I was playing with qemu and "-display gtk,gl=on -vga virtion". Suddenly a
kernel BUG was hit:
kernel BUG at ../drivers/gpu/drm/virtio/virtgpu_vq.c:130!
invalid opcode: 0000 [#1] PREEMPT SMP
Modules linked in: af_packet iscsi_ibft iscsi_boot_sysfs snd_hda_codec_generic
snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep virtio_gpu snd_pcm ttm
drm_kms_helper drm snd_timer ppdev fb_sys_fops syscopyarea sysfillrect snd
parport_pc joydev soundcore sysimgblt virtio_input acpi_cpufreq parport
virtio_net qemu_fw_cfg virtio_balloon i2c_piix4 pcspkr 8250_fintek tpm_tis tpm
button sr_mod cdrom virtio_scsi virtio_rng ata_generic uhci_hcd virtio_pci
ehci_hcd virtio_ring ata_piix usbcore floppy virtio serio_raw usb_common sg
CPU: 1 PID: 2253 Comm: X Not tainted 4.6.2-14.gb664f9a-default #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.9.1-0-gb3ef39f-prebuilt.qemu-project.org 04/01/2014
task: ffff880037754a00 ti: ffff88008eea8000 task.ti: ffff88008eea8000
RIP: 0010:[<ffffffffa02978db>]  [<ffffffffa02978db>]
virtio_gpu_get_vbuf+0x10b/0x120 [virtio_gpu]
RSP: 0018:ffff88008eeabc50  EFLAGS: 00010246
RAX: ffff880037754a00 RBX: ffff88008fe40000 RCX: ffff88008fe49608
RDX: ffff88008fe49608 RSI: ffff8800377552b0 RDI: ffff88008fe49618
RBP: ffff88008eeabc88 R08: ffff880037755260 R09: 0000000000000000
R10: ffff88008fe49630 R11: 000000114879e3c7 R12: 0000000000000020
R13: ffff88008fe49618 R14: 0000000000000018 R15: 0000000000000000
FS:  00007f7920063a00(0000) GS:ffff880094080000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557ba0bbef08 CR3: 000000008d1c9000 CR4: 00000000000006e0
Stack:
 0000000000000000 0000000000000000 ffff88008fe40000 0000000000000008
 ffff88008eeabd08 0000000000000001 ffff88008e1f9ac0 ffff88008eeabcc0
 ffffffffa0298f55 ffff88008eeabd10 ffff88008eeabde8 ffff88008e1f9ac0
Call Trace:
 [<ffffffffa0298f55>] virtio_gpu_cmd_submit+0x35/0xa0 [virtio_gpu]
 [<ffffffffa029b808>] virtio_gpu_execbuffer+0x388/0x590 [virtio_gpu]
 [<ffffffffa029ba1e>] virtio_gpu_execbuffer_ioctl+0xe/0x10 [virtio_gpu]
 [<ffffffffa01dfe82>] drm_ioctl+0x152/0x560 [drm]
 [<ffffffff8126c3a3>] do_vfs_ioctl+0x93/0x670
 [<ffffffff8126c9f9>] SyS_ioctl+0x79/0x90
 [<ffffffff81795740>] entry_SYSCALL_64_fastpath+0x23/0xc1
Code: 8b 45 c8 48 89 43 e8 49 89 c5 4d 85 ed 74 20 48 83 c4 10 48 89 d0 5b 41
5c 41 5d 41 5e 41 5f 5d c3 4e 8d 2c 20 4c 89 6b e8 eb df <0f> 0b 0f 0b 0f 0b 0f
1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00
RIP  [<ffffffffa02978db>] virtio_gpu_get_vbuf+0x10b/0x120 [virtio_gpu]
 RSP <ffff88008eeabc50>