Comment 7 for bug 1956101

Next test:
Same with boot options break=premount, but then only bpool imported:
(initramfs) modprobe zfs
(initramfs) zpool import -N bpool
(initramfs) zpool status
  pool: bpool
 state: ONLINE
  scan: scrub repaired 0B in 00:00:55 with 0 errors on Mon Sep 12 19:50:53 2022
config:

 NAME STATE READ WRITE CKSUM
 bpool ONLINE 0 0 0
  sda3 ONLINE 0 0 0

errors: No known data errors
[ 74.151238] BUG: kernel NULL pointer dereference, address: 00000000000006c8
[ 74.160142] #PF: supervisor write access in kernel mode
[ 74.167194] #PF: error_code(0x0002) - not-present page
[ 74.174128] PGD 0 P4D 0
[ 74.178425] Oops: 0002 [#1] SMP PTI
[ 74.183657] CPU: 21 PID: 1006 Comm: zpool Tainted: P O 5.15.0-40-generic #43-Ubuntu
[ 74.194395] Hardware name: Oracle Corporation SUN FIRE X4170 M3 /MOTHER BOARD ASSEMBL , BIOS 17160400 05/06/2020
[ 74.206842] RIP: 0010:mutex_lock+0x1e/0x40
[ 74.212748] Code: c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 54 49 89 fc e8 2d ed ff ff 31 c0 65 48 8b 14 25 c0 fb 01 00 <f0> 49 0f b1 14 24 75 06 4c 8b 65 f8 c9 c3 4c 89 e7 e8 ac ff ff ff
[ 74.235223] RSP: 0018:ffffaa064ece3b58 EFLAGS: 00010246
[ 74.242334] RAX: 0000000000000000 RBX: ffff9d3aa27ec000 RCX: 0000000000000000
[ 74.251373] RDX: ffff9d3a9e8e3180 RSI: 0000000000000000 RDI: 00000000000006c8
[ 74.260384] RBP: ffffaa064ece3b60 R08: ffff9d3a87d626c0 R09: ffff9d3a87d626c0
[ 74.269383] R10: ffff9d3ab9a5c800 R11: 0000000000000000 R12: 00000000000006c8
[ 74.278371] R13: 0000000000000000 R14: 00000000000006c8 R15: 00000000000006e8
[ 74.287355] FS: 00007f3c219a67c0(0000) GS:ffff9d519fd40000(0000) knlGS:0000000000000000
[ 74.297326] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 74.304922] CR2: 00000000000006c8 CR3: 00000001231e0003 CR4: 00000000000606e0
[ 74.313923] Call Trace:
[ 74.318223] <TASK>
[ 74.322154] rrw_enter_read_impl+0x29/0x110 [zfs]
[ 74.328957] rrw_enter_read+0x13/0x20 [zfs]
[ 74.335188] rrw_enter+0x1d/0x20 [zfs]
[ 74.340961] dsl_pool_config_enter+0x1d/0x20 [zfs]
[ 74.347762] spa_prop_get+0x98/0x3c0 [zfs]
[ 74.353891] ? spl_kmem_free_impl+0x25/0x30 [spl]
[ 74.360376] ? spl_kmem_free_impl+0x25/0x30 [spl]
[ 74.366838] ? kfree+0x1f3/0x250
[ 74.371805] ? __cond_resched+0x1a/0x50
[ 74.377357] ? avl_destroy_nodes+0x9e/0xf0 [zavl]
[ 74.383771] ? __cond_resched+0x1a/0x50
[ 74.389275] ? do_raw_spin_unlock+0x9/0x10 [zfs]
[ 74.395761] ? __raw_spin_unlock+0x9/0x10 [zfs]
[ 74.402143] ? spa_deactivate+0x22b/0x320 [zfs]
[ 74.408521] ? do_raw_spin_unlock+0x9/0x10 [zfs]
[ 74.414974] ? __raw_spin_unlock+0x9/0x10 [zfs]
[ 74.421340] ? spa_name_compare+0xe/0x30 [zfs]
[ 74.427646] ? avl_find+0x6b/0xd0 [zavl]
[ 74.433159] zfs_ioc_pool_get_props+0x79/0x140 [zfs]
[ 74.439986] zfsdev_ioctl_common+0x682/0x740 [zfs]
[ 74.446633] ? __check_object_size.part.0+0x4a/0x150
[ 74.453189] ? _copy_from_user+0x2e/0x60
[ 74.458693] zfsdev_ioctl+0x57/0xe0 [zfs]
[ 74.464552] __x64_sys_ioctl+0x91/0xc0
[ 74.469863] do_syscall_64+0x5c/0xc0
[ 74.474954] ? do_user_addr_fault+0x1e3/0x670
[ 74.480820] ? exit_to_user_mode_prepare+0x37/0xb0
[ 74.487091] ? irqentry_exit_to_user_mode+0x9/0x20
[ 74.493343] ? irqentry_exit+0x19/0x30
[ 74.498537] ? exc_page_fault+0x89/0x160
[ 74.503896] ? asm_exc_page_fault+0x8/0x30
[ 74.509437] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 74.515916] RIP: 0033:0x7f3c220fbaff
[ 74.520890] Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <41> 89 c0 3d 00 f0 ff ff 77 1f 48 8b 44 24 18 64 48 2b 04 25 28 00
[ 74.542483] RSP: 002b:00007fffe288b7a0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[ 74.551443] RAX: ffffffffffffffda RBX: 00005594463f23a0 RCX: 00007f3c220fbaff
[ 74.559955] RDX: 00007fffe288b800 RSI: 0000000000005a27 RDI: 0000000000000003
[ 74.568461] RBP: 00007fffe288ede0 R08: 0000000000000000 R09: 000055944642dd10
[ 74.576959] R10: 00007f3c221fb450 R11: 0000000000000246 R12: 00007fffe288b800
[ 74.585442] R13: 00005594463ea320 R14: 0000000000001000 R15: 00005594463f23a0
[ 74.593924] </TASK>
[ 74.597456] Modules linked in: zfs(PO) zunicode(PO) zzstd(O) zlua(O) zcommon(PO) znvpair(PO) zavl(PO) icp(PO) spl(O) cdc_ether usbnet mii hid_generic usbhid hid ast i2c_algo_bit drm_vram_helper drm_ttm_helper ttm drm_kms_helper syscopyarea qla2xxx sysfillrect nvme_fc uas sysimgblt nvme_fabrics fb_sys_fops ixgbe cec xfrm_algo rc_core usb_storage nvme_core ahci i2c_i801 dca crc32_pclmul drm i2c_smbus libahci lpc_ich megaraid_sas scsi_transport_fc mdio
[ 74.643123] CR2: 00000000000006c8
[ 74.648010] ---[ end trace 7ecc6f5dff7494cb ]---
[ 74.782147] RIP: 0010:mutex_lock+0x1e/0x40
[ 74.786884] Code: c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 54 49 89 fc e8 2d ed ff ff 31 c0 65 48 8b 14 25 c0 fb 01 00 <f0> 49 0f b1 14 24 75 06 4c 8b 65 f8 c9 c3 4c 89 e7 e8 ac ff ff ff
[ 74.806985] RSP: 0018:ffffaa064ece3b58 EFLAGS: 00010246
[ 74.812896] RAX: 0000000000000000 RBX: ffff9d3aa27ec000 RCX: 0000000000000000
[ 74.820723] RDX: ffff9d3a9e8e3180 RSI: 0000000000000000 RDI: 00000000000006c8
[ 74.828563] RBP: ffffaa064ece3b60 R08: ffff9d3a87d626c0 R09: ffff9d3a87d626c0
[ 74.836403] R10: ffff9d3ab9a5c800 R11: 0000000000000000 R12: 00000000000006c8
[ 74.844257] R13: 0000000000000000 R14: 00000000000006c8 R15: 00000000000006e8
[ 74.852101] FS: 00007f3c219a67c0(0000) GS:ffff9d519fd40000(0000) knlGS:0000000000000000
[ 74.860910] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 74.867384] CR2: 00000000000006c8 CR3: 00000001231e0003 CR4: 00000000000606e0
Killed
(initramfs)

So it seems to have nothing specific to do with the rpool.