[6.10-rc2] One-time kernel panic related to swap but Unraid doesn't have one

Hey,

some days ago I encountered weird system behaviour and could grab this out of `dmesg` before the system went unrensponsive.

The call trace looks like it has something to do with swap. But after reseraching this for a while it seems that Unraid doesn't use a swap partition or swap file by default. Since I never configured a swap on Unraid as well, I am very confused about this panic and don't know if it even has to do with the swap that I know from classic Linux.

No data seems to be lost on my disks or the boot stick. Parity check was successful.

I'm using btrfs with 2 NVMes in a cache, 1 parity HDD and 3 additional HDDs.

Is this some sort of case where cosmic radiation caused a bit flip (I'm not using ECC RAM) and I shouldn't worry about this or might there be a deeper root cause which I should investigate?

[1320874.636401] BUG: unable to handle page fault for address: fffff8efcea4a488
[1320874.636416] #PF: supervisor read access in kernel mode
[1320874.636421] #PF: error_code(0x0000) - not-present page
[1320874.636426] PGD 0 P4D 0
[1320874.636432] Oops: 0000 [#1] SMP PTI
[1320874.636438] CPU: 1 PID: 38 Comm: khugepaged Tainted: G        W         5.14.15-Unraid #1
[1320874.636445] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./Z77 Extreme4, BIOS P2.90 07/11/2013
[1320874.636451] RIP: 0010:_compound_head+0x0/0x11
[1320874.636462] Code: 89 e1 48 c7 c6 75 a2 eb 81 48 89 c2 e8 77 5e f6 ff 48 8d bb c8 10 00 00 5b 5d 41 5c 41 5d e9 f8 d3 f5 ff 5b 5d 41 5c 41 5d c3 <48> 8b 57 08 48 89 f8 f6 c2 01 74 04 48 8d 42 ff c3 e8 ea ff ff ff
[1320874.636472] RSP: 0018:ffffc90000173c78 EFLAGS: 00010246
[1320874.636477] RAX: ffffea0000000000 RBX: 00001507b9600000 RCX: 0000000000000000
[1320874.636483] RDX: 0000003bbf3a9292 RSI: ffff888107553ae0 RDI: fffff8efcea4a480
[1320874.636488] RBP: ffffea00041d54e8 R08: ffff88815cb0fe58 R09: 0000000000000000
[1320874.636492] R10: ffff88840f6a8288 R11: 0000000000000286 R12: fffff8efcea4a480
[1320874.636497] R13: 0000000000000000 R14: ffff888194e10cc0 R15: 7c00003bbf3a9292
[1320874.636503] FS:  0000000000000000(0000) GS:ffff88840f680000(0000) knlGS:0000000000000000
[1320874.636508] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1320874.636513] CR2: fffff8efcea4a488 CR3: 000000000200a006 CR4: 00000000001706e0
[1320874.636519] Call Trace:
[1320874.636525]  pfn_swap_entry_to_page+0x27/0x3c
[1320874.636533]  __migration_entry_wait+0x48/0x82
[1320874.636540]  do_swap_page+0x57/0x539
[1320874.636548]  __collapse_huge_page_swapin+0xc2/0x16b
[1320874.636557]  khugepaged+0xb0a/0x17c8
[1320874.636565]  ? collapse_pte_mapped_thp+0x284/0x284
[1320874.636571]  kthread+0xde/0xe3
[1320874.636577]  ? set_kthread_struct+0x32/0x32
[1320874.636583]  ret_from_fork+0x22/0x30
[1320874.636592] Modules linked in: vhost_net tun vhost vhost_iotlb tap kvm_intel kvm md_mod nf_tables xt_connmark xt_comment iptable_raw wireguard curve25519_x86_64 libcurve25519_generic libchacha20poly1305 chacha_x86_64 poly1305_x86_64 ip6_udp_tunnel udp_tunnel libblake2s blake2s_x86_64 libblake2s_generic libchacha xt_mark veth xt_CHECKSUM ipt_REJECT nf_reject_ipv4 xt_nat xt_tcpudp ip6table_mangle ip6table_nat iptable_mangle macvlan xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink xt_addrtype iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 br_netfilter xfs dm_crypt dm_mod dax ip6table_filter ip6_tables iptable_filter ip_tables x_tables bonding i915 x86_pkg_temp_thermal intel_powerclamp coretemp iosf_mbi crct10dif_pclmul i2c_algo_bit crc32_pclmul ttm crc32c_intel ghash_clmulni_intel mxm_wmi drm_kms_helper aesni_intel crypto_simd cryptd rapl drm intel_cstate intel_uncore intel_gtt agpgart i2c_i801 ahci tg3 i2c_smbus libahci nvme i2c_core syscopyarea nvme_core
[1320874.636690]  sysfillrect sysimgblt fb_sys_fops wmi video backlight button [last unloaded: md_mod]
[1320874.636735] CR2: fffff8efcea4a488
[1320874.636741] ---[ end trace 8ce14d1014ae0131 ]---
[1320874.636745] RIP: 0010:_compound_head+0x0/0x11
[1320874.636751] Code: 89 e1 48 c7 c6 75 a2 eb 81 48 89 c2 e8 77 5e f6 ff 48 8d bb c8 10 00 00 5b 5d 41 5c 41 5d e9 f8 d3 f5 ff 5b 5d 41 5c 41 5d c3 <48> 8b 57 08 48 89 f8 f6 c2 01 74 04 48 8d 42 ff c3 e8 ea ff ff ff
[1320874.636761] RSP: 0018:ffffc90000173c78 EFLAGS: 00010246
[1320874.636766] RAX: ffffea0000000000 RBX: 00001507b9600000 RCX: 0000000000000000
[1320874.636771] RDX: 0000003bbf3a9292 RSI: ffff888107553ae0 RDI: fffff8efcea4a480
[1320874.636775] RBP: ffffea00041d54e8 R08: ffff88815cb0fe58 R09: 0000000000000000
[1320874.636780] R10: ffff88840f6a8288 R11: 0000000000000286 R12: fffff8efcea4a480
[1320874.636785] R13: 0000000000000000 R14: ffff888194e10cc0 R15: 7c00003bbf3a9292
[1320874.636790] FS:  0000000000000000(0000) GS:ffff88840f680000(0000) knlGS:0000000000000000
[1320874.636795] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1320874.636800] CR2: fffff8efcea4a488 CR3: 000000000200a006 CR4: 00000000001706e0