FYI: a note about some automatic attach/detach stuff

[mjacob at freebsd.org]

Barf. This happened after an event caused a rescan.. Sigh... Hopefully 
I'll get this tracked down for RELENG_7.0

proberegister: Unable to probe new device. Unable to allocate softc
(xpt0:isp0:0:395:0): xpt_scan_lun: cam_alloc_periph returned an error, 
can't continue probe
Kernel page fault with the following non-sleepable locks held:
exclusive sleep mutex isp r = 0 (0xc2d71090) locked @ cam/cam_xpt.c:7140
KDB: stack backtrace:
db_trace_self_wrapper(c0a3b900,d3c83ae4,c077bebd,c0a3bcbf,d3c83af8,...) 
at db_trace_self_wrapper+0x26
kdb_backtrace(c0a3bcbf,d3c83af8,4,1,0,...) at kdb_backtrace+0x29
witness_warn(5,0,c0a63882,c073a77c,c2e66000,...) at witness_warn+0x1cd
trap(d3c83b80) at trap+0x115
calltrap() at calltrap+0x6
--- trap 0xc, eip = 0xc0468ef4, esp = 0xd3c83bc0, ebp = 0xd3c83c04 ---
xpt_scan_bus(c2dc4680,c4e4d800,d3c83c20,246,c2ead594,...) at 
xpt_scan_bus+0x334
camisr_runqueue(c2d71090,0,c09efaf9,1be4,0,...) at camisr_runqueue+0x39f
camisr(0,0,c0a35bf3,471,c2dc4664,...) at camisr+0x11a
ithread_loop(c2e5a0e0,d3c83d38,7c72604,3e800001,c2e66000,...) at 
ithread_loop+0x1b5
fork_exit(c072afc0,c2e5a0e0,d3c83d38) at fork_exit+0x57
fork_trampoline() at fork_trampoline+0x8
--- trap 0, eip = 0, esp = 0xd3c83d70, ebp = 0 ---


Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 01
fault virtual address   = 0xdeadc141
fault code              = supervisor read, page not present
instruction pointer     = 0x20:0xc0468ef4
stack pointer           = 0x28:0xd3c83bc0
frame pointer           = 0x28:0xd3c83c04
code segment            = base 0x0, limit 0xfffff, type 0x1b
                         = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 19 (swi2: cambio)
[thread pid 19 tid 100015 ]
Stopped at      xpt_scan_bus+0x334:     testb   $0x4,0x63(%edx)
db> bt
Tracing pid 19 tid 100015 td 0xc2d84800
xpt_scan_bus(c2dc4680,c4e4d800,d3c83c20,246,c2ead594,...) at 
xpt_scan_bus+0x334
camisr_runqueue(c2d71090,0,c09efaf9,1be4,0,...) at camisr_runqueue+0x39f
camisr(0,0,c0a35bf3,471,c2dc4664,...) at camisr+0x11a
ithread_loop(c2e5a0e0,d3c83d38,7c72604,3e800001,c2e66000,...) at 
ithread_loop+0x1b5
fork_exit(c072afc0,c2e5a0e0,d3c83d38) at fork_exit+0x57
fork_trampoline() at fork_trampoline+0x8
--- trap 0, eip = 0, esp = 0xd3c83d70, ebp = 0 ---
db>