ZFS hang in zfs_freebsd_rename

[Steven Hartland]

There have been quite a few reported issues with this some at least have 
been fix, but as with anything the only way to be sure is to test it.

On 15/12/2015 14:52, Bengt Ahlgren wrote:
> Yes, that is on the todo list...
>
> So this is likely fixed then in 10.x?
>
> Bengt
>
> Steven Hartland <killing at multiplay.co.uk> writes:
>
>> Not a surprise in 9.x unfortunately, try upgrading to 10.x
>>
>> On 15/12/2015 12:51, Bengt Ahlgren wrote:
>>> We have a server running 9.3-REL which currenly has two quite large zfs
>>> pools:
>>>
>>> NAME   SIZE  ALLOC   FREE    CAP  DEDUP  HEALTH  ALTROOT
>>> p1    18.1T  10.7T  7.38T    59%  1.00x  ONLINE  -
>>> p2    43.5T  29.1T  14.4T    66%  1.00x  ONLINE  -
>>>
>>> It has been running without any issues for some time now.  Once, just
>>> now, processes are getting stuck and impossible to kill on accessing a
>>> particular directory in the p2 pool.  That pool is a 2x6 disk raidz2.
>>>
>>> One process is stuck in zfs_freebsd_rename, and other processes
>>> accessing that particular directory also get stuck.  The system is now
>>> almost completely idle.
>>>
>>> Output from kgdb on the running system for that first process:
>>>
>>> Thread 651 (Thread 102157):
>>> #0  sched_switch (td=0xfffffe0b14059920, newtd=0xfffffe001633e920, flags=<value optimized out>)
>>>       at /usr/src/sys/kern/sched_ule.c:1904
>>> #1  0xffffffff808f4604 in mi_switch (flags=260, newtd=0x0) at /usr/src/sys/kern/kern_synch.c:485
>>> #2 0xffffffff809308e2 in sleepq_wait (wchan=0xfffffe0135b60488,
>>> pri=96) at /usr/src/sys/kern/subr_sleepqueue.c:618
>>> #3  0xffffffff808cf922 in __lockmgr_args (lk=0xfffffe0135b60488, flags=524544, ilk=0xfffffe0135b604b8,
>>>       wmesg=<value optimized out>, pri=<value optimized out>, timo=<value optimized out>,
>>>       file=0xffffffff80f0d782 "/usr/src/sys/kern/vfs_subr.c", line=2337) at /usr/src/sys/kern/kern_lock.c:221
>>> #4  0xffffffff80977369 in vop_stdlock (ap=<value optimized out>) at lockmgr.h:97
>>> #5  0xffffffff80dd4a04 in VOP_LOCK1_APV (vop=0xffffffff813e8160, a=0xffffffa07f935520) at vnode_if.c:2052
>>> #6  0xffffffff80998c17 in _vn_lock (vp=0xfffffe0135b603f0, flags=524288,
>>>       file=0xffffffff80f0d782 "/usr/src/sys/kern/vfs_subr.c", line=2337) at vnode_if.h:859
>>> #7  0xffffffff8098b621 in vputx (vp=0xfffffe0135b603f0, func=1) at /usr/src/sys/kern/vfs_subr.c:2337
>>> #8  0xffffffff81ac7955 in zfs_rename_unlock (zlpp=0xffffffa07f9356b8)
>>>       at /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c:3609
>>> #9  0xffffffff81ac8c72 in zfs_freebsd_rename (ap=<value optimized out>)
>>>       at /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c:4039
>>> #10 0xffffffff80dd4f04 in VOP_RENAME_APV (vop=0xffffffff81b47d40, a=0xffffffa07f9358e0) at vnode_if.c:1522
>>> #11 0xffffffff80996bbd in kern_renameat (td=<value optimized out>, oldfd=<value optimized out>,
>>>       old=<value optimized out>, newfd=-100, new=0x1826a9af00 <Error reading address 0x1826a9af00: Bad address>,
>>>       pathseg=<value optimized out>) at vnode_if.h:636
>>> #12 0xffffffff80cd228a in amd64_syscall (td=0xfffffe0b14059920, traced=0) at subr_syscall.c:135
>>> #13 0xffffffff80cbc907 in Xfast_syscall () at /usr/src/sys/amd64/amd64/exception.S:396
>>> ---Type <return> to continue, or q <return> to quit---
>>> #14 0x0000000800cc1acc in ?? ()
>>> Previous frame inner to this frame (corrupt stack?)
>>>
>>> Full procstat -kk -a and kgdb "thread apply all bt" can be found here:
>>>
>>> https://www.sics.se/~bengta/ZFS-hang/
>>>
>>> I don't know how to produce "alltrace in ddb" as the instructions in the
>>> wiki says.  It runs the GENERIC kernel, so perhaps it isn't possible?
>>>
>>> I checked "camcontrol tags" for all the disks in the pool - all have
>>> zeroes for dev_active, devq_queued and held.
>>>
>>> Is there anything else I can check while the machine is up?  I however
>>> need to restart it pretty soon.
>>>
>>> Bengt
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