sudo fails and Kernel bug

[hans12345]

I have my Ubuntu 20.04 failing after about an hour of use. It is not quite dead but not usable. It will not shutdown and has to be forcibly powered off and restarted. Then it works again for a while.

Initially my Internet connection dies. I have been poking around. I find the network-manager is not running. I try a sudo command but sudo does not work. It does not even ask for my password. No command starting with sudo works.

I look at the system log (sorry not attached here since I'm forced to report this on an old Win10 PC, which at least has Internet) and I see:
kernel: kernel BUG at mm/slub.c:306!

Any ideas? What should I be looking for? What can I post to make things clearer?

Help!

[hans12345]

I have rebooted and am on the Ubuntu PC again. Now I can post the key part of the system log around the kernel bug :

08:19:14 kernel: Modules linked in: ccm intel_rapl_msr usblp mei_hdcp intel_rapl_common x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_hda_codec_hdmi snd_hda_intel crct10dif_pclmul snd_intel_dspcfg snd_hda_codec ghash_clmulni_intel snd_hda_core snd_hwdep ath9k_htc snd_pcm amdgpu ath9k_common snd_seq_midi snd_seq_midi_event aesni_intel ath9k_hw crypto_simd cryptd glue_helper ath intel_cstate snd_rawmidi intel_rapl_perf amd_iommu_v2 snd_seq mac80211 eeepc_wmi asus_wmi sparse_keymap input_leds wmi_bmof gpu_sched serio_raw snd_seq_device mxm_wmi ttm snd_timer drm_kms_helper snd i2c_algo_bit fb_sys_fops cfg80211 syscopyarea sysfillrect soundcore libarc4 sysimgblt mei_me mei mac_hid acpi_pad sch_fq_codel parport_pc ppdev lp parport drm ip_tables x_tables autofs4 uas usb_storage nvme ahci r8169 crc32_pclmul psmouse i2c_i801 nvme_core realtek libahci wmi video
08:19:14 kernel:  ret_from_fork+0x35/0x40
08:19:14 kernel: Call Trace:
08:19:14 kernel: CR2: 000055eb5f768978 CR3: 0000000318c0a005 CR4: 00000000003606e0
08:19:14 kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
08:19:14 kernel: FS:  0000000000000000(0000) GS:ffff98eb66b00000(0000) knlGS:0000000000000000
08:19:14 kernel: R13: ffff98eb64c02e00 R14: ffffffff88518c35 R15: ffffae638050bd48
08:19:14 kernel: R10: ffff98eb66b29a00 R11: ffff98eb66b299e0 R12: fffffa3a50697800
08:19:14 kernel: RBP: ffffae638050bc70 R08: ffff98eb5a5e0600 R09: 0000000000000000
08:19:14 kernel: RDX: 000000000003ea42 RSI: 0000000000000246 RDI: ffff98eb5a5e0600
08:19:14 kernel: RAX: ffff98eb5a5e0600 RBX: ffff98eb5a5e0600 RCX: ffff98eb5a5e0600
08:19:14 kernel: RSP: 0018:ffffae638050bc50 EFLAGS: 00010246
08:19:14 kernel: Code: e7 e8 fe 68 fd ff e9 ef fe ff ff 4d 89 f1 41 b8 01 00 00 00 48 89 d9 48 89 da 4c 89 e6 4c 89 ef e8 9f fa ff ff e9 d0 fe ff ff <0f> 0b 48 8b 05 b1 ab 36 01 e9 ff fd ff ff 66 66 2e 0f 1f 84 00 00
08:19:14 kernel: RIP: 0010:kfree+0x236/0x250
08:19:14 kernel: Workqueue: phy0 ath9k_htc_ani_work [ath9k_htc]
08:19:14 kernel: Hardware name: System manufacturer System Product Name/PRIME B250M-A, BIOS 0614 04/18/2017
08:19:14 kernel: CPU: 2 PID: 260 Comm: kworker/u8:4 Not tainted 5.4.0-42-generic #46-Ubuntu
08:19:14 kernel: invalid opcode: 0000 [#1] SMP PTI
08:19:14 kernel: kernel BUG at mm/slub.c:306!
08:19:14 kernel: ------------[ cut here ]------------
08:19:14 kernel: wlx74ea3a8f3e6d: deauthenticating from 8c:3b:ad:fc:81:66 by local choice (Reason: 3=DEAUTH_LEAVING)
08:19:14 kernel: usb 1-6: USB disconnect, device number 2

A further minor note.
When I try to log off and power down, I am left with a black screen with "Ubuntu" written in large white letters at the bottom. This just stays until I hold the power switch off for a while.

[hans12345]

I had a further crash today. This was a hard one. Screen just froze. Had to do a forced power off.

Key log files at the time of the crash (about 15.30):

Syslog:
Aug 18 14:30:36 Arctic systemd[1]: Started Run anacron jobs.
Aug 18 14:30:36 Arctic anacron[4645]: Anacron 2.3 started on 2020-08-18
Aug 18 14:30:36 Arctic anacron[4645]: Normal exit (0 jobs run)
Aug 18 14:30:36 Arctic systemd[1]: anacron.service: Succeeded.
Aug 18 15:01:50 Arctic systemd[1]: Starting Refresh fwupd metadata and update motd...
Aug 18 15:01:50 Arctic systemd[1]: fwupd-refresh.service: Succeeded.
Aug 18 15:01:50 Arctic systemd[1]: Finished Refresh fwupd metadata and update motd.
Aug 18 15:08:16 Arctic wpa_supplicant[982]: wlx74ea3a8f3e6d: WPA: Group rekeying completed with 8c:3b:ad:fc:81:66 [GTK=TKIP]
Aug 18 15:10:32 Arctic wpa_supplicant[982]: wlx74ea3a8f3e6d: CTRL-EVENT-SIGNAL-CHANGE above=0 signal=-74 noise=9999 txrate=243000
Aug 18 15:10:40 Arctic wpa_supplicant[982]: wlx74ea3a8f3e6d: CTRL-EVENT-SIGNAL-CHANGE above=1 signal=-66 noise=9999 txrate=270000
Aug 18 15:11:52 Arctic wpa_supplicant[982]: wlx74ea3a8f3e6d: CTRL-EVENT-SIGNAL-CHANGE above=1 signal=-60 noise=9999 txrate=300000
Aug 18 15:14:40 Arctic wpa_supplicant[982]: wlx74ea3a8f3e6d: CTRL-EVENT-SIGNAL-CHANGE above=1 signal=-54 noise=9999 txrate=243000
Aug 18 15:17:01 Arctic CRON[5012]: (root) CMD (   cd / && run-parts --report /etc/cron.hourly)
Aug 18 15:30:01 Arctic CRON[5094]: (root) CMD ([ -x /etc/init.d/anacron ] && if [ ! -d /run/systemd/system ]; then /usr/sbin/invoke-rc.d anacron start >/dev/null; fi)
auth log:
Aug 18 14:17:01 Arctic CRON[4531]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 18 14:17:01 Arctic CRON[4531]: pam_unix(cron:session): session closed for user root
Aug 18 14:30:01 Arctic CRON[4640]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 18 14:30:01 Arctic CRON[4640]: pam_unix(cron:session): session closed for user root
Aug 18 15:17:01 Arctic CRON[5011]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 18 15:17:01 Arctic CRON[5011]: pam_unix(cron:session): session closed for user root
Aug 18 15:30:01 Arctic CRON[5093]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 18 15:30:01 Arctic CRON[5093]: pam_unix(cron:session): session closed for user root
kern log has nothing at the time of the crash

Your help and advice appreciated

[Doug S]

I wonder if this is your issue?
The fix is already in the mainline kernels, but may not have worked its way back to Ubuntu kernel 5.4 yet. Seems to be in upstream 5.4.47
I did not look for a launchpad version of the bug report.

[ActionParsnip]

What happens when you use sudo? What is output in the terminal? Use a simple command like

sudo ls

[hans12345]

Thanks Doug, thanks Action.

Action: that first partial crash I tried 'sudo ls' and got nothing, not even the request for the PW.

But today's freeze crash was quite different. The PC just froze. And the logs are different - no 'kernel bug'.

I am wondering if this is a HW problem? If it is, how can I track it down? Where should I be looking?

Thanks for your help.

[TheFu]

First, a lockup of the GUI isn't necessarily a system lockup. Have you tried switching to a different console or ssh'ing into the system using a different machine? Do both of those fail?

As for HW issues,

egrep -i 'err|warn' /var/log/*g

and check the dmesg output for errors and warnings too. There's a way to do that with journalctl, but I don't use that.

The hardest things to troubleshoot are failing power supplies. Many PC shops will test a PSU for free. Just take it in.

Of course, it could be a kernel bug too.

Perhaps an overview of the hardware would help us? Run this inxi -Fxxpzc0
If the network isn't working, please use sneaker-net to copy the text output to a flash drive, then copy that from Windows to these forums and wrap it in 'code tags' using the Advanced Edit option. Otherwise, it is just too hard to read the output.

[Doug S]

As a test, try the mainline kernel.

[hans12345]

Output from inxi -Fxxxpzc0 (extra x option chosen from askubuntu advice):

System:    Kernel: 5.4.0-42-generic x86_64 bits: 64 compiler: gcc v: 9.3.0 Desktop: Gnome 3.36.3 wm: gnome-shell 
           dm: GDM3 3.34.1 Distro: Ubuntu 20.04.1 LTS (Focal Fossa) 
Machine:   Type: Desktop Mobo: ASUSTeK model: PRIME B250M-A v: Rev X.0x serial: <filter> UEFI [Legacy]: American Megatrends 
           v: 0614 date: 04/18/2017 
CPU:       Topology: Dual Core model: Intel Pentium G4560 bits: 64 type: MT MCP arch: Kaby Lake rev: 9 L2 cache: 3072 KiB 
           flags: lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 27999 
           Speed: 800 MHz min/max: 800/3500 MHz Core speeds (MHz): 1: 800 2: 800 3: 800 4: 800 
Graphics:  Device-1: AMD Lexa PRO [Radeon 540/540X/550/550X / RX 540X/550/550X] vendor: Sapphire Limited driver: amdgpu 
           v: kernel bus ID: 01:00.0 chip ID: 1002:699f 
           Display: x11 server: X.Org 1.20.8 driver: amdgpu compositor: gnome-shell resolution: 1920x1080~60Hz 
           OpenGL: renderer: Radeon RX550/550 Series (POLARIS12 DRM 3.35.0 5.4.0-42-generic LLVM 10.0.0) v: 4.6 Mesa 20.0.8 
           direct render: Yes 
Audio:     Device-1: Intel 200 Series PCH HD Audio vendor: ASUSTeK driver: snd_hda_intel v: kernel bus ID: 00:1f.3 
           chip ID: 8086:a2f0 
           Device-2: AMD Baffin HDMI/DP Audio [Radeon RX 550 640SP / RX 560/560X] vendor: Sapphire Limited 
           driver: snd_hda_intel v: kernel bus ID: 01:00.1 chip ID: 1002:aae0 
           Sound Server: ALSA v: k5.4.0-42-generic 
Network:   Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet vendor: ASUSTeK driver: r8169 v: kernel port: d000 
           bus ID: 03:00.0 chip ID: 10ec:8168 
           IF: enp3s0 state: up speed: 100 Mbps duplex: full mac: <filter> 
           Device-2: Qualcomm Atheros TP-Link TL-WN821N v3 / TL-WN822N v2 802.11n [Atheros AR7010+AR9287] type: USB 
           driver: ath9k_htc bus ID: 1-6:2 chip ID: 0cf3:7015 serial: <filter> 
           IF: wlx74ea3a8f3e6d state: up mac: <filter> 
Drives:    Local Storage: total: 1.57 TiB used: 265.87 GiB (16.5%) 
           ID-1: /dev/nvme0n1 vendor: Corsair model: Force MP510 size: 447.13 GiB speed: 31.6 Gb/s lanes: 4 serial: <filter> 
           rev: ECFM12.2 scheme: GPT 
           ID-2: /dev/sda vendor: Samsung model: SP2504C size: 232.89 GiB speed: 3.0 Gb/s serial: <filter> rev: 0-50 
           scheme: MBR 
           ID-3: /dev/sdb vendor: Western Digital model: WD10EZEX-08WN4A0 size: 931.51 GiB speed: 6.0 Gb/s rotation: 7200 rpm 
           serial: <filter> rev: 1A01 scheme: GPT 
Partition: ID-1: / size: 95.62 GiB used: 13.90 GiB (14.5%) fs: ext4 dev: /dev/nvme0n1p1 
           ID-2: /home size: 342.99 GiB used: 251.96 GiB (73.5%) fs: ext4 dev: /dev/nvme0n1p2 
           ID-3: /snap/chromium/1244 raw size: 158.4 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop2 
           ID-4: /snap/chromium/1260 raw size: 158.4 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop5 
           ID-5: /snap/core/9665 raw size: 97.0 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop10 
           ID-6: /snap/core/9804 raw size: 96.6 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop6 
           ID-7: /snap/core18/1880 raw size: 55.0 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop0 
           ID-8: /snap/core18/1885 raw size: 55.3 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop1 
           ID-9: /snap/firefox/392 raw size: 145.0 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop3 
           ID-10: /snap/firefox/398 raw size: 163.2 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop15 
           ID-11: /snap/gnome-3-28-1804/116 raw size: 160.2 MiB size: <superuser/root required> 
           used: <superuser/root required> fs: squashfs dev: /dev/loop4 
           ID-12: /snap/gnome-3-28-1804/128 raw size: 161.4 MiB size: <superuser/root required> 
           used: <superuser/root required> fs: squashfs dev: /dev/loop13 
           ID-13: /snap/gnome-3-34-1804/33 raw size: 255.6 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop12 
           ID-14: /snap/gnome-3-34-1804/36 raw size: 255.6 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop7 
           ID-15: /snap/gtk-common-themes/1502 raw size: 54.8 MiB size: <superuser/root required> 
           used: <superuser/root required> fs: squashfs dev: /dev/loop19 
           ID-16: /snap/gtk-common-themes/1506 raw size: 62.1 MiB size: <superuser/root required> 
           used: <superuser/root required> fs: squashfs dev: /dev/loop8 
           ID-17: /snap/signal-desktop/326 raw size: 114.2 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop9 
           ID-18: /snap/signal-desktop/327 raw size: 114.3 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop20 
           ID-19: /snap/skype/139 raw size: 177.2 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop11 
           ID-20: /snap/skype/143 raw size: 177.4 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop21 
           ID-21: /snap/snap-store/415 raw size: 43.2 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop18 
           ID-22: /snap/snap-store/467 raw size: 49.8 MiB size: <superuser/root required> used: <superuser/root required> 
           fs: squashfs dev: /dev/loop16 
           ID-23: /snap/speedy-duplicate-finder/26 raw size: 59.2 MiB size: <superuser/root required> 
           used: <superuser/root required> fs: squashfs dev: /dev/loop14 
           ID-24: /snap/speedy-duplicate-finder/27 raw size: 59.2 MiB size: <superuser/root required> 
           used: <superuser/root required> fs: squashfs dev: /dev/loop17 
           ID-25: swap-1 size: 3.23 GiB used: 0 KiB (0.0%) fs: swap dev: /dev/sda6 
           ID-26: swap-2 size: 7.87 GiB used: 0 KiB (0.0%) fs: swap dev: /dev/sdb6 
Sensors:   System Temperatures: cpu: 46.0 C mobo: N/A gpu: amdgpu temp: 29 C 
           Fan Speeds (RPM): N/A gpu: amdgpu fan: 1167 
Info:      Processes: 268 Uptime: 1h 11m Memory: 15.58 GiB used: 4.69 GiB (30.1%) Init: systemd v: 245 runlevel: 5 Compilers: 
           gcc: 9.3.0 alt: 9 Shell: bash v: 5.0.17 running in: gnome-terminal inxi: 3.0.38

[hans12345]

3 errors in dmesg.0 (I cannot understand the layout timewise, so cannot link these to the time of the crash):

[    0.198709] kernel: acpi PNP0A08:00: _OSC failed (AE_ERROR); disabling ASPM
[    0.365961] kernel: RAS: Correctable Errors collector initialized.
[    2.279911] kernel: EXT4-fs (nvme0n1p1): re-mounted. Opts: errors=remount-ro