ZFS hang in zfs_freebsd_rename

[Steven Hartland]

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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