Apologies in advance, but I cannot git bisect this since machine was
running for 10 days on 6.6.8 before this happened.

Reporting in case it's useful (and not a hardware fail).

There is nothing interesting in journal ahead of the crash - previous
entry, 2 minutes prior from user space dhcp server.

 - Root, efi is on nvme
 - Spare root,efi is on sdg
 - md raid6 on sda-sd with lvmcache from one partition on nvme drive.
 - all filesystems are ext4 (other than efi).
 - 32 GB mem.


regards

gene

details attached which show:

Dec 30 07:00:36 s6 kernel:  <TASK>
Dec 30 07:00:36 s6 kernel:  ? __folio_mark_dirty+0x21c/0x2a0
Dec 30 07:00:36 s6 kernel:  ? __warn+0x81/0x130
Dec 30 07:00:36 s6 kernel:  ? __folio_mark_dirty+0x21c/0x2a0
Dec 30 07:00:36 s6 kernel:  ? report_bug+0x171/0x1a0
Dec 30 07:00:36 s6 kernel:  ? handle_bug+0x3c/0x80
Dec 30 07:00:36 s6 kernel:  ? exc_invalid_op+0x17/0x70
Dec 30 07:00:36 s6 kernel:  ? asm_exc_invalid_op+0x1a/0x20
Dec 30 07:00:36 s6 kernel:  ? __folio_mark_dirty+0x21c/0x2a0
Dec 30 07:00:36 s6 kernel:  block_dirty_folio+0x8a/0xb0
Dec 30 07:00:36 s6 kernel:  unmap_page_range+0xd17/0x1120
Dec 30 07:00:36 s6 kernel:  unmap_vmas+0xb5/0x190
Dec 30 07:00:36 s6 kernel:  exit_mmap+0xec/0x340
Dec 30 07:00:36 s6 kernel:  __mmput+0x3e/0x130
Dec 30 07:00:36 s6 kernel:  do_exit+0x31c/0xb20
Dec 30 07:00:36 s6 kernel:  do_group_exit+0x31/0x80
Dec 30 07:00:36 s6 kernel:  __x64_sys_exit_group+0x18/0x20
Dec 30 07:00:36 s6 kernel:  do_syscall_64+0x5d/0x90
Dec 30 07:00:36 s6 kernel:  ? count_memcg_events.constprop.0+0x1a/0x30
Dec 30 07:00:36 s6 kernel:  ? handle_mm_fault+0xa2/0x360
Dec 30 07:00:36 s6 kernel:  ? do_user_addr_fault+0x30f/0x660
Dec 30 07:00:36 s6 kernel:  ? exc_page_fault+0x7f/0x180
Dec 30 07:00:36 s6 kernel:  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
Dec 30 07:00:36 s6 kernel: RIP: 0033:0x7fb3c581ee2d
Dec 30 07:00:36 s6 kernel: Code: Unable to access opcode bytes at
0x7fb3c581ee03.
Dec 30 07:00:36 s6 kernel: RSP: 002b:00007fff620541e8 EFLAGS: 00000206
ORIG_RAX: 00000000000000e7
Dec 30 07:00:36 s6 kernel: RAX: ffffffffffffffda RBX: 00007fb3c591efa8
RCX: 00007fb3c581ee2d
Dec 30 07:00:36 s6 kernel: RDX: 00000000000000e7 RSI: ffffffffffffff88
RDI: 0000000000000000
Dec 30 07:00:36 s6 kernel: RBP: 0000000000000002 R08: 0000000000000000
R09: 00007fb3c5924920
Dec 30 07:00:36 s6 kernel: R10: 00005650f2e615f0 R11: 0000000000000206
R12: 0000000000000000
Dec 30 07:00:36 s6 kernel: R13: 0000000000000000 R14: 00007fb3c591d680
R15: 00007fb3c591efc0
Dec 30 07:00:36 s6 kernel:  </TASK>