note, as visible in the dmesg log, IO attempts with another unrelated USB device (the USB stick ubuntu had previously booted from) failed, causing IO errors, as the entire USB subsystem was down.
this is also why I had to submit this bug with "ubuntu-bug" prior to actually causing the bug and upload the dmesg.log later, since ubuntu- bug would no longer be able to work after the OOPS happened. like with Ubuntu 18 this bug has the potential to cause data loss, make the system unstable, and a hard reboot is required to recover -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1905994 Title: failure to set dtr/rts on USB VCP causes kernel page fault Status in linux package in Ubuntu: Confirmed Bug description: attempting to reproduce bug https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1905782 on ubuntu 20.04.1 LTS yields a kernel OOOPS / page fault in the USB cdc_acm driver. will upload OOOPs shortly. steps to reproduce: 1. boot ubuntu 20.04.1 LTS (In this case from live CD) 2. plug in a USB device with a virtual com port 3. configure the TTY assigned (/dev/ttyACM0) setting dtr/rts (for example with minicom) 4. device does not support setting dtr/rts expected result: error message actual result: error message plus page fault in kernel space plus system becoming unstable will upload and attach dmesg log as soon as I managed to log the oops ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: linux-image-5.4.0-42-generic 5.4.0-42.46 ProcVersionSignature: Ubuntu 5.4.0-42.46-generic 5.4.44 Uname: Linux 5.4.0-42-generic x86_64 NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair ApportVersion: 2.20.11-0ubuntu27.4 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: ubuntu 4492 F.... pulseaudio CasperMD5CheckMismatches: ./casper/filesystem.squashfs CasperMD5CheckResult: skip CasperVersion: 1.445.1 CurrentDesktop: ubuntu:GNOME Date: Fri Nov 27 17:37:22 2020 LiveMediaBuild: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731) MachineType: FUJITSU LIFEBOOK E736 ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/username.seed maybe-ubiquity quiet splash --- RelatedPackageVersions: linux-restricted-modules-5.4.0-42-generic N/A linux-backports-modules-5.4.0-42-generic N/A linux-firmware 1.187.2 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 12/20/2016 dmi.bios.vendor: FUJITSU // Insyde Software Corp. dmi.bios.version: Version 1.22 dmi.board.name: FJNB293 dmi.board.vendor: FUJITSU dmi.board.version: M4 dmi.chassis.type: 10 dmi.chassis.vendor: FUJITSU dmi.chassis.version: LIFEBOOK E736 dmi.modalias: dmi:bvnFUJITSU//InsydeSoftwareCorp.:bvrVersion1.22:bd12/20/2016:svnFUJITSU:pnLIFEBOOKE736:pvr10601115935:rvnFUJITSU:rnFJNB293:rvrM4:cvnFUJITSU:ct10:cvrLIFEBOOKE736: dmi.product.family: LIFEBOOK-FTS dmi.product.name: LIFEBOOK E736 dmi.product.version: 10601115935 dmi.sys.vendor: FUJITSU To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1905994/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
