cpu soft lockup

After upgrading from 14 LTS to 16 LTS the system started getting these hard lockups, where nothing works, can't get to it through ssh, or console.

in /var/log/kern.log:
Aug 7 21:47:26 XPS-8700 kernel: [26947.581772] NMI watchdog: BUG: soft lockup - CPU#2 stuck for 22s! [systemd-timesyn:2646]
Aug 7 21:47:26 XPS-8700 kernel: [26947.581774] Modules linked in: btrfs xor raid6_pq ufs qnx4 hfsplus hfs minix ntfs msdos jfs xfs libcrc32c vmnet(OE) vmw_vsock_vmci_transport vsock vmw_vmci vmmon(OE) bnep snd_hda_codec_hdmi dcdbas intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel arc4 kvm irqbypass crct10dif_pclmul crc32_pclmul ath9k ath9k_common aesni_intel ath9k_hw aes_x86_64 lrw gf128mul glue_helper ablk_helper ath cryptd mac80211 snd_hda_codec_realtek joydev snd_hda_codec_generic ath3k btusb serio_raw btrtl input_leds btbcm btintel bluetooth snd_hda_intel snd_hda_codec cfg80211 snd_hda_core snd_seq_midi snd_hwdep snd_seq_midi_event snd_rawmidi snd_pcm mei_me lpc_ich snd_seq mei snd_seq_device snd_timer snd soundcore shpchp mac_hid parport_pc ppdev lp parport autofs4 uas usb_storage hid_generic usbhid hid nouveau i915 mxm_wmi wmi ttm r8169 mii i2c_algo_bit drm_kms_helper syscopyarea sysfillrect psmouse sysimgblt ahci fb_sys_fops libahci drm video fjes

with some more debug dump info. What should I post to get help?

My system is stock DELL XPS 8700 with I7-4790. nothing special about this h/w.

I hope I won't have to revert back to 14 LTS, as I did have issues with kbd/mouse dead after booting. In 16 this problem is gone, but the lockups are even worse.

Any pointers wuld be appreciated.