Public bug reported:
Copying a large file using cp on my Raspberry Pi 3B (not 3B+) from an
externally-powered USB hard disk (Seagate Expansion 2TB) to an NFS-
mounted filesystem across Ethernet causes the kernel of releases 19.10
and 20.04 to hang/freeze.
This happens every time the copy is attempted, although the exact
duration from the start of the copy to the hang varies from a few
seconds to a couple of minutes. The kernel does not recover even after
long waits (30mins+), and a power reset (pulling the plug) is required.
(Although I admit I haven't tried yet simply disconnecting the USB cable
of the HDD during a hang.)
Likewise, messages are erratic and I suspect are only symptoms, notably
watchdog BUG soft lockup messages and RCU stall messages on different
CPU cores for different processes/threads. There are no hardware
messages that I've seen recorded in log files (or appearing on the
console) matching the incidents.
Although I have had a swapfile configured on the SD card, the hang
continues to happen doing the cp after "swapoff -a". I've also tried
playing with taskset affinities and snappiness to no obvious effect -
the hangs still keep happening.
Copying from the external HDD to the SD card is successful, as is
copying from the SD card to the NFS.
Raspbian 4.19.0-8 (armmp-lpae) does not have this problem; it
successfully copies the file from HDD to NFS across Ethernet without
stalling.
ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-image-5.4.0-1011-raspi 5.4.0-1011.11
ProcVersionSignature: Ubuntu 5.4.0-1011.11-raspi 5.4.34
Uname: Linux 5.4.0-1011-raspi aarch64
ApportVersion: 2.20.11-0ubuntu27
Architecture: arm64
CasperMD5CheckResult: skip
Date: Fri Jun 5 07:37:44 2020
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
LANG=C.UTF-8
SHELL=/bin/bash
SourcePackage: linux-raspi
UpgradeStatus: Upgraded to focal on 2020-05-21 (14 days ago)
** Affects: linux-raspi (Ubuntu)
Importance: Undecided
Status: New
** Tags: apport-bug arm64 focal third-party-packages uec-images
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https://bugs.launchpad.net/bugs/1882213
Title:
cp file from external HDD to NFS on Pi 3B causes ubuntu 19.10 and
20.04 kernel to hang
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