e8b1 in lfs_putpages (v=0xcd8dfb30)
    at /usr/src/sys/ufs/lfs/lfs_vnops.c:2294
#15 0xc0413080 in VOP_PUTPAGES (vp=0xcd9cceb8, offlo=0, offhi=0, flags=3)
    at /usr/src/sys/kern/vnode_if.c:1592
#16 0xc034c4af in lfs_fsync (v=0xcd8dfbb8)
    at /usr/src/sys/ufs/lfs/lfs_vnops.c:323
#17 0xc0412b29 in VOP_FSYNC (vp=0xcd9cceb8, cred=0xccfd8aa8, flags=3, offlo=0,
    offhi=0, l=0xcd0c2a60) at /usr/src/sys/kern/vnode_if.c:724
#18 0xc0409365 in sys_fdatasync (l=0xcd0c2a60, v=0xcd8dfc48, 
    at /usr/src/sys/kern/vfs_syscalls.c:3218
#19 0xc0470ce6 in syscall_plain (frame=0xcd8dfc88)
    at /usr/src/sys/arch/i386/i386/syscall.c:148
#20 0xc01004b7 in syscall1 ()

The system is current i386 from yesterday plus today's ihashlocking patch from 
Blair Sadewitz.

Is this a known issue?  What other information should I extract (I believe I 
can trigger this panic easily)?