there is overlayfs in the middle of the stack dump, so I think this is the place to post. happy to post it somewhere else if directed. currently very reproducible - 3 times in a row, rebooting both clent and server between. tt may be related to me setting nfsvers=3. I plan on testing this guess, but it may be a while. hours or maybe a day or 2. I tried to pin down the file operation client side, but that hasn't happened yet either. client and server Details: server: raspberry pi v3, pi@rpi-cb-1f-f7:~$ uname -a Linux rpi-cb-1f-f7 5.10.63-v7+ #1488 SMP Thu Nov 18 16:14:44 GMT 2021 armv7l GNU/Linux pi@rpi-cb-1f-f7:~$ cat /etc/exports /srv/nfs/rpi/bullseye/root/merged *(rw,sync,no_subtree_check,no_root_squash,fsid=2) pi@rpi-cb-1f-f7:~$ findmnt /srv/nfs/rpi/bullseye/root/merged | cat TARGET SOURCE FSTYPE OPTIONS /srv/nfs/rpi/bullseye/root/merged overlay overlay rw,relatime,lowerdir=/srv/nfs/rpi/bullseye/root/setup:/srv/nfs/rpi/bullseye/root/base,upperdir=/srv/nfs/rpi/bullseye/root/updates,workdir=/srv/nfs/rpi/bullseye/root/work,index=on,nfs_export=on pi@rpi-cb-1f-f7:~$ findmnt / TARGET SOURCE FSTYPE OPTIONS / /dev/mmcblk0p2 ext4 rw,noatime client: also a pi: pi@raspberrypi:~ $ uname -a Linux raspberrypi 5.10.63-v8+ #1488 SMP PREEMPT Thu Nov 18 16:16:16 GMT 2021 aarch64 GNU/Linux root@raspberrypi:~# cat /etc/fstab # proc /proc proc defaults 0 0 10.21.0.1:/srv/nfs/rpi/bullseye/root/merged / nfs defaults,auto,rw,nfsvers=3 0 0 root@raspberrypi:~# findmnt /|cat / 10.21.0.1:/srv/nfs/rpi/bullseye/root/merged nfs rw,relatime,vers=3,rsize=4096,wsize=4096,namlen=255,hard,nolock,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=10.21.0.1,mountvers=3,mountproto=tcp,local_lock=all,addr=10.21.0.1 on the client, I run apt autoremove --assume-yes [ 1103.834869] INFO: task nfsd:1029 blocked for more than 122 seconds. [ 1103.834889] Tainted: G C 5.10.63-v7+ #1488 [ 1103.834901] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1103.834915] task:nfsd state:D stack: 0 pid: 1029 ppid: 2 flags:0x00000000 [ 1103.834945] Backtrace: [ 1103.834992] [<809f9df0>] (__schedule) from [<809fa7c8>] (schedule+0x68/0xe4) [ 1103.835015] r10:00000000 r9:86f67d4c r8:8fc134a0 r7:00000002 r6:00000001 r5:86dc4d80 [ 1103.835029] r4:ffffe000 [ 1103.835056] [<809fa760>] (schedule) from [<8017bcac>] (rwsem_down_write_slowpath+0x318/0x518) [ 1103.835072] r5:ffffe000 r4:8fc13490 [ 1103.835094] [<8017b994>] (rwsem_down_write_slowpath) from [<809fd700>] (down_write+0x6c/0x70) [ 1103.835116] r10:7f0f2df4 r9:00000000 r8:8c696bb0 r7:82ba73d0 r6:85d00600 r5:8fc13490 [ 1103.835129] r4:8fc13490 [ 1103.835195] [<809fd694>] (down_write) from [<7f6676b8>] (ovl_dir_release+0x34/0x70 [overlay]) [ 1103.835211] r5:8fc13490 r4:96d1eb80 [ 1103.835267] [<7f667684>] (ovl_dir_release [overlay]) from [<803359f0>] (__fput+0x90/0x25c) [ 1103.835286] r7:82ba73d0 r6:000a841d r5:8fc13408 r4:85d00600 [ 1103.835307] [<80335960>] (__fput) from [<80335c24>] (delayed_fput+0x4c/0x58) [ 1103.835328] r9:8fc13408 r8:00000122 r7:00000100 r6:80f05008 r5:86f67e34 r4:85d00180 [ 1103.835348] [<80335bd8>] (delayed_fput) from [<80335c4c>] (flush_delayed_fput+0x1c/0x20) [ 1103.835363] r5:86f67e34 r4:00000001 [ 1103.835570] [<80335c30>] (flush_delayed_fput) from [<7f0c7ec4>] (nfsd_file_close_inode_sync+0x180/0x188 [nfsd]) [ 1103.835916] [<7f0c7d44>] (nfsd_file_close_inode_sync [nfsd]) from [<7f0c065c>] (nfsd_unlink+0x230/0x270 [nfsd]) [ 1103.835938] r8:ffffc000 r7:92419068 r6:86f44000 r5:937dd3b8 r4:86fa0008 [ 1103.836285] [<7f0c042c>] (nfsd_unlink [nfsd]) from [<7f0ca3f4>] (nfsd3_proc_remove+0x80/0xd8 [nfsd]) [ 1103.836308] r9:00000018 r8:96dd5000 r7:86f44000 r6:86fa0008 r5:86fa0000 r4:86f38000 [ 1103.836650] [<7f0ca374>] (nfsd3_proc_remove [nfsd]) from [<7f0b973c>] (nfsd_dispatch+0xc8/0x14c [nfsd]) [ 1103.836669] r7:96dd5014 r6:7f0f2df4 r5:86f45000 r4:86f44000 [ 1103.836856] [<7f0b9674>] (nfsd_dispatch [nfsd]) from [<809ca22c>] (svc_process_common+0x374/0x70c) [ 1103.836878] r9:86f45000 r8:86f45a20 r7:86f44000 r6:80f05008 r5:00000014 r4:86f44184 [ 1103.836901] [<809c9eb8>] (svc_process_common) from [<809ca69c>] (svc_process+0xd8/0xec) [ 1103.836923] r10:856abcfc r9:86f44000 r8:81016540 r7:7f100bc4 r6:816cae00 r5:bab24000 [ 1103.836937] r4:86f44000 [ 1103.837120] [<809ca5c4>] (svc_process) from [<7f0b9100>] (nfsd+0xf4/0x164 [nfsd]) [ 1103.837135] r5:00057e40 r4:86f44000 [ 1103.837321] [<7f0b900c>] (nfsd [nfsd]) from [<80143790>] (kthread+0x170/0x174) [ 1103.837342] r9:86f44000 r8:7f0b900c r7:86f66000 r6:00000000 r5:892b9580 r4:847acbc0 [ 1103.837364] [<80143620>] (kthread) from [<801000ec>] (ret_from_fork+0x14/0x28) [ 1103.837378] Exception stack(0x86f67fb0 to 0x86f67ff8) [ 1103.837396] 7fa0: 00000000 00000000 00000000 00000000 [ 1103.837415] 7fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 [ 1103.837434] 7fe0: 00000000 00000000 00000000 00000000 00000013 00000000 [ 1103.837454] r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:80143620 [ 1103.837467] r4:892b9580 -- Carl K
