Additional info:
reporter:       libreport-2.9.4
BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
IP: nouveau_mem_host+0x3e/0x1b0 [nouveau]
PGD 8000000104cfd067 P4D 8000000104cfd067 PUD 110fc7067 PMD 0 
Oops: 0000 [#1] SMP PTI
Modules linked in: fuse dm_crypt ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set nfnetlink ebtable_nat ebtable_broute bridge stp llc ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_raw ip6table_security iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_raw iptable_security ebtable_filter ebtables ip6table_filter ip6_tables sunrpc usblp intel_powerclamp coretemp kvm_intel snd_hda_codec_via snd_hda_codec_generic snd_hda_codec_hdmi kvm irqbypass snd_hda_intel iTCO_wdt iTCO_vendor_support intel_cstate intel_uncore i7core_edac snd_hda_codec snd_hda_core cdc_ether usbnet snd_hwdep joydev i2c_i801 snd_seq snd_seq_device snd_pcm shpchp asus_atk0110 snd_timer lpc_ich snd soundcore acpi_cpufreq libcrc32c
 uas usb_storage nouveau video mxm_wmi wmi i2c_algo_bit drm_kms_helper ttm crc32c_intel drm serio_raw ata_generic r8169 pata_acpi pata_via mii
CPU: 3 PID: 859 Comm: Xorg Not tainted 4.16.3-301.fc28.x86_64 #1
Hardware name: System manufacturer System Product Name/P7P55 LX, BIOS 1003    07/08/2010
RIP: 0010:nouveau_mem_host+0x3e/0x1b0 [nouveau]
RSP: 0018:ffffa59b41cef7f8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000005c2fd400
RDX: ffff8f4a99f9d380 RSI: ffff8f4a461c5300 RDI: ffffa59b41cef958
RBP: ffff8f4a461c5980 R08: 0000000000000000 R09: 0000000000000000
R10: ffffc6ff43108000 R11: 00000000000002a0 R12: ffffa59b41cef958
R13: ffff8f4a94b01000 R14: ffffa59b41cef958 R15: ffff8f4a461c5980
FS:  00007fc22ca7cac0(0000) GS:ffff8f4a9b2c0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000040 CR3: 0000000110d92000 CR4: 00000000000006e0
Call Trace:
 ? ttm_dma_populate+0x20c/0x390 [ttm]
 nv50_sgdma_bind+0x18/0x30 [nouveau]
 ttm_tt_bind+0x44/0x60 [ttm]
 ttm_bo_handle_move_mem+0x4cd/0x530 [ttm]
 ttm_bo_evict+0x140/0x1a0 [ttm]
 ? drm_rect_clip_scaled+0x71/0x160 [drm]
 ttm_mem_evict_first+0x193/0x200 [ttm]
 ttm_bo_mem_space+0x2de/0x4a0 [ttm]
 ttm_bo_validate+0xc7/0x130 [ttm]
 ? drm_rect_clip_scaled+0x126/0x160 [drm]
 ttm_bo_init_reserved+0x334/0x380 [ttm]
 ? ttm_bo_init+0x62/0xd0 [ttm]
 ? nouveau_bo_invalidate_caches+0x10/0x10 [nouveau]
 ? nouveau_bo_new+0x401/0x580 [nouveau]
 ? nouveau_bo_invalidate_caches+0x10/0x10 [nouveau]
 ? nouveau_gem_new+0x120/0x120 [nouveau]
 ? nouveau_gem_new+0x5d/0x120 [nouveau]
 ? nouveau_gem_ioctl_new+0x53/0xe0 [nouveau]
 ? drm_ioctl_kernel+0x5b/0xb0 [drm]
 ? drm_ioctl+0x1c0/0x380 [drm]
 ? nouveau_gem_new+0x120/0x120 [nouveau]
 ? nouveau_drm_ioctl+0x65/0xc0 [nouveau]
 ? do_vfs_ioctl+0xa4/0x610
 ? SyS_ioctl+0x74/0x80
 ? do_syscall_64+0x74/0x180
 ? entry_SYSCALL_64_after_hwframe+0x3d/0xa2
Code: 83 ec 28 4c 8b 3f 65 48 8b 04 25 28 00 00 00 48 89 44 24 20 31 c0 49 8b 1f 48 c7 44 24 08 00 00 00 00 48 c7 44 24 10 00 00 00 00 <48> 8b 7b 40 48 8d 83 f8 00 00 00 44 0f b6 6b 39 48 c7 44 24 18 
RIP: nouveau_mem_host+0x3e/0x1b0 [nouveau] RSP: ffffa59b41cef7f8
CR2: 0000000000000040