Bug 201118

See the stack trace; the details of what happened -- on demand.

All the software built, in a regular manner, from the source:

---------------------------
10.1-STABLE #0 r283831: Sun May 31 13:52:02 EDT 2015
---------------------------

Fatal trap 1: privileged instruction fault while in kernel mode
cpuid = 0; apic id = 10
instruction pointer     = 0x20:0xffffffff8098fa01
stack pointer           = 0x28:0xfffffe0113d1b550
frame pointer           = 0x28:0xfffffe0113d1b5a0
code segment            = base rx0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 2063 (mplayer)
trap number             = 1
panic: privileged instruction fault
cpuid = 0
KDB: stack backtrace:
#0 0xffffffff8097cfe0 at kdb_backtrace+0x60
#1 0xffffffff80940869 at vpanic+0x189
#2 0xffffffff809406d3 at panic+0x43
#3 0xffffffff80d3400f at trap_fatal+0x38f
#4 0xffffffff80d33c6c at trap+0x75c
#5 0xffffffff80d196a2 at calltrap+0x8
#6 0xffffffff81accb70 at dmu_read_uio_dnode+0xa0
#7 0xffffffff81accaa4 at dmu_read_uio_dbuf+0x34
#8 0xffffffff81b639a3 at zfs_freebsd_read+0x3e3
#9 0xffffffff80e5adb1 at VOP_READ_APV+0xa1
#10 0xffffffff809f3975 at vn_read+0x165
#11 0xffffffff809eff1b at vn_io_fault+0x10b
#12 0xffffffff809944d5 at dofileread+0x95
#13 0xffffffff809941f8 at kern_readv+0x68
#14 0xffffffff80994183 at sys_read+0x63
#15 0xffffffff80d34927 at amd64_syscall+0x357
#16 0xffffffff80d1998b at Xfast_syscall+0xfb
Uptime: 3h39m2s

#0  doadump (textdump=<value optimized out>) at pcpu.h:219
219             __asm("movq %%gs:%1,%0" : "=r" (td)

(kgdb) bt
#0  doadump (textdump=<value optimized out>) at pcpu.h:219
#1  0xffffffff80940462 in kern_reboot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:451
#2  0xffffffff809408a8 in vpanic (fmt=<value optimized out>, ap=<value optimized out>)
    at /usr/src/sys/kern/kern_shutdown.c:758
#3  0xffffffff809406d3 in panic (fmt=0x0) at /usr/src/sys/kern/kern_shutdown.c:687
#4  0xffffffff80d3400f in trap_fatal (frame=<value optimized out>, eva=<value optimized out>)
    at /usr/src/sys/amd64/amd64/trap.c:857
#5  0xffffffff80d33c6c in trap (frame=<value optimized out>) at /usr/src/sys/amd64/amd64/trap.c:203
#6  0xffffffff80d196a2 in calltrap () at /usr/src/sys/amd64/amd64/exception.S:236
#7  0xffffffff8098fa01 in uiomove_faultflag (cp=0xfffff80019005600, n=319, uio=0xfffffe0113d1b8e0, 
    nofault=<value optimized out>) at proc.h:983
#8  0xffffffff81accb70 in dmu_read_uio_dnode () from /boot/kernel/zfs.ko
#9  0xffffffff81accaa4 in dmu_read_uio_dbuf () from /boot/kernel/zfs.ko
#10 0xffffffff81b639a3 in zfs_freebsd_read () from /boot/kernel/zfs.ko
#11 0xffffffff80e5adb1 in VOP_READ_APV (vop=<value optimized out>, a=<value optimized out>) at vnode_if.c:932
#12 0xffffffff809f3975 in vn_read (fp=0xfffff8001915e910, uio=0xfffffe0113d1b8e0, active_cred=<value optimized out>, 
    flags=<value optimized out>, td=0x2d) at vnode_if.h:384
#13 0xffffffff809eff1b in vn_io_fault (fp=0xfffff8001915e910, uio=0xfffffe0113d1b8e0, active_cred=0xfffffe0113d1b8e0, 
    flags=0, td=0x2d) at /usr/src/sys/kern/vfs_vnops.c:1159
#14 0xffffffff809944d5 in dofileread (td=0xfffff8001748f490, fd=5, fp=0xfffff8001915e910, auio=0xfffffe0113d1b8e0, 
    offset=<value optimized out>, flags=0) at file.h:296
#15 0xffffffff809941f8 in kern_readv (td=0xfffff8001748f490, fd=5, auio=0xfffffe0113d1b8e0)
    at /usr/src/sys/kern/sys_generic.c:270
#16 0xffffffff80994183 in sys_read (td=<value optimized out>, uap=<value optimized out>)
    at /usr/src/sys/kern/sys_generic.c:185
#17 0xffffffff80d34927 in amd64_syscall (td=0xfffff8001748f490, traced=0) at subr_syscall.c:134
#18 0xffffffff80d1998b in Xfast_syscall () at /usr/src/sys/amd64/amd64/exception.S:396
#19 0x00000008074abe8a in ?? ()
Previous frame inner to this frame (corrupt stack?)
Cu