I have had 3 hangs between 24 March and 1 April. All were when I was out and about, so I couldn't SSH into the machine. Today, I had a couple of hangs occur with no apparent cause. Disk activity continued. But, I couldn't SSH into the machine. I killed the machine (during a hang) at 8:35:51 am. I restarted it at 9:14:04 am. It crashed again. I checked /var/crash, and it had the following (I've inserted the file contents below listed files): [ gary@Quasar | Tue 02 Apr 2019 10:11am ] ~ >dir /var/crash total 16 drwxrwsrwt 2 root whoopsie 4096 Apr 2 09:47 ./ drwxr-xr-x 14 root root 4096 Feb 9 19:20 ../ ---------- 1 root whoopsie 0 Apr 2 08:36 _lib_systemd_systemd-logind.0.crash -rw-r--r-- 1 kernoops whoopsie 2324 Apr 2 09:45 linux-image-4.18.0-16-generic.157976.crash ProblemType: KernelOops Annotation: Your system might become unstable now and might need to be restarted. Date: Tue Apr 2 09:45:56 2019 Failure: oops OopsText: watchdog: BUG: soft lockup - CPU#4 stuck for 22s! [pool:2748] Modules linked in: rfcomm ccm bnep arc4 iwldvm snd_hda_codec_hdmi mac80211 intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp btusb btrtl btbcm btintel kvm bluetooth snd_hda_codec_conexant snd_hda_codec_generic snd_hda_intel snd_hda_codec gpio_ich thinkpad_acpi snd_hda_core snd_hwdep snd_pcm iwlwifi nvram snd_seq_midi snd_seq_midi_event ecdh_generic cfg80211 snd_rawmidi snd_seq snd_seq_device snd_timer snd soundcore mei_me mei lpc_ich irqbypass intel_cstate intel_rapl_perf input_leds mac_hid serio_raw wmi_bmof sch_fq_codel parport_pc ppdev lp parport ip_tables x_tables autofs4 algif_skcipher af_alg dm_crypt crct10dif_pclmul nouveau crc32_pclmul ghash_clmulni_intel mxm_wmi pcbc i2c_algo_bit ttm drm_kms_helper aesni_intel aes_x86_64 syscopyarea crypto_simd sysfillrect cryptd sysimgblt fb_sys_fops glue_helper firewire_ohci sdhci_pci cqhci psmouse drm sdhci ahci e1000e firewire_core libahci crc_itu_t wmi video CPU: 4 PID: 2748 Comm: pool Tainted: G L 4.18.0-16-generic #17~18.04.1-Ubuntu Hardware name: LENOVO 4260A45/4260A45, BIOS 8BET66WW (1.46 ) 06/14/2018 RIP: 0010:smp_call_function_many+0x22c/0x250 Code: 75 8a 00 3b 05 c9 8c 55 01 0f 83 5c fe ff ff 48 63 c8 48 8b 13 48 03 14 cd 00 37 9c b8 8b 4a 18 83 e1 01 74 0a f3 90 8b 4a 18 <83> e1 01 75 f6 eb c7 48 c7 c2 60 60 e8 b8 4c 89 e6 89 c7 e8 cc 75 RSP: 0018:ffffb9f488e47c88 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000007 RBX: ffff9dd0bdd23b80 RCX: 0000000000000003 RDX: ffff9dd0bdde8de0 RSI: 0000000000000000 RDI: ffff9dd0ad028ef8 RBP: ffffb9f488e47cc0 R08: 0000000000027040 R09: ffffffffb81d5449 R10: ffffdab51060f780 R11: 0000000000000148 R12: 0000000000000008 R13: 0000000000023b40 R14: ffffffffb787d920 R15: ffffb9f488e47d00 FS: 00007f9025bff700(0000) GS:ffff9dd0bdd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9025be6ff8 CR3: 00000004268de002 CR4: 00000000000606e0 Call Trace: Package: linux-image-4.18.0-16-generic 4.18.0-16.17~18.04.1 SourcePackage: linux Tags: kernel-oops Uname: Linux 4.18.0-16-generic x86_64 -rw-r--r-- 1 kernoops whoopsie 2317 Apr 2 09:43 linux-image-4.18.0-16-generic.158329.crash ProblemType: KernelOops Annotation: Your system might become unstable now and might need to be restarted. Date: Tue Apr 2 09:43:57 2019 Failure: oops OopsText: watchdog: BUG: soft lockup - CPU#6 stuck for 22s! [thermald:1144] Modules linked in: rfcomm ccm bnep arc4 iwldvm snd_hda_codec_hdmi mac80211 intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp btusb btrtl btbcm btintel kvm bluetooth snd_hda_codec_conexant snd_hda_codec_generic snd_hda_intel snd_hda_codec gpio_ich thinkpad_acpi snd_hda_core snd_hwdep snd_pcm iwlwifi nvram snd_seq_midi snd_seq_midi_event ecdh_generic cfg80211 snd_rawmidi snd_seq snd_seq_device snd_timer snd soundcore mei_me mei lpc_ich irqbypass intel_cstate intel_rapl_perf input_leds mac_hid serio_raw wmi_bmof sch_fq_codel parport_pc ppdev lp parport ip_tables x_tables autofs4 algif_skcipher af_alg dm_crypt crct10dif_pclmul nouveau crc32_pclmul ghash_clmulni_intel mxm_wmi pcbc i2c_algo_bit ttm drm_kms_helper aesni_intel aes_x86_64 syscopyarea crypto_simd sysfillrect cryptd sysimgblt fb_sys_fops glue_helper firewire_ohci sdhci_pci cqhci psmouse drm sdhci ahci e1000e firewire_core libahci crc_itu_t wmi video CPU: 6 PID: 1144 Comm: thermald Not tainted 4.18.0-16-generic #17~18.04.1-Ubuntu Hardware name: LENOVO 4260A45/4260A45, BIOS 8BET66WW (1.46 ) 06/14/2018 RIP: 0010:smp_call_function_single+0xdc/0x100 Code: 00 00 00 75 40 48 83 c4 48 41 5a 5d 49 8d 62 f8 c3 48 89 d1 48 89 f2 48 8d 75 b0 e8 6e fe ff ff 8b 55 c8 83 e2 01 74 0a f3 90 <8b> 55 c8 83 e2 01 75 f6 eb c2 8b 05 04 af 85 01 85 c0 75 81 0f 0b RSP: 0018:ffffb9f48314fc40 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000000 RBX: ffffb9f48314fcfc RCX: 0000000000000000 RDX: 0000000000000001 RSI: 00000000000000fb RDI: 0000000000000282 RBP: ffffb9f48314fc90 R08: ffff9dd0a7985828 R09: ffff9dd09b849d80 R10: ffffb9f48314fcb0 R11: 0000000000002000 R12: ffffb9f48314fcf8 R13: ffff9dd0a7985bb0 R14: ffffb9f48314fd74 R15: ffff9dd0484a4d80 FS: 00007fb3bfe85700(0000) GS:ffff9dd0bdd80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00003b41368e3000 CR3: 0000000416f2c004 CR4: 00000000000606e0 Call Trace: Package: linux-image-4.18.0-16-generic 4.18.0-16.17~18.04.1 SourcePackage: linux Tags: kernel-oops Uname: Linux 4.18.0-16-generic x86_64 -rw-r--r-- 1 kernoops whoopsie 0 Apr 2 09:47 linux-image-4.18.0-16-generic.158709.crash -rw-r--r-- 1 kernoops whoopsie 0 Apr 2 08:36 linux-image-4.18.0-16-generic.176983.crash -rw-r--r-- 1 kernoops whoopsie 0 Apr 2 08:36 linux-image-4.18.0-16-generic.177025.crash -rw-r--r-- 1 kernoops whoopsie 0 Apr 2 08:36 linux-image-4.18.0-16-generic.184308.crash -rw-r--r-- 1 kernoops whoopsie 0 Apr 2 08:36 linux-image-4.18.0-16-generic.184489.crash -rw-r--r-- 1 kernoops whoopsie 0 Apr 2 08:36 linux-image-4.18.0-16-generic.184514.crash -rwxrwxrwx 1 root whoopsie 0 Apr 2 08:36 .lock* [ gary@Quasar | Tue 02 Apr 2019 10:11am ] ~ Both instances are from cores (#4 & #6) getting into a soft lockup.