Recent tests with the most recent 5.15 kernel (5.15.0-25-generic) do display the same problem, though the symptom is different.
Booting w/o the swiotlb=262144 leads to the boot sequence stopping after these messages :
[ 1.376749] i2c i2c-0: Memory type 0x07 not supported yet, not instantiating SPD
[ 1.379840] cryptd: max_cpu_qlen set to 1000
[ 1.381359] scsi host1: ahci
[ 1.384854] AVX2 version of gcm_enc/dec engaged.
[ 1.385579] AES CTR mode by8 optimization enabled
[ 1.386280] scsi host2: ahci
[ 1.387162] scsi host3: ahci
[ 1.387659] scsi host4: ahci
[ 1.388141] scsi host5: ahci
[ 1.388675] scsi host6: ahci
[ 1.389091] ata1: SATA max UDMA/133 abar m4096@0x91000000 port 0x91000100 irq 36
[ 1.389937] ata2: SATA max UDMA/133 abar m4096@0x91000000 port 0x91000180 irq 36
[ 1.390787] ata3: SATA max UDMA/133 abar m4096@0x91000000 port 0x91000200 irq 36
[ 1.391599] ata4: SATA max UDMA/133 abar m4096@0x91000000 port 0x91000280 irq 36
[ 1.392417] ata5: SATA max UDMA/133 abar m4096@0x91000000 port 0x91000300 irq 36
[ 1.393251] ata6: SATA max UDMA/133 abar m4096@0x91000000 port 0x91000380 irq 36
[ 1.707933] ata3: SATA link down (SStatus 0 SControl 300)
[ 1.709684] ata4: SATA link down (SStatus 0 SControl 300)
[ 1.711379] ata5: SATA link down (SStatus 0 SControl 300)
[ 1.712945] ata2: SATA link down (SStatus 0 SControl 300)
[ 1.714405] ata1: SATA link down (SStatus 0 SControl 300)
[ 1.715926] ata6: SATA link down (SStatus 0 SControl 300)
[ 3.352937] pcieport 0000:00:1e.0: pciehp: Slot(0): No device found
[ 3.356935] pcieport 0000:00:1e.2: pciehp: Slot(2): No device found
[ 3.368942] pcieport 0000:00:1e.1: pciehp: Slot(1): No device found
[ 3.368958] pcieport 0000:00:1e.3: pciehp: Slot(3): No device found
[ 3.384970] pcieport 0000:00:1e.4: pciehp: Slot(4): No device found
[ 3.384991] pcieport 0000:00:1e.6: pciehp: Slot(6): No device found
[ 3.396926] pcieport 0000:00:1e.5: pciehp: Slot(5): No device found
[ 3.396957] pcieport 0000:00:1e.7: pciehp: Slot(7): No device found
And after a period of time we start seeing :
[ 242.880954] INFO: task kworker/u16:0:8 blocked for more than 120 seconds.
[ 242.882063] Not tainted 5.15.0-25-generic #25-Ubuntu
[ 242.882895] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 242.884165] task:kworker/u16:0 state:D stack: 0 pid: 8 ppid: 2 flags:0x00004000
[ 242.885520] Workqueue: events_unbound async_run_entry_fn
[ 242.886383] Call Trace:
[ 242.886783]
[ 242.887133] __schedule+0x23d/0x590
[ 242.887716] schedule+0x4e/0xb0
[ 242.888221] async_synchronize_cookie_domain+0xcc/0x110
[ 242.889077] ? wait_woken+0x70/0x70
[ 242.889637] async_synchronize_cookie+0x15/0x20
[ 242.890355] async_port_probe+0x4e/0x80
[ 242.890996] async_run_entry_fn+0x33/0x120
[ 242.891677] process_one_work+0x22b/0x3d0
[ 242.892344] worker_thread+0x53/0x410
[ 242.892955] ? process_one_work+0x3d0/0x3d0
[ 242.893653] kthread+0x12a/0x150
[ 242.894189] ? set_kthread_struct+0x50/0x50
[ 242.894835] ret_from_fork+0x22/0x30
[ 242.895393]
[ 242.895780] INFO: task kworker/u16:1:128 blocked for more than 120 seconds.
[ 242.896855] Not tainted 5.15.0-25-generic #25-Ubuntu
[ 242.897752] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 242.899028] task:kworker/u16:1 state:D stack: 0 pid: 128 ppid: 2 flags:0x00004000
[ 242.900346] Workqueue: events_unbound async_run_entry_fn
[ 242.901208] Call Trace:
[ 242.901633]
[ 242.901965] __schedule+0x23d/0x590
[ 242.902507] schedule+0x4e/0xb0
[ 242.903004] async_synchronize_cookie_domain+0xcc/0x110
[ 242.903837] ? wait_woken+0x70/0x70
[ 242.904414] async_synchronize_cookie+0x15/0x20
[ 242.905178] async_port_probe+0x4e/0x80
[ 242.905826] async_run_entry_fn+0x33/0x120
[ 242.906502] process_one_work+0x22b/0x3d0
[ 242.907173] worker_thread+0x53/0x410
[ 242.907777] ? process_one_work+0x3d0/0x3d0
[ 242.908442] kthread+0x12a/0x150
[ 242.908959] ? set_kthread_struct+0x50/0x50
[ 242.909576] ret_from_fork+0x22/0x30
[ 242.910120]