Re: zfs: Fatal trap 12: page fault while in kernel mode

On Jul 29, 2009, at 19:18, Andriy Gapon wrote:

>
> Thanks a lot again!
>
> Could you please try the following change?
> In sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c, in  
> function
> zfs_inactive() insert the following line:
> 	vrecycle(vp, curthread);
> before the following line:
> 	zfs_znode_free(zp);
>
> This is in "if (zp->z_dbuf == NULL)" branch.
>
> I hope that this should work in concert with the patch that Pawel  
> has posted.
>
> P.S.
> Also Pawel has told me that adding 'CFLAGS+=-DDEBUG=1' to sys/ 
> modules/zfs/Makefile
> should enable additional debugging checks (ASSERTs) in ZFS code.
>
> -- 
> Andriy Gapon
Better backtraces:

Without your vrecycle() addition, and with the -DDEBUG=1 one (note to  
self: core.txt.32):

Unread portion of the kernel message buffer:
panic: solaris assert: ((zp)->z_vnode) == ((void *)0), file: /usr/src/ 
sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/ 
zfs_znode.c, line: 1043
cpuid = 0
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2a
panic() at panic+0x182
zfs_znode_free() at zfs_znode_free+0xef
zfs_freebsd_inactive() at zfs_freebsd_inactive+0x1a
VOP_INACTIVE_APV() at VOP_INACTIVE_APV+0x4a
vinactive() at vinactive+0x6a
vput() at vput+0x1c6
dounmount() at dounmount+0x4af
unmount() at unmount+0x3c8
syscall() at syscall+0x28f
Xfast_syscall() at Xfast_syscall+0xe1
--- syscall (22, FreeBSD ELF64, unmount), rip = 0x80104e9ec, rsp =  
0x7fffffffaa98, rbp = 0x801223300 ---
KDB: enter: panic
panic: from debugger
cpuid = 0
Uptime: 1m5s
Physical memory: 2034 MB
Dumping 1405 MB: ...

#11 0xffffffff8033a9cb in panic (fmt=Variable "fmt" is not available.
)
     at /usr/src/sys/kern/kern_shutdown.c:558
#12 0xffffffff80aed21f in zfs_znode_free () from /boot/kernel/zfs.ko
#13 0xffffffff80b10a9a in zfs_freebsd_inactive () from /boot/kernel/ 
zfs.ko
#14 0xffffffff805c5b5a in VOP_INACTIVE_APV (vop=0xffffffff80b88220,
     a=0xffffff00401b9a48) at vnode_if.c:1863
#15 0xffffffff803c6aaa in vinactive (vp=0xffffff004038c3b0,
     td=0xffffff0040031000) at vnode_if.h:807
#16 0xffffffff803cbf26 in vput (vp=0xffffff004038c3b0)
     at /usr/src/sys/kern/vfs_subr.c:2257
#17 0xffffffff803c57ef in dounmount (mp=0xffffff0001cea8d0, flags=0,  
td=Variable "td" is not available.
)
     at /usr/src/sys/kern/vfs_mount.c:1333
#18 0xffffffff803c5df8 in unmount (td=0xffffff0013adfab0,
     uap=0xffffff803ead0bf0) at /usr/src/sys/kern/vfs_mount.c:1174
#19 0xffffffff805980bf in syscall (frame=0xffffff803ead0c80)
     at /usr/src/sys/amd64/amd64/trap.c:984
#20 0xffffffff8057e2c1 in Xfast_syscall ()    at /usr/src/sys/amd64/ 
amd64/exception.S:373
#21 0x000000080104e9ec in ?? ()
Previous frame inner to this frame (corrupt stack?)

---------------------------

WITH the vrecycle() and -DDEBUG=1:

kernel trap 9 with interrupts disabled


Fatal trap 9: general protection fault while in kernel mode
cpuid = 0; apic id = 00
instruction pointer     = 0x20:0xffffffff80342b99
stack pointer           = 0x28:0xffffff803eaf8910
frame pointer           = 0x28:0xffffff803eaf8970
code segment            = base 0x0, limit 0xfffff, type 0x1b
                         = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = resume, IOPL = 0
current process         = 1414 (zpool)
panic: from debugger
cpuid = 0
KDB: stack backtrace:
Uptime: 1m16s
Physical memory: 2034 MB
Dumping 1407 MB: ...

#9  0xffffffff805986aa in trap (frame=0xffffff803eaf8860) at /usr/src/ 
sys/amd64/amd64/trap.c:639
#10 0xffffffff8057dfe7 in calltrap () at /usr/src/sys/amd64/amd64/ 
exception.S:224
#11 0xffffffff80342b99 in _sx_xlock_hard (sx=0xffffff0044136251,  
tid=18446742975340199936, opts=Variable "opts" is not available.
)
     at /usr/src/sys/kern/kern_sx.c:575
#12 0xffffffff8034350e in _sx_xlock (sx=Variable "sx" is not available.
) at sx.h:155
#13 0xffffffff80aed172 in zfs_znode_free () from /boot/kernel/zfs.ko
#14 0xffffffff80b10a8a in zfs_freebsd_inactive () from /boot/kernel/ 
zfs.ko
#15 0xffffffff805c5b5a in VOP_INACTIVE_APV (vop=0xffffff0044136251,  
a=0xffffff0015b9cd38) at vnode_if.c:1863
#16 0xffffffff803c6aaa in vinactive (vp=0xffffff00443dc588,  
td=0xffffff0044136001) at vnode_if.h:807
#17 0xffffffff803cbf26 in vput (vp=0xffffff00443dc588) at /usr/src/sys/ 
kern/vfs_subr.c:2257
#18 0xffffffff803c57ef in dounmount (mp=0xffffff0001cc38d0, flags=0,  
td=Variable "td" is not available.
) at /usr/src/sys/kern/vfs_mount.c:1333
#19 0xffffffff803c5df8 in unmount (td=0xffffff004415c000,  
uap=0xffffff803eaf8bf0)
     at /usr/src/sys/kern/vfs_mount.c:1174
#20 0xffffffff805980bf in syscall (frame=0xffffff803eaf8c80) at /usr/ 
src/sys/amd64/amd64/trap.c:984
#21 0xffffffff8057e2c1 in Xfast_syscall () at /usr/src/sys/amd64/amd64/ 
exception.S:373
#22 0x000000080104e9ec in ?? ()
Previous frame inner to this frame (corrupt stack?)

Time to sleep. I only have the kernel.debug for the latter panic, by  
the way, but at a quick glance they appear to be the same except for  
the panic line...?

Regards,
Thomas