panic on zfs unmount

[Stefan Bethke]

I still sometimes get the "lost" .zfs/snapshot directory, with resulting panic, and it just happened again.  I have the full crash dump, if anyone wants to look at details.

# cd /jail/foo/.zfs
# ls
ls: snapshot: Bad file descriptor
# cd
# zfs umount tank/jail/foo
Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address	= 0xa8
fault code		= supervisor write data, page not present
instruction pointer	= 0x20:0xffffffff8033fac5
stack pointer	        = 0x28:0xffffff80626cf9d0
frame pointer	        = 0x28:0xffffff80626cf9e0
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		= 38362 (zfs)
trap number		= 12
panic: page fault
cpuid = 0
Uptime: 7d3h33m46s
Physical memory: 3313 MB

#0  doadump () at pcpu.h:223
223	pcpu.h: No such file or directory.
	in pcpu.h
(kgdb) #0  doadump () at pcpu.h:223
#1  0xffffffff80337bd9 in boot (howto=260)
    at /usr/src/sys/kern/kern_shutdown.c:416
#2  0xffffffff8033802c in panic (fmt=Variable "fmt" is not available.
)
    at /usr/src/sys/kern/kern_shutdown.c:579
#3  0xffffffff805cc2ad in trap_fatal (frame=0xc, eva=Variable "eva" is not available.
)
    at /usr/src/sys/amd64/amd64/trap.c:857
#4  0xffffffff805cc694 in trap_pfault (frame=0xffffff80626cf920, usermode=0)
    at /usr/src/sys/amd64/amd64/trap.c:773
#5  0xffffffff805cd06a in trap (frame=0xffffff80626cf920)
    at /usr/src/sys/amd64/amd64/trap.c:499
#6  0xffffffff805b2943 in calltrap ()
    at /usr/src/sys/amd64/amd64/exception.S:224
#7  0xffffffff8033fac5 in _sx_xlock (sx=0x90, opts=0, 
    file=0xffffffff80ac1d30 "/usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c", line=1349) at atomic.h:158
#8  0xffffffff80a53b85 in zfsctl_umount_snapshots (vfsp=Variable "vfsp" is not available.
)
    at /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c:1349
#9  0xffffffff80a604f9 in zfs_umount (vfsp=0xffffff00017518d0, fflag=0)
    at /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c:1020
#10 0xffffffff803c080a in dounmount (mp=0xffffff00017518d0, flags=0, td=Variable "td" is not available.
)
    at /usr/src/sys/kern/vfs_mount.c:1294
#11 0xffffffff803c1038 in unmount (td=0xffffff002ed50720, 
    uap=0xffffff80626cfbf0) at /usr/src/sys/kern/vfs_mount.c:1179
#12 0xffffffff805cc906 in syscall (frame=0xffffff80626cfc80)
    at /usr/src/sys/amd64/amd64/trap.c:989
#13 0xffffffff805b2c21 in Xfast_syscall ()
    at /usr/src/sys/amd64/amd64/exception.S:373
#14 0x0000000800f4ba4c in ?? ()
Previous frame inner to this frame (corrupt stack?)
(kgdb) 

-- 
Stefan Bethke <stb at lassitu.de>   Fon +49 151 14070811