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Date:      Fri, 31 May 2024 15:39:01 -0400
From:      J David <j.david.lists@gmail.com>
To:        FreeBSD FS <freebsd-fs@freebsd.org>
Subject:   NFSv4 hangs on 13.3
Message-ID:  <CABXB=RTH6s25EMQzDbg8WPr1hKtjKOJGVh3no0TFcNC=ufwXCw@mail.gmail.com>

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In an attempt to narrow down the problems we have with NFS v4.2, we've
set up a FreeBSD 13.3 server that mirrors some read-only data from our
Linux NFS servers.

We are still observing occasional hangs on the FreeBSD 13.3 client machines=
.

When these hangs occur, anything that touches the mountpoint
(including "umount -N") hangs indefinitely. There is nothing in dmesg.

The only even slightly informative data I could gather is an "ls
/mount/point" kstack:

$ sudo procstat -kk 94676
  PID    TID COMM                TDNAME              KSTACK
94676 976876 ls                  -                   mi_switch+0xbf
sleeplk+0xea lockmgr_slock_hard+0x3a5 nfs_lock+0x29 vop_sigdefer+0x2a
_vn_lock+0x47 vfs_cache_root+0x9d vfs_root_sigdefer+0x35 lookup+0x88a
namei+0x24a kern_statat+0xf8 sys_fstatat+0x27 amd64_syscall+0x110
fast_syscall_common+0xf8

During this time, the NFS server continues serving other clients, and
the affected client can access other NFS servers without hanging.

The "nfsstat -m" for this mountpoint looks like this:

nfsv4,minorversion=3D2,oneopenown,tcp,resvport,nconnect=3D1,hard,cto,nolock=
d,sec=3Dsys,acdirmin=3D3,acdirmax=3D60,acregmin=3D5,acregmax=3D60,nametimeo=
=3D60,negnametimeo=3D60,rsize=3D65536,wsize=3D65536,readdirsize=3D65536,rea=
dahead=3D1,wcommitsize=3D16777216,timeout=3D120,retrans=3D2147483647

with these mount flags in /etc/fstab:

ro,nfsv4,minorversion=3D2,tcp,nosuid,noatime,nolockd,oneopenown

Is there anything more we can do to help identify this issue?

Thanks for any advice!



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