Re: FreeBSD 12.3/13.1 NFS client hang

Kurt Jaeger <pi@freebsd.org> wrote:
> > > I'm having issues with the NFS clients on FreeBSD 12.3 and 13.1
>
> I have it with an 13.0p7 client against an 13.1 server with
> a hanging soft-mount (I tried unmount to change it to a hard mount).
> 
> 61585  93- D+        0:00.00 umount /office/serv
> 61635 133  D         0:00.00 umount -f /office/serv
> 7784 138  D         0:00.00 umount -N /office/serv
The first umount must be "-N". Once you've hung a non "-N" umount,
rebooting is the only option.
(I have thought of doing a "umount -N -A" (for all NFS mounts), which
would allow it to kill off all NFS activity without even finding the pathname
for the mountpoint, but I have not done so.)

> and procstat:
>
> # procstat -kk 7784
>  PID    TID COMM                TDNAME              KSTACK
> 7784 107226 umount              -                   mi_switch+0xc1 sleeplk+0xec lockmgr_xlock_hard+0x345 _vn_lock+0x48 vget_finish+0x21 cache_lookup+0x299 vfs_cache_lookup+0x7b lookup+0x68c namei+0x487 kern_unmount+0x164 amd64_syscall+0x10c fast_syscall_common+0xf8
> # procstat -kk 61635
>  PID    TID COMM                TDNAME              KSTACK
> 61635 775458 umount              -                   mi_switch+0xc1 sleeplk+0xec lockmgr_slock_hard+0x382 _vn_lock+0x48 vget_finish+0x21 cache_lookup+0x299 vfs_cache_lookup+0x7b lookup+0x68c namei+0x487 sys_statfs+0xc3 amd64_syscall+0x10c fast_syscall_common+0xf8
> # procstat -kk 61585
>  PID    TID COMM                TDNAME              KSTACK
> 61585 516164 umount              -                   mi_switch+0xc1 sleeplk+0xec lockmgr_xlock_hard+0x345 nfs_lock+0x2c vop_sigdefer+0x2b _vn_lock+0x48 vflush+0x151 nfs_unmount+0xc3 vfs_unmount_sigdefer+0x2e dounmount+0x437 kern_unmount+0x332 amd64_syscall+0x10c fast_syscall_common+0xf8
These just show that they are waiting for NFS vnodes. In the "ps" there are
threads waiting on zfs vnodes as well.

> ps-axHl can be found at
> 
> https://people.freebsd.org/~pi/logs/ps-axHl.txt
I suspect your problem might be related to wired pages. Note that
several threads are sleeping on "vmopar". I'm no vm guy, but I
think that might mean too many pages have become wired.

rick

> > systems hanging when using a CentOS 7 server.
> First, make sure you are using hard mounts. "soft" or "intr" mounts won't
> work and will mess up the session sooner or later. (A messed up session could
> result in no free slots on the session and that will wedge threads in
> nfsv4_sequencelookup() as you describe.
> (This is briefly described in the BUGS section of "man mount_nfs".)
>
> Do a:
> # nfsstat -m
> on the clients and look for "hard".

No output at all for that 8-(

--
pi@FreeBSD.org         +49 171 3101372                  Now what ?