panic on removing urtw0

[Eitan Adler]

I recently encountered a kernel panic upon removing a urtw0 device.
This removal occurred during machine shutdown.

The crashing kernel and textdump is available upon request.

Unread portion of the kernel message buffer:
urtw0: failed to stop (USB_ERR_NOT_CONFIGURED)


Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 01
fault virtual address   = 0x368
fault code              = supervisor read data, page not present
instruction pointer     = 0x20:0xffffffff808c4be7
stack pointer           = 0x28:0xffffff8227152730
frame pointer           = 0x28:0xffffff8227152780
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 15 (usbus2)
trap number             = 12
panic: page fault
cpuid = 1

KDB: stack backtrace:
#0 0xffffffff8090c7a6 at kdb_backtrace+0x66
#1 0xffffffff808d67be at panic+0x1ce
#2 0xffffffff80bc4140 at trap_fatal+0x290
#3 0xffffffff80bc447d at trap_pfault+0x1ed
#4 0xffffffff80bc4a9e at trap+0x3ce
#5 0xffffffff80baf05f at calltrap+0x8
#6 0xffffffff809a541a at ieee80211_ageq_remove+0xea
#7 0xffffffff809a54c9 at ieee80211_ageq_drain_node+0x9
#8 0xffffffff809c584a at node_cleanup+0x6a
#9 0xffffffff809c5960 at node_free+0x30
#10 0xffffffff8077f97b at urtw_free_data_list+0x4b
#11 0xffffffff80785a45 at urtw_detach+0xd5
#12 0xffffffff80905a84 at device_detach+0x74
#13 0xffffffff80750388 at usb_detach_device+0x58
#14 0xffffffff80750524 at usb_unconfigure+0x34
#15 0xffffffff807507c5 at usb_free_device+0x195
#16 0xffffffff80758dce at uhub_explore+0x1be
#17 0xffffffff807590d4 at uhub_explore+0x4c4


-- 
Eitan Adler