Successfully grabbed the panic in developer:
Kernel page fault with the following non-sleepable locks held:
exclusive sleep mutex em0 (EM TX Lock) r = 0 (0xc2f52580) locked @ /usr/pfSensesrc/src/sys/dev/e1000/if_lem.c:1350
KDB: stack backtrace:
X_db_sym_numargs(c0eb7066,e302aa90,c0a41d45,546,0,...) at X_db_sym_numargs+0x146
kdb_backtrace(546,0,ffffffff,c145d1ac,e302aac8,...) at kdb_backtrace+0x29
witness_display_spinlock(c0eb957e,e302aadc,4,1,0,...) at witness_display_spinlock+0x75
witness_warn(5,0,c0ef792d,14,c131b140,...) at witness_warn+0x20d
trap(e302ab68) at trap+0x19e
alltraps(c336dc00,dedeadc0,c336dc00,c336dc00,e302abf0,...) at alltraps+0x1b
m_tag_delete_chain(c336dc00,0,c0e6e512,0,c2ed9bc0,...) at m_tag_delete_chain+0x3f
reallocf(c336dc00,100,0,c0a42798,df,...) at reallocf+0x8a5
uma_zfree_arg(c1d7e380,c336dc00,0,bc,e302ac84,...) at uma_zfree_arg+0x29
m_freem(c336dc00,4,c0e6e512,b87,c2f4e000,...) at m_freem+0x43
ed_probe_RTL80x9(c2f52580,0,c0e6e512,546,c2f525bc,...) at 0xc06ec448
ed_probe_RTL80x9(c2f4e000,1,c0eb8937,4f,c2edb918,...) at 0xc06efe10
taskqueue_run(c2edb900,c2edb918,c0ea5cf0,0,c0eb1f96,...) at taskqueue_run+0x103
taskqueue_thread_loop(c2f525ec,e302ad38,c0eaeb05,344,c131b140,...) at taskqueue_thread_loop+0x68
fork_exit(c0a3afc0,c2f525ec,e302ad38) at fork_exit+0xb8
fork_trampoline() at fork_trampoline+0x8
--- trap 0, eip = 0, esp = 0xe302ad70, ebp = 0 ---
Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address= 0xdedeadc0
fault code= supervisor read, page not present
instruction pointer= 0x20:0xc0a60fe8
stack pointer = 0x28:0xe302aba8
frame pointer = 0x28:0xe302abb8
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= 0 (em0 taskq)
[thread pid 0 tid 64050 ]
Stopped at m_tag_delete+0x48: movl 0(%ecx),%eax
db>