panic: sx_xlock() of destroyed sx @ /zoo/kris/src8/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_rlock.c:535

[Pawel Jakub Dawidek]

On Fri, Sep 11, 2009 at 07:05:59PM +0100, Kris Kennaway wrote:
> Kris Kennaway wrote:
> >9.0 doing I/O to a zfs:
> >
> >panic: sx_xlock() of destroyed sx @ 
> >/zoo/kris/src8/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_rlock.c:535 
> >
> >db> wh
> >Tracing pid 14 tid 100047 td 0xffffff000357c720
> >kdb_enter() at kdb_enter+0x3d
> >panic() at panic+0x17b
> >_sx_xlock() at _sx_xlock+0xe9
> >zfs_range_unlock() at zfs_range_unlock+0x38
> >zfs_get_data() at zfs_get_data+0xd7
> >zil_commit() at zil_commit+0x532
> >zfs_sync() at zfs_sync+0xa6
> >sync_fsync() at sync_fsync+0x13a
> >VOP_FSYNC_APV() at VOP_FSYNC_APV+0xb7
> >sync_vnode() at sync_vnode+0x157
> >sched_sync() at sched_sync+0x1d1
> >fork_exit() at fork_exit+0x12a
> >fork_trampoline() at fork_trampoline+0xe
> >--- trap 0, rip = 0, rsp = 0xffffff8125da0d30, rbp = 0 ---
> >
> >This was essentially just doing make world + cvs update + tar creation 
> >in a loop and failed after about a week.
> 
> Any ideas?  Machine is still in DDB.

I was trying to reproduce it by doing much more frequent syncs and
lowering vnodes limit, so they are inactivated more often, but I wasn't
able to reproduce it.

The problem here is that we lock a range for the given znode, but before
we unlock the range, znode is destroyed.

If you compile ZFS with debug (you have to uncomment CFLAGS+=-DDEBUG=1
in sys/modules/zfs/Makefile and recompile), we should be able to catch
who is killing the znode, because then, avl_destroy(&zp->z_range_avl)
should trigger a panic that tree isn't empty.

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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