I missed the first three lines of the syslog snippet containing the BUG event, inlined here:
Oct 31 16:27:48 gonzo kernel: BUG: kernel NULL pointer dereference, address: 0000000000000028 Oct 31 16:27:48 gonzo kernel: #PF: supervisor write access in kernel mode Oct 31 16:27:48 gonzo kernel: #PF: error_code(0x0002) - not-present page Oct 31 16:27:49 gonzo kernel: PGD 8000000121c24067 P4D 8000000121c24067 PUD 1079bf067 PMD 0 Oct 31 16:27:49 gonzo kernel: Oops: 0002 [#1] SMP PTI Oct 31 16:27:49 gonzo kernel: CPU: 9 PID: 296 Comm: kswapd0 Tainted: G I 5.10.0-1-amd64 #1 Debian 5.10.4-1 Oct 31 16:27:49 gonzo kernel: Hardware name: System manufacturer System Product Name/ROG STRIX X299-E GAMING, BIOS 1503 08/03/2018 Oct 31 16:27:49 gonzo kernel: RIP: 0010:dentry_unlink_inode+0x51/0x100 Oct 31 16:27:49 gonzo kernel: Code: a9 00 00 08 00 74 08 65 48 ff 05 8a 45 75 52 48 8b 85 b8 00 00 00 48 85 c0 74 29 48 8b 95 b0 00 00 00 48 89 10 48 85 d2 74 04 <4> Oct 31 16:27:49 gonzo kernel: RSP: 0018:ffffb59d00a13b58 EFLAGS: 00010202 Oct 31 16:27:49 gonzo kernel: RAX: ffff9e2fbb8db9f8 RBX: ffff9e335a601740 RCX: 0000000000000000 Oct 31 16:27:49 gonzo kernel: RDX: 0000000000000020 RSI: ffff9e3466229350 RDI: ffff9e34662292c0 Oct 31 16:27:49 gonzo kernel: RBP: ffff9e34662292c0 R08: ffff9e34662282d0 R09: ffff9e2706d3e260 Oct 31 16:27:49 gonzo kernel: R10: 0000000000000000 R11: 0000000000000000 R12: ffff9e2fbb8db8c0 Oct 31 16:27:49 gonzo kernel: R13: ffff9e3466229318 R14: ffff9e2760c01870 R15: 0000000000000000 Oct 31 16:27:49 gonzo kernel: FS: 0000000000000000(0000) GS:ffff9e365fa40000(0000) knlGS:0000000000000000 Oct 31 16:27:49 gonzo kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Oct 31 16:27:49 gonzo kernel: CR2: 0000000000000028 CR3: 0000000107aac004 CR4: 00000000003706e0 Oct 31 16:27:49 gonzo kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 Oct 31 16:27:49 gonzo kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Oct 31 16:27:49 gonzo kernel: Call Trace: Oct 31 16:27:49 gonzo kernel: __dentry_kill+0xe4/0x180 Oct 31 16:27:49 gonzo kernel: shrink_dentry_list+0x4e/0xc0 Oct 31 16:27:49 gonzo kernel: prune_dcache_sb+0x54/0x80 Oct 31 16:27:49 gonzo kernel: super_cache_scan+0x12c/0x1e0 Oct 31 16:27:49 gonzo kernel: do_shrink_slab+0x145/0x240 Oct 31 16:27:49 gonzo kernel: shrink_slab+0x188/0x2a0 Oct 31 16:27:49 gonzo kernel: shrink_node+0x2c0/0x6e0 Oct 31 16:27:49 gonzo kernel: balance_pgdat+0x2e5/0x600 Oct 31 16:27:49 gonzo kernel: kswapd+0x1f6/0x380 Oct 31 16:27:49 gonzo kernel: ? add_wait_queue_exclusive+0x70/0x70 Oct 31 16:27:49 gonzo kernel: ? balance_pgdat+0x600/0x600 Oct 31 16:27:49 gonzo kernel: kthread+0x11b/0x140 Oct 31 16:27:49 gonzo kernel: ? __kthread_bind_mask+0x60/0x60 Oct 31 16:27:49 gonzo kernel: ret_from_fork+0x22/0x30 Oct 31 16:27:49 gonzo kernel: Modules linked in: xt_MASQUERADE xt_mark nft_compat nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_counter nf_tab> Oct 31 16:27:49 gonzo kernel: mei_me sg watchdog mei ioatdma dca evdev drm fuse configfs efivarfs ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 raid10 raid456> Oct 31 16:27:49 gonzo kernel: CR2: 0000000000000028 Oct 31 16:27:49 gonzo kernel: ---[ end trace 3c3f518d326d4df8 ]--- Oct 31 16:27:49 gonzo kernel: RIP: 0010:dentry_unlink_inode+0x51/0x100 Oct 31 16:27:49 gonzo kernel: Code: a9 00 00 08 00 74 08 65 48 ff 05 8a 45 75 52 48 8b 85 b8 00 00 00 48 85 c0 74 29 48 8b 95 b0 00 00 00 48 89 10 48 85 d2 74 04 <4> Oct 31 16:27:49 gonzo kernel: RSP: 0018:ffffb59d00a13b58 EFLAGS: 00010202 Oct 31 16:27:49 gonzo kernel: RAX: ffff9e2fbb8db9f8 RBX: ffff9e335a601740 RCX: 0000000000000000 Oct 31 16:27:49 gonzo kernel: RDX: 0000000000000020 RSI: ffff9e3466229350 RDI: ffff9e34662292c0 Oct 31 16:27:49 gonzo kernel: RBP: ffff9e34662292c0 R08: ffff9e34662282d0 R09: ffff9e2706d3e260 Oct 31 16:27:49 gonzo kernel: R10: 0000000000000000 R11: 0000000000000000 R12: ffff9e2fbb8db8c0 Oct 31 16:27:49 gonzo kernel: R13: ffff9e3466229318 R14: ffff9e2760c01870 R15: 0000000000000000 Oct 31 16:27:49 gonzo kernel: FS: 0000000000000000(0000) GS:ffff9e365fa40000(0000) knlGS:0000000000000000 Oct 31 16:27:49 gonzo kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Oct 31 16:27:49 gonzo kernel: CR2: 0000000000000028 CR3: 0000000107aac004 CR4: 00000000003706e0 Oct 31 16:27:49 gonzo kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 Oct 31 16:27:49 gonzo kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400