Hi! Starting with Linux 6.12-rc1 the automatic VM tests of NixOS don't boot anymore and fail like this: mounting nix-store on /nix/.ro-store... [ 1.604781] 9p: Installing v9fs 9p2000 file system support mounting tmpfs on /nix/.rw-store... mounting overlay on /nix/store... mounting shared on /tmp/shared... mounting xchg on /tmp/xchg... switch_root: can't execute '/nix/store/zv87gw0yxfsslq0mcc35a99k54da9a4z-nixos-system-machine-test/init': Exec format error [ 1.734997] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000100 [ 1.736002] CPU: 0 UID: 0 PID: 1 Comm: switch_root Not tainted 6.12.0-rc1 #1-NixOS [ 1.736965] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 1.738309] Call Trace: [ 1.738698] <TASK> [ 1.739034] panic+0x324/0x340 [ 1.739458] do_exit+0x92e/0xa90 [ 1.739919] ? count_memcg_events.constprop.0+0x1a/0x40 [ 1.740568] ? srso_return_thunk+0x5/0x5f [ 1.741095] ? handle_mm_fault+0xb0/0x2e0 [ 1.741709] do_group_exit+0x30/0x80 [ 1.742229] __x64_sys_exit_group+0x18/0x20 [ 1.742800] x64_sys_call+0x17f3/0x1800 [ 1.743326] do_syscall_64+0xb7/0x210 [ 1.743895] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 1.744530] RIP: 0033:0x7f8e1a7b9d1d [ 1.745061] Code: 45 31 c0 45 31 d2 45 31 db c3 0f 1f 00 f3 0f 1e fa 48 8b 35 e5 e0 10 00 ba e7 00 00 00 eb 07 66 0f 1f 44 00 00 f4 89 d0 0f 05 <48> 3d 00 f0 ff ff 76 f3 f7 d8 64 89 06 eb ec 0f 1f 40 00 f3 0f 1e [ 1.747263] RSP: 002b:00007ffcb56d63b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 1.748250] RAX: ffffffffffffffda RBX: 00007f8e1a8c9fa8 RCX: 00007f8e1a7b9d1d [ 1.749187] RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000001 [ 1.750050] RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 [ 1.750891] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 [ 1.751706] R13: 0000000000000001 R14: 00007f8e1a8c8680 R15: 00007f8e1a8c9fc0 [ 1.752583] </TASK> [ 1.753010] Kernel Offset: 0xb800000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) The failing script here is the initrd's /init when it tries to perform a switch_root to `/sysroot`: exec env -i $(type -P switch_root) "$targetRoot" "$stage2Init" Said "$stage2Init" file consistently gets a different hash when doing `sha256sum` on it in the initrd script, but looks & behaves correct on the host. I reproduced the test failures on 4 different build machines and two architectures (x86_64-linux, aarch64-linux) now. The "$stage2Init" script is a shell-script itself. When trying to start the interpreter from its shebang inside the initrd (via `$targetRoot/nix/store/...-bash-5.2p32/bin/bash`) and do the switch_root I get a different error: + exec env -i /nix/store/akm69s5sngxyvqrzys326dss9rsrvbpy-extra-utils/bin/switch_root /mnt-root /nix/store/k3pm4iv44y7x7p74kky6cwxiswmr6kpi-nixos-system-machine-test/init [ 1.912859] list_del corruption. prev->next should be ffffc5cf80be0248, but was ffffc5cf80bd9208. (prev=ffffc5cf80bb4d48) [ 1.914237] ------------[ cut here ]------------ [ 1.915059] kernel BUG at lib/list_debug.c:62! [ 1.915854] Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI [ 1.916739] CPU: 0 UID: 0 PID: 17 Comm: ksoftirqd/0 Not tainted 6.12.0-rc1 #1-NixOS [ 1.917837] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 1.919354] RIP: 0010:__list_del_entry_valid_or_report+0xb4/0xd0 [ 1.920180] Code: 0f 0b 48 89 fe 48 89 ca 48 c7 c7 38 52 41 9f e8 42 91 ac ff 90 0f 0b 48 89 fe 48 89 c2 48 c7 c7 70 52 41 9f e8 2d 91 ac ff 90 <0f> 0b 48 89 d1 48 c7 c7 c0 52 41 9f 48 89 f2 48 89 c6 e8 15 91 ac [ 1.922636] RSP: 0018:ffff96f800093c00 EFLAGS: 00010046 [ 1.923563] RAX: 000000000000006d RBX: 0000000000000001 RCX: 0000000000000000 [ 1.924692] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 1.925664] RBP: 0000000000000341 R08: 0000000000000000 R09: 0000000000000000 [ 1.926646] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8fbebd83dc90 [ 1.927584] R13: ffffc5cf80be0240 R14: ffff8fbebd83dc80 R15: 000000000002f809 [ 1.928533] FS: 0000000000000000(0000) GS:ffff8fbebd800000(0000) knlGS:0000000000000000 [ 1.929647] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.930431] CR2: 00007fed6f09b000 CR3: 0000000001e02000 CR4: 0000000000350ef0 [ 1.931333] Call Trace: [ 1.931727] <TASK> [ 1.932088] ? die+0x36/0x90 [ 1.932595] ? do_trap+0xed/0x110 [ 1.933047] ? __list_del_entry_valid_or_report+0xb4/0xd0 [ 1.933757] ? do_error_trap+0x6a/0xa0 [ 1.934390] ? __list_del_entry_valid_or_report+0xb4/0xd0 [ 1.935073] ? exc_invalid_op+0x51/0x80 [ 1.935627] ? __list_del_entry_valid_or_report+0xb4/0xd0 [ 1.936326] ? asm_exc_invalid_op+0x1a/0x20 [ 1.936904] ? __list_del_entry_valid_or_report+0xb4/0xd0 [ 1.937622] free_pcppages_bulk+0x130/0x280 [ 1.938151] free_unref_page_commit+0x21c/0x380 [ 1.938753] free_unref_page+0x472/0x4f0 [ 1.939343] __put_partials+0xee/0x130 [ 1.939921] ? rcu_do_batch+0x1f2/0x800 [ 1.940471] kmem_cache_free+0x2c3/0x370 [ 1.940990] rcu_do_batch+0x1f2/0x800 [ 1.941508] ? rcu_do_batch+0x180/0x800 [ 1.942031] rcu_core+0x182/0x340 [ 1.942500] handle_softirqs+0xe4/0x2f0 [ 1.943034] run_ksoftirqd+0x33/0x40 [ 1.943522] smpboot_thread_fn+0xdd/0x1d0 [ 1.944056] ? __pfx_smpboot_thread_fn+0x10/0x10 [ 1.944679] kthread+0xd0/0x100 [ 1.945126] ? __pfx_kthread+0x10/0x10 [ 1.945656] ret_from_fork+0x34/0x50 [ 1.946151] ? __pfx_kthread+0x10/0x10 [ 1.946680] ret_from_fork_asm+0x1a/0x30 [ 1.947269] </TASK> [ 1.947622] Modules linked in: overlay 9p ext4 crc32c_generic crc16 mbcache jbd2 hid_generic usbhid hid 9pnet_virtio 9pnet netfs sr_mod virtio_net cdrom virtio_blk net_failover atkbd failover libps2 vivaldi_fmap crc32c_intel ata_piix libata uhci_hcd scsi_mod ehci_hcd virtio_pci virtio_pci_legacy_dev virtio_pci_modern_dev scsi_common i8042 serio rtc_cmos dm_mod dax virtio_gpu virtio_dma_buf virtio_rng rng_core virtio_console virtio_balloon virtio virtio_ring [ 1.952291] ---[ end trace 0000000000000000 ]--- [ 1.952893] RIP: 0010:__list_del_entry_valid_or_report+0xb4/0xd0 [ 1.953678] Code: 0f 0b 48 89 fe 48 89 ca 48 c7 c7 38 52 41 9f e8 42 91 ac ff 90 0f 0b 48 89 fe 48 89 c2 48 c7 c7 70 52 41 9f e8 2d 91 ac ff 90 <0f> 0b 48 89 d1 48 c7 c7 c0 52 41 9f 48 89 f2 48 89 c6 e8 15 91 ac [ 1.955888] RSP: 0018:ffff96f800093c00 EFLAGS: 00010046 [ 1.956548] RAX: 000000000000006d RBX: 0000000000000001 RCX: 0000000000000000 [ 1.957436] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 1.958328] RBP: 0000000000000341 R08: 0000000000000000 R09: 0000000000000000 [ 1.959166] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8fbebd83dc90 [ 1.960044] R13: ffffc5cf80be0240 R14: ffff8fbebd83dc80 R15: 000000000002f809 [ 1.960905] FS: 0000000000000000(0000) GS:ffff8fbebd800000(0000) knlGS:0000000000000000 [ 1.961926] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.962693] CR2: 00007fed6f09b000 CR3: 0000000001e02000 CR4: 0000000000350ef0 [ 1.963548] Kernel panic - not syncing: Fatal exception in interrupt [ 1.964417] Kernel Offset: 0x1ce00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) On a subsequent run to verify this, it failed earlier while reading $targetRoot/.../bash like this: [ 1.871810] BUG: Bad page state in process cat pfn:2e74a [ 1.872481] page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x1e5 pfn:0x2e74a [ 1.873499] flags: 0xffffc000000000(node=0|zone=1|lastcpupid=0x1ffff) [ 1.874260] raw: 00ffffc000000000 dead000000000100 dead000000000122 0000000000000000 [ 1.875250] raw: 00000000000001e5 0000000000000000 00000001ffffffff 0000000000000000 [ 1.876295] page dumped because: nonzero _refcount [ 1.876910] Modules linked in: overlay 9p ext4 crc32c_generic crc16 mbcache jbd2 hid_generic usbhid hid 9pnet_virtio 9pnet netfs sr_mod virtio_net cdrom virtio_blk net_failover atkbd failover libps2 vivaldi_fmap crc32c_intel ata_piix libata scsi_mod uhci_hcd ehci_hcd virtio_pci virtio_pci_legacy_dev virtio_pci_modern_dev scsi_common i8042 serio rtc_cmos dm_mod dax virtio_gpu virtio_dma_buf virtio_rng rng_core virtio_console virtio_balloon virtio virtio_ring [ 1.881465] CPU: 0 UID: 0 PID: 315 Comm: cat Not tainted 6.12.0-rc1 #1-NixOS [ 1.882326] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 1.883684] Call Trace: [ 1.884103] <TASK> [ 1.884440] dump_stack_lvl+0x64/0x90 [ 1.884954] bad_page+0x70/0x110 [ 1.885468] __rmqueue_pcplist+0x209/0xd00 [ 1.886029] ? srso_return_thunk+0x5/0x5f [ 1.886572] ? pdu_read+0x36/0x50 [9pnet] [ 1.887177] get_page_from_freelist+0x2df/0x1910 [ 1.887788] ? srso_return_thunk+0x5/0x5f [ 1.888324] ? enqueue_entity+0xce/0x510 [ 1.888881] ? srso_return_thunk+0x5/0x5f [ 1.889415] ? pick_eevdf+0x76/0x1a0 [ 1.889970] ? update_curr+0x35/0x270 [ 1.890476] __alloc_pages_noprof+0x1a3/0x1150 [ 1.891158] ? srso_return_thunk+0x5/0x5f [ 1.891712] ? __mod_memcg_lruvec_state+0xa9/0x160 [ 1.892346] ? srso_return_thunk+0x5/0x5f [ 1.892919] ? __lruvec_stat_mod_folio+0x83/0xd0 [ 1.893521] alloc_pages_mpol_noprof+0x8f/0x1f0 [ 1.894148] folio_alloc_noprof+0x5b/0xb0 [ 1.894671] page_cache_ra_unbounded+0x11f/0x200 [ 1.895270] filemap_get_pages+0x538/0x6d0 [ 1.895813] ? srso_return_thunk+0x5/0x5f [ 1.896361] filemap_splice_read+0x136/0x320 [ 1.896948] backing_file_splice_read+0x52/0xa0 [ 1.897522] ovl_splice_read+0xd2/0xf0 [overlay] [ 1.898160] ? __pfx_ovl_file_accessed+0x10/0x10 [overlay] [ 1.898817] splice_direct_to_actor+0xb4/0x270 [ 1.899404] ? __pfx_direct_splice_actor+0x10/0x10 [ 1.900103] do_splice_direct+0x77/0xd0 [ 1.900627] ? __pfx_direct_file_splice_eof+0x10/0x10 [ 1.901308] do_sendfile+0x359/0x410 [ 1.901788] __x64_sys_sendfile64+0xb9/0xd0 [ 1.902370] do_syscall_64+0xb7/0x210 [ 1.902904] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 1.903604] RIP: 0033:0x7fa9f3a7289e [ 1.904214] Code: 75 0e 00 f7 d8 64 89 02 b8 ff ff ff ff 31 d2 31 c9 31 ff 45 31 db c3 0f 1f 44 00 00 f3 0f 1e fa 49 89 ca b8 28 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 12 31 d2 31 c9 31 f6 31 ff 45 31 d2 45 31 db [ 1.906436] RSP: 002b:00007ffe6a82bde8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 [ 1.907400] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fa9f3a7289e [ 1.908241] RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000001 [ 1.909184] RBP: 00007ffe6a82be50 R08: 0000000000000000 R09: 0000000000000000 [ 1.910212] R10: 0000000001000000 R11: 0000000000000246 R12: 0000000000000001 [ 1.911117] R13: 0000000001000000 R14: 0000000000000001 R15: 0000000000000000 [ 1.911998] </TASK> [ 1.912376] Disabling lock debugging due to kernel taint [ 1.913479] list_del corruption. next->prev should be ffffc80e40b9d948, but was ffffc80e40b9d0c8. (next=ffffc80e40b9c7c8) [ 1.914823] ------------[ cut here ]------------ [ 1.915408] kernel BUG at lib/list_debug.c:65! [ 1.916050] Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI [ 1.916785] CPU: 0 UID: 0 PID: 315 Comm: cat Tainted: G B 6.12.0-rc1 #1-NixOS [ 1.917877] Tainted: [B]=BAD_PAGE [ 1.918350] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 1.919996] RIP: 0010:__list_del_entry_valid_or_report+0xcc/0xd0 [ 1.920903] Code: 89 fe 48 89 c2 48 c7 c7 70 52 41 ba e8 2d 91 ac ff 90 0f 0b 48 89 d1 48 c7 c7 c0 52 41 ba 48 89 f2 48 89 c6 e8 15 91 ac ff 90 <0f> 0b 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f [ 1.923423] RSP: 0018:ffff9ed880187748 EFLAGS: 00010246 [ 1.924210] RAX: 000000000000006d RBX: ffff94db3d83dc80 RCX: 0000000000000000 [ 1.925147] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 1.926051] RBP: ffffc80e40b9d940 R08: 0000000000000000 R09: 0000000000000000 [ 1.926940] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 [ 1.927809] R13: ffff94db3d83dc80 R14: ffffc80e40b9d948 R15: ffff94db3ffd6180 [ 1.928695] FS: 00007fa9f396eb80(0000) GS:ffff94db3d800000(0000) knlGS:0000000000000000 [ 1.929728] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.930540] CR2: 00000000004d1829 CR3: 0000000001dd2000 CR4: 0000000000350ef0 [ 1.931444] Call Trace: [ 1.931916] <TASK> [ 1.932357] ? die+0x36/0x90 [ 1.932831] ? do_trap+0xed/0x110 [ 1.933385] ? __list_del_entry_valid_or_report+0xcc/0xd0 [ 1.934073] ? do_error_trap+0x6a/0xa0 [ 1.934583] ? __list_del_entry_valid_or_report+0xcc/0xd0 [ 1.935242] ? exc_invalid_op+0x51/0x80 [ 1.935781] ? __list_del_entry_valid_or_report+0xcc/0xd0 [ 1.936484] ? asm_exc_invalid_op+0x1a/0x20 [ 1.937174] ? __list_del_entry_valid_or_report+0xcc/0xd0 [ 1.937926] ? __list_del_entry_valid_or_report+0xcb/0xd0 [ 1.938685] __rmqueue_pcplist+0xa5/0xd00 [ 1.939292] ? srso_return_thunk+0x5/0x5f [ 1.940004] ? __mod_memcg_lruvec_state+0xa9/0x160 [ 1.940758] ? srso_return_thunk+0x5/0x5f [ 1.941417] ? update_load_avg+0x7e/0x7f0 [ 1.942133] ? srso_return_thunk+0x5/0x5f [ 1.942838] ? srso_return_thunk+0x5/0x5f [ 1.943508] get_page_from_freelist+0x2df/0x1910 [ 1.944143] ? srso_return_thunk+0x5/0x5f [ 1.944696] ? check_preempt_wakeup_fair+0x1ee/0x240 [ 1.945335] ? srso_return_thunk+0x5/0x5f [ 1.945905] __alloc_pages_noprof+0x1a3/0x1150 [ 1.946489] ? __blk_flush_plug+0xf5/0x150 [ 1.947105] ? srso_return_thunk+0x5/0x5f [ 1.947629] ? __dquot_alloc_space+0x2a8/0x3a0 [ 1.948404] ? srso_return_thunk+0x5/0x5f [ 1.949116] ? __mod_memcg_lruvec_state+0xa9/0x160 [ 1.949888] alloc_pages_mpol_noprof+0x8f/0x1f0 [ 1.950514] folio_alloc_mpol_noprof+0x14/0x40 [ 1.951153] shmem_alloc_folio+0xa7/0xd0 [ 1.951692] ? shmem_recalc_inode+0x20/0x90 [ 1.952272] shmem_alloc_and_add_folio+0x109/0x490 [ 1.952940] ? filemap_get_entry+0x10f/0x1a0 [ 1.953570] ? srso_return_thunk+0x5/0x5f [ 1.954185] shmem_get_folio_gfp+0x248/0x610 [ 1.954791] shmem_write_begin+0x64/0x110 [ 1.955484] generic_perform_write+0xdf/0x2a0 [ 1.956239] shmem_file_write_iter+0x8a/0x90 [ 1.956882] iter_file_splice_write+0x33f/0x580 [ 1.957577] direct_splice_actor+0x54/0x140 [ 1.958178] splice_direct_to_actor+0xec/0x270 [ 1.958813] ? __pfx_direct_splice_actor+0x10/0x10 [ 1.959442] do_splice_direct+0x77/0xd0 [ 1.960018] ? __pfx_direct_file_splice_eof+0x10/0x10 [ 1.960726] do_sendfile+0x359/0x410 [ 1.961248] __x64_sys_sendfile64+0xb9/0xd0 [ 1.961905] do_syscall_64+0xb7/0x210 [ 1.962467] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 1.963211] RIP: 0033:0x7fa9f3a7289e [ 1.963711] Code: 75 0e 00 f7 d8 64 89 02 b8 ff ff ff ff 31 d2 31 c9 31 ff 45 31 db c3 0f 1f 44 00 00 f3 0f 1e fa 49 89 ca b8 28 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 12 31 d2 31 c9 31 f6 31 ff 45 31 d2 45 31 db [ 1.965846] RSP: 002b:00007ffe6a82bde8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 [ 1.966788] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fa9f3a7289e [ 1.967644] RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000001 [ 1.968480] RBP: 00007ffe6a82be50 R08: 0000000000000000 R09: 0000000000000000 [ 1.969396] R10: 0000000001000000 R11: 0000000000000246 R12: 0000000000000001 [ 1.970315] R13: 0000000001000000 R14: 0000000000000001 R15: 0000000000000000 [ 1.971214] </TASK> [ 1.971572] Modules linked in: overlay 9p ext4 crc32c_generic crc16 mbcache jbd2 hid_generic usbhid hid 9pnet_virtio 9pnet netfs sr_mod virtio_net cdrom virtio_blk net_failover atkbd failover libps2 vivaldi_fmap crc32c_intel ata_piix libata scsi_mod uhci_hcd ehci_hcd virtio_pci virtio_pci_legacy_dev virtio_pci_modern_dev scsi_common i8042 serio rtc_cmos dm_mod dax virtio_gpu virtio_dma_buf virtio_rng rng_core virtio_console virtio_balloon virtio virtio_ring [ 1.976558] ---[ end trace 0000000000000000 ]--- [ 1.977219] RIP: 0010:__list_del_entry_valid_or_report+0xcc/0xd0 [ 1.978033] Code: 89 fe 48 89 c2 48 c7 c7 70 52 41 ba e8 2d 91 ac ff 90 0f 0b 48 89 d1 48 c7 c7 c0 52 41 ba 48 89 f2 48 89 c6 e8 15 91 ac ff 90 <0f> 0b 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f [ 1.980179] RSP: 0018:ffff9ed880187748 EFLAGS: 00010246 [ 1.980847] RAX: 000000000000006d RBX: ffff94db3d83dc80 RCX: 0000000000000000 [ 1.981705] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 1.982584] RBP: ffffc80e40b9d940 R08: 0000000000000000 R09: 0000000000000000 [ 1.983464] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 [ 1.984358] R13: ffff94db3d83dc80 R14: ffffc80e40b9d948 R15: ffff94db3ffd6180 [ 1.987765] FS: 00007fa9f396eb80(0000) GS:ffff94db3d800000(0000) knlGS:0000000000000000 [ 1.988805] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.989497] CR2: 00000000004d1829 CR3: 0000000001dd2000 CR4: 0000000000350ef0 [ 1.990418] note: cat[315] exited with preempt_count 2 I bisected it back to ee4cdf7ba857a894ad1650d6ab77669cbbfa329e which also seems to touch part of the 9p VFS code. Unfortunately the revert didn't apply cleanly on 6.12-rc1, so I couldn't meaningfully test whether a simple revert solves the problem. The VMs get the Nix store mounted via 9p. In the store are basically all build artifacts including the stage-2 init script of the system that is booted into in the VM test. The invocation basically looks like this: qemu-system-x86_64 -cpu max \ -name machine \ -m 1024 \ -smp 1 \ -device virtio-rng-pci \ -net nic,netdev=user.0,model=virtio -netdev user,id=user.0,"$QEMU_NET_OPTS" \ -virtfs local,path=/nix/store,security_model=none,mount_tag=nix-store \ -virtfs local,path="${SHARED_DIR:-$TMPDIR/xchg}",security_model=none,mount_tag=shared \ -virtfs local,path="$TMPDIR"/xchg,security_model=none,mount_tag=xchg \ -drive cache=writeback,file="$NIX_DISK_IMAGE",id=drive1,if=none,index=1,werror=report -device virtio-blk-pci,bootindex=1,drive=drive1,serial=root \ -device virtio-net-pci,netdev=vlan1,mac=52:54:00:12:01:01 \ -netdev vde,id=vlan1,sock="$QEMU_VDE_SOCKET_1" \ -device virtio-keyboard \ -usb \ -device usb-tablet,bus=usb-bus.0 \ -kernel ${NIXPKGS_QEMU_KERNEL_machine:-/nix/store/zv87gw0yxfsslq0mcc35a99k54da9a4z-nixos-system-machine-test/kernel} \ -initrd /nix/store/qqalw1iq1wbgq3ndx0cvqn3bfypn56w2-initrd-linux-6.12-rc1/initrd \ -append "$(cat /nix/store/zv87gw0yxfsslq0mcc35a99k54da9a4z-nixos-system-machine-test/kernel-params) init=/nix/store/zv87gw0yxfsslq0mcc35a99k54da9a4z-nixos-system-machine-test/init regInfo=/nix/store/5izvfal6xm2rk51v0r1h2cxcng33paby-closure-info/registration console=ttyS0 $QEMU_KERNEL_PARAMS" \ $QEMU_OPTS If you're using Nix, you can also reproduce this by running nix-build nixos/tests/kernel-generic.nix -A linux_testing on 5c19646b81db43dd7f4b6954f17d71a523009706 from https://github.com/nixos/nixpkgs. To me, this seems like a regression in rc1. Is there anything else I can do to help troubleshooting this? With best regards Maximilian