Issue still remains with the mainline kernel.  The contents of the kernel Oops message differs slightly, but still very similar:

[   27.532858] BUG: unable to handle kernel NULL pointer dereference at 00000000000003e8
[   27.532862] #PF error: [WRITE]
[   27.532865] PGD 0 P4D 0
[   27.532869] Oops: 0002 [#1] SMP NOPTI
[   27.532873] CPU: 3 PID: 82 Comm: kworker/3:1 Not tainted 5.1.0-050100rc3-generic #201904010618
[   27.532875] Hardware name: HP HP EliteBook 755 G5/83D5, BIOS Q81 Ver. 01.04.01 09/13/2018
[   27.532982] Workqueue: events dm_irq_work_func [amdgpu]
[   27.532989] RIP: 0010:queue_work_on+0x1b/0x40
[   27.532992] Code: 75 01 01 e8 f9 13 fe ff 0f 0b e9 b5 fc ff ff 0f 1f 44 00 00 55 48 89 e5 53 9c 58 0f 1f 44 00 00 48 89 c3 fa 66 0f 1f 44 00 00 <f0> 48 0f ba 2a 00 73 11 31 c9 48 89 df 57 9d 0f 1f 44 00 00 89 c8
[   27.532994] RSP: 0018:ffffc16bc1eebc88 EFLAGS: 00010002
[   27.532996] RAX: 0000000000000202 RBX: 0000000000000202 RCX: 0000000000000001
[   27.532998] RDX: 00000000000003e8 RSI: ffff9dde1e80d200 RDI: 0000000000002000
[   27.533000] RBP: ffffc16bc1eebc90 R08: 0000000000027080 R09: ffffffffb8210b0b
[   27.533002] R10: fffffc35106d5500 R11: ffff9dde1e86ca90 R12: ffff9dde0f2db646
[   27.533003] R13: ffff9dde1b4b9a80 R14: ffff9dde195eb000 R15: 0000000000000000
[   27.533006] FS:  0000000000000000(0000) GS:ffff9dde1ecc0000(0000) knlGS:0000000000000000
[   27.533008] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   27.533010] CR2: 00000000000003e8 CR3: 0000000411ca6000 CR4: 00000000003406a0
[   27.533011] Call Trace:
[   27.533026]  drm_dp_mst_handle_up_req+0x503/0x550 [drm_kms_helper]
[   27.533037]  drm_dp_mst_hpd_irq+0xbe/0xaa0 [drm_kms_helper]
[   27.533045]  ? drm_dp_mst_hpd_irq+0xbe/0xaa0 [drm_kms_helper]
[   27.533133]  handle_hpd_rx_irq+0x22c/0x2e0 [amdgpu]
[   27.533219]  ? handle_hpd_rx_irq+0x22c/0x2e0 [amdgpu]
[   27.533306]  dm_irq_work_func+0x53/0x70 [amdgpu]
[   27.533309]  process_one_work+0x20f/0x410
[   27.533312]  worker_thread+0x34/0x400
[   27.533315]  kthread+0x120/0x140
[   27.533318]  ? process_one_work+0x410/0x410
[   27.533320]  ? __kthread_parkme+0x70/0x70
[   27.533325]  ret_from_fork+0x22/0x40
[   27.533327] Modules linked in: cmac bnep btusb btrtl btbcm btintel bluetooth ecdh_generic bonding uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common videodev media nfc edac_mce_amd kvm_amd ccp kvm arc4 irqbypass nls_iso8859_1 crct10dif_pclmul crc32_pclmul snd_hda_codec_conexant ghash_clmulni_intel snd_hda_codec_generic snd_hda_codec_hdmi ledtrig_audio snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_pcm aesni_intel iwlmvm snd_seq_midi snd_seq_midi_event aes_x86_64 crypto_simd mac80211 cryptd snd_rawmidi glue_helper snd_seq iwlwifi snd_seq_device joydev snd_timer input_leds hp_wmi serio_raw sparse_keymap wmi_bmof snd k10temp cfg80211 soundcore ipmi_devintf ipmi_msghandler ucsi_acpi typec_ucsi typec hp_wireless mac_hid sch_fq_codel parport_pc ppdev lp parport ip_tables x_tables autofs4 amdgpu chash gpu_sched amd_iommu_v2 i2c_algo_bit ttm drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops nvme psmouse ahci drm libahci i2c_piix4 r8169 nvme_core realtek
[   27.533372]  wmi i2c_hid hid video
[   27.533378] CR2: 00000000000003e8
[   27.533380] ---[ end trace af80d2e3030b9f18 ]---