connection to a nfs volume from a client freezes the whole server randomly

[no!chance]

This behaviour occured since the beginning of july. First I tried Ubuntu 20.04 on my notebook and I experienced this problem. Therefore I thought, that ubunut 20.04 nfs client and 18.04 nfs server where incompatible in some kind. Then I reinstalled Ubuntu 18.04 on my notebook. But the problem still exists.

I'm running kernel 5.3 on both client and server. I use the package autofs for mounting volumes.

Because the system crashes, I could not find any logs.

Any hint what I should do, finding this error. Thank you!

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: nfs-kernel-server 1:1.3.4-2.1ubuntu5.3
ProcVersionSignature: Ubuntu 5.3.0-62.56~18.04.1-generic 5.3.18
Uname: Linux 5.3.0-62-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.9-0ubuntu7.15
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sat Jul 11 19:28:28 2020
InstallationDate: Installed on 2018-01-21 (902 days ago)
InstallationMedia: Ubuntu 16.04.3 LTS "Xenial Xerus" - Release amd64 (20170801)
SourcePackage: nfs-utils
UpgradeStatus: Upgraded to bionic on 2020-01-10 (183 days ago)

[Jani Jaakkola (jj-lousa)]

Just saw this on 5.3.0-62-generic on 18.04. When this happens, kernel gets a stack trace on BUG. The problem is not in nfs-utils, but a new bug in kernel, likely exactly kernel version 5.3.0-62-generic, since this popped up right after kernel update.

Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681409] BUG: unable to handle page fault for address: ffff90f1ce3b673e
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681414] #PF: supervisor read access in kernel mode
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681414] #PF: error_code(0x0000) - not-present page
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681415] PGD b3402067 P4D b3402067 PUD 0
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681418] Oops: 0000 [#1] SMP PTI
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681420] CPU: 0 PID: 3777 Comm: kworker/u4:2 Not tainted 5.3.0-62-generic #56~18.04.1-Ubuntu
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681421] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 12/12/
2018
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681441] Workqueue: rpciod rpc_async_schedule [sunrpc]
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681474] RIP: 0010:kmem_cache_alloc+0x7e/0x220
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681476] Code: ba 01 00 00 4d 8b 07 65 49 8b 50 08 65 4c 03 05 80 29 57 5e 4d 8b 20 4d 85 e4 0f 84 66 01 00 00
41 8b 47 20 49 8b 3f 4c 01 e0 <48> 8b 18 49 33 9f 70 01 00 00 48 89 c1 48 0f c9 4c 89 e0 48 31 cb
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681477] RSP: 0018:ffffb4a7036dbcd8 EFLAGS: 00010282
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681478] RAX: ffff90f1ce3b673e RBX: 0000000000092800 RCX: 0000000000000002
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681479] RDX: 000000000000002c RSI: 0000000000092800 RDI: 0000000000031d70
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681480] RBP: ffffb4a7036dbd08 R08: ffff90f17aa31d70 R09: 8080808080808080
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681480] R10: ffffffffa2e03d10 R11: fefefefefefefeff R12: ffff90f1ce3b673e
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681481] R13: 0000000000092800 R14: ffff90f17999e000 R15: ffff90f17999e000
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681482] FS: 0000000000000000(0000) GS:ffff90f17aa00000(0000) knlGS:0000000000000000
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681483] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681484] CR2: ffff90f1ce3b673e CR3: 0000000136de0004 CR4: 00000000003606f0
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681512] Call Trace:
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681522] ? mempool_alloc_slab+0x15/0x20
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681537] ? wait_woken+0x80/0x80
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681539] mempool_alloc_slab+0x15/0x20
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681540] mempool_alloc+0x71/0x190
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681548] rpc_malloc+0x9d/0xd0 [sunrpc]
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681555] call_allocate+0xbb/0x1f0 [sunrpc]
Jul 13 13:04:10 vdi-cubic-022 kernel: [ 3140.681560] ? call_refreshresult+0x140/0x140 [sunrpc]
Jul 13 13:04:10 vdi-cubic-022 ker...

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.