another zfs panic

[Pawel Jakub Dawidek]

On Thu, Jul 30, 2009 at 05:38:57AM +0400, Maxim Dounin wrote:
> Hello!
> 
> Here is zfs panic I'm able to reproduce by running an scp from 
> remote machine to zfs volume and 3 parallel untars of ports tree 
> in cycle.  Not sure that everything is required, but the above 
> workload triggers panic in several hours.
> 
> This is on fresh current with GENERIC kernel:
> 
> panic: sx_xlock() of destroyed sx @ 
> /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_rlock.c:535
> cpuid = 6
> KDB: enter: panic
> [thread pid 36 tid 100071 ]
> Stopped at      kdb_enter+0x3d: movq    $0,0x68a040(%rip)
> db> bt
> Tracing pid 36 tid 100071 td 0xffffff00040f3720
> kdb_enter() at kdb_enter+0x3d
> panic() at panic+0x17b
> _sx_xlock() at _sx_xlock+0xfc
> zfs_range_unlock() at zfs_range_unlock+0x38
> zfs_get_data() at zfs_get_data+0xc1
> zil_commit() at zil_commit+0x532
> zfs_sync() at zfs_sync+0xa6
> sync_fsync() at sync_fsync+0x13a
> 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 = 0xffffff80e7ee3d30, rbp = 0 ---
> 
> Machine is otherwise idle.  The only zfs-related tuning applied is 
> compression=gzip-9.
> 
> Please let me know if you want me to test some patches.

The kernel syncer tries to sync vnode which has its znode already
destroyed. There is one place (that we know of) where vrecycle() is
missing. Could you try this patch:

	http://people.freebsd.org/~pjd/patches/zfs_vnops.c.2.patch

-- 
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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