warning in cleanup_mnt #1033
Description
This seems to be happening when a systemd unit removes a snapshot (with bcachefs subvolume delete).
[root@hallewell:~]# uname -a
Linux hallewell 6.18.3 #1-NixOS SMP PREEMPT_DYNAMIC Fri Jan 2 11:57:31 UTC 2026 x86_64 GNU/Linux
[root@hallewell:~]# cat /sys/module/bcachefs/version
1.34.0
Raw message:
[42954.079304] ------------[ cut here ]------------
[42954.079307] WARNING: CPU: 0 PID: 403738 at fs/namespace.c:1309 cleanup_mnt+0x133/0x140
[42954.079313] Modules linked in: bluetooth ecdh_generic ecc msr xt_conntrack xt_MASQUERADE xt_tcpudp xt_mark nft_compat x_tables nft_chain_nat nf_nat tun overlay af_packet cfg80211 rfkill nf_log_syslog nft_log nft_ct nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nf_tables snd_hda_codec_intelhdmi snd_hda_codec_alc882 snd_hda_codec_realtek_lib snd_hda_codec_generic bcachefs(O) nfsd snd_hda_intel snd_sof_pci_intel_cnl snd_sof_intel_hda_generic auth_rpcgss soundwire_intel nfs_acl snd_sof_intel_hda_sdw_bpt lockd snd_sof_intel_hda_common grace nfs_localio snd_soc_hdac_hda snd_sof_intel_hda_mlink snd_sof_intel_hda snd_hda_codec_hdmi sunrpc soundwire_cadence snd_sof_pci snd_sof_xtensa_dsp sch_fq_codel snd_sof snd_sof_utils intel_rapl_msr snd_soc_acpi_intel_match snd_soc_acpi_intel_sdca_quirks soundwire_generic_allocation vfio_pci snd_soc_acpi vfio_pci_core soundwire_bus vfio_iommu_type1 intel_rapl_common vfio intel_uncore_frequency snd_soc_sdca intel_uncore_frequency_common iommufd
[42954.079353] crc8 snd_soc_avs intel_tcc_cooling snd_soc_hda_codec tls snd_hda_ext_core x86_pkg_temp_thermal intel_powerclamp snd_hda_codec coretemp loop kvm_intel snd_hda_core snd_intel_dspcfg snd_intel_sdw_acpi mei_hdcp mei_pxp snd_hwdep kvm iTCO_wdt irqbypass snd_soc_core intel_pmc_bxt ofpart ee1004 polyval_clmulni i2c_dev cmdlinepart ghash_clmulni_intel snd_compress aesni_intel rapl spi_nor atkbd ac97_bus libps2 snd_pcm_dmaengine libchacha nls_iso8859_1 serio xor intel_cstate mtd snd_pcm nls_cp437 intel_oc_wdt intel_pmc_core raid6_pq input_leds i2c_i801 vfat pmt_telemetry intel_uncore intel_wmi_thunderbolt mpt3sas wmi_bmof rtc_cmos snd_timer pmt_discovery libpoly1305 snd fat watchdog vivaldi_fmap spi_intel_pci mei_me led_class i2c_smbus evdev mousedev raid_class pmt_class soundcore spi_intel mxm_wmi i2c_mux scsi_transport_sas joydev i915 mei mac_hid intel_pmc_ssram_telemetry acpi_pad intel_vsec acpi_tad tiny_power_button uas edac_core amdgpu intel_gtt intel_pch_thermal button amdxcp drm_panel_backlight_quirks
[42954.079403] gpu_sched drm_buddy drm_exec drm_suballoc_helper drm_ttm_helper ttm drm_display_helper cec i2c_algo_bit fuse efi_pstore configfs nfnetlink zram 842_decompress 842_compress lz4hc_compress lz4_compress efivarfs dmi_sysfs autofs4 ext4 crc16 mbcache jbd2 sr_mod cdrom hid_generic sd_mod usbhid hid usb_storage ahci libahci libata nvme xhci_pci video e1000e nvme_core xhci_hcd scsi_mod nvme_keyring nvme_auth hkdf ptp wmi pps_core scsi_common dm_mod dax
[42954.079431] CPU: 0 UID: 0 PID: 403738 Comm: restic-backups- Tainted: G W O 6.18.3 #1-NixOS PREEMPT(voluntary)
[42954.079434] Tainted: [W]=WARN, [O]=OOT_MODULE
[42954.079435] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./Z390 Extreme4, BIOS P4.30 11/29/2019
[42954.079436] RIP: 0010:cleanup_mnt+0x133/0x140
[42954.079439] Code: 8f c7 87 44 01 00 00 00 00 00 00 e9 6f ff ff ff c7 87 44 01 00 00 00 00 00 00 eb de 48 89 ef e8 83 50 02 00 e9 f7 fe ff ff 90 <0f> 0b 90 e9 e0 fe ff ff 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90
[42954.079440] RSP: 0018:ffffcb0441f73e40 EFLAGS: 00010202
[42954.079442] RAX: 0000000000000001 RBX: ffff89c41e108dc0 RCX: ffff89d22f3ef000
[42954.079444] RDX: 0000000000000006 RSI: 0000000000000006 RDI: ffffffffbdb05a20
[42954.079445] RBP: ffff89c41e109200 R08: ffffffffbdb05a20 R09: 0000000000000000
[42954.079446] R10: 0000000000000001 R11: ffffffffbecae9c0 R12: ffff89c70fe60cb8
[42954.079447] R13: ffff89c3df78da01 R14: 0000000000000000 R15: 0000000000000000
[42954.079448] FS: 0000000000000000(0000) GS:ffff89d22f16f000(0000) knlGS:0000000000000000
[42954.079450] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[42954.079451] CR2: 00007f65a04ec4a0 CR3: 00000004bb224001 CR4: 00000000003726f0
[42954.079452] Call Trace:
[42954.079454] <TASK>
[42954.079457] task_work_run+0x5d/0x90
[42954.079461] do_exit+0x282/0xa70
[42954.079463] ? handle_mm_fault+0x1d9/0x2e0
[42954.079467] do_group_exit+0x2d/0xc0
[42954.079468] __x64_sys_exit_group+0x18/0x20
[42954.079470] x64_sys_call+0x14fa/0x1500
[42954.079473] do_syscall_64+0xb6/0x7e0
[42954.079476] ? exc_page_fault+0x6a/0x150
[42954.079479] entry_SYSCALL_64_after_hwframe+0x77/0x7f
[42954.079481] RIP: 0033:0x7f587bcec4b8
[42954.079492] Code: Unable to access opcode bytes at 0x7f587bcec48e.
[42954.079493] RSP: 002b:00007ffd3580c1d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
[42954.079495] RAX: ffffffffffffffda RBX: 00007f587bdfefa8 RCX: 00007f587bcec4b8
[42954.079496] RDX: 0000000000000000 RSI: ffffffffffffff88 RDI: 0000000000000000
[42954.079497] RBP: 00007ffd3580c230 R08: 0000000000000000 R09: 0000000000000000
[42954.079498] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
[42954.079499] R13: 0000000000000000 R14: 00007f587bdfd680 R15: 00007f587bdfefc0
[42954.079503] </TASK>
[42954.079503] ---[ end trace 0000000000000000 ]---
Ran through decode_stacktrace.sh:
[42954.079307] WARNING: CPU: 0 PID: 403738 at fs/namespace.c:1309 cleanup_mnt (/build/linux-6.18.3/build/../fs/namespace.c:1309 (discriminator 3))
[42954.079313] Modules linked in: bluetooth ecdh_generic ecc msr xt_conntrack xt_MASQUERADE xt_tcpudp xt_mark nft_compat x_tables nft_chain_nat nf_nat tun overlay af_packet cfg80211 rfkill nf_log_syslog nft_log nft_ct nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nf_tables snd_hda_codec_intelhdmi snd_hda_codec_alc882 snd_hda_codec_realtek_lib snd_hda_codec_generic bcachefs(O) nfsd snd_hda_intel snd_sof_pci_intel_cnl snd_sof_intel_hda_generic auth_rpcgss soundwire_intel nfs_acl snd_sof_intel_hda_sdw_bpt lockd snd_sof_intel_hda_common grace nfs_localio snd_soc_hdac_hda snd_sof_intel_hda_mlink snd_sof_intel_hda snd_hda_codec_hdmi sunrpc soundwire_cadence snd_sof_pci snd_sof_xtensa_dsp sch_fq_codel snd_sof snd_sof_utils intel_rapl_msr snd_soc_acpi_intel_match snd_soc_acpi_intel_sdca_quirks soundwire_generic_allocation vfio_pci snd_soc_acpi vfio_pci_core soundwire_bus vfio_iommu_type1 intel_rapl_common vfio intel_uncore_frequency snd_soc_sdca intel_uncore_frequency_common iommufd
[42954.079353] crc8 snd_soc_avs intel_tcc_cooling snd_soc_hda_codec tls snd_hda_ext_core x86_pkg_temp_thermal intel_powerclamp snd_hda_codec coretemp loop kvm_intel snd_hda_core snd_intel_dspcfg snd_intel_sdw_acpi mei_hdcp mei_pxp snd_hwdep kvm iTCO_wdt irqbypass snd_soc_core intel_pmc_bxt ofpart ee1004 polyval_clmulni i2c_dev cmdlinepart ghash_clmulni_intel snd_compress aesni_intel rapl spi_nor atkbd ac97_bus libps2 snd_pcm_dmaengine libchacha nls_iso8859_1 serio xor intel_cstate mtd snd_pcm nls_cp437 intel_oc_wdt intel_pmc_core raid6_pq input_leds i2c_i801 vfat pmt_telemetry intel_uncore intel_wmi_thunderbolt mpt3sas wmi_bmof rtc_cmos snd_timer pmt_discovery libpoly1305 snd fat watchdog vivaldi_fmap spi_intel_pci mei_me led_class i2c_smbus evdev mousedev raid_class pmt_class soundcore spi_intel mxm_wmi i2c_mux scsi_transport_sas joydev i915 mei mac_hid intel_pmc_ssram_telemetry acpi_pad intel_vsec acpi_tad tiny_power_button uas edac_core amdgpu intel_gtt intel_pch_thermal button amdxcp drm_panel_backlight_quirks
[42954.079403] gpu_sched drm_buddy drm_exec drm_suballoc_helper drm_ttm_helper ttm drm_display_helper cec i2c_algo_bit fuse efi_pstore configfs nfnetlink zram 842_decompress 842_compress lz4hc_compress lz4_compress efivarfs dmi_sysfs autofs4 ext4 crc16 mbcache jbd2 sr_mod cdrom hid_generic sd_mod usbhid hid usb_storage ahci libahci libata nvme xhci_pci video e1000e nvme_core xhci_hcd scsi_mod nvme_keyring nvme_auth hkdf ptp wmi pps_core scsi_common dm_mod dax
[42954.079431] CPU: 0 UID: 0 PID: 403738 Comm: restic-backups- Tainted: G W O 6.18.3 #1-NixOS PREEMPT(voluntary)
[42954.079434] Tainted: [W]=WARN, [O]=OOT_MODULE
[42954.079435] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./Z390 Extreme4, BIOS P4.30 11/29/2019
[42954.079436] RIP: 0010:cleanup_mnt (/build/linux-6.18.3/build/../fs/namespace.c:1309 (discriminator 3))
[42954.079439] Code: 8f c7 87 44 01 00 00 00 00 00 00 e9 6f ff ff ff c7 87 44 01 00 00 00 00 00 00 eb de 48 89 ef e8 83 50 02 00 e9 f7 fe ff ff 90 <0f> 0b 90 e9 e0 fe ff ff 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90
All code
========
0: 8f c7 pop %rdi
2: 87 44 01 00 xchg %eax,0x0(%rcx,%rax,1)
6: 00 00 add %al,(%rax)
8: 00 00 add %al,(%rax)
a: 00 e9 add %ch,%cl
c: 6f outsl %ds:(%rsi),(%dx)
d: ff (bad)
e: ff (bad)
f: ff c7 inc %edi
11: 87 44 01 00 xchg %eax,0x0(%rcx,%rax,1)
15: 00 00 add %al,(%rax)
17: 00 00 add %al,(%rax)
19: 00 eb add %ch,%bl
1b: de 48 89 fimuls -0x77(%rax)
1e: ef out %eax,(%dx)
1f: e8 83 50 02 00 call 0x250a7
24: e9 f7 fe ff ff jmp 0xffffffffffffff20
29: 90 nop
2a:* 0f 0b ud2 <-- trapping instruction
2c: 90 nop
2d: e9 e0 fe ff ff jmp 0xffffffffffffff12
32: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
37: 90 nop
38: 90 nop
39: 90 nop
3a: 90 nop
3b: 90 nop
3c: 90 nop
3d: 90 nop
3e: 90 nop
3f: 90 nop
Code starting with the faulting instruction
===========================================
0: 0f 0b ud2
2: 90 nop
3: e9 e0 fe ff ff jmp 0xfffffffffffffee8
8: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
d: 90 nop
e: 90 nop
f: 90 nop
10: 90 nop
11: 90 nop
12: 90 nop
13: 90 nop
14: 90 nop
15: 90 nop
[42954.079440] RSP: 0018:ffffcb0441f73e40 EFLAGS: 00010202
[42954.079442] RAX: 0000000000000001 RBX: ffff89c41e108dc0 RCX: ffff89d22f3ef000
[42954.079444] RDX: 0000000000000006 RSI: 0000000000000006 RDI: ffffffffbdb05a20
[42954.079445] RBP: ffff89c41e109200 R08: ffffffffbdb05a20 R09: 0000000000000000
[42954.079446] R10: 0000000000000001 R11: ffffffffbecae9c0 R12: ffff89c70fe60cb8
[42954.079447] R13: ffff89c3df78da01 R14: 0000000000000000 R15: 0000000000000000
[42954.079448] FS: 0000000000000000(0000) GS:ffff89d22f16f000(0000) knlGS:0000000000000000
[42954.079450] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[42954.079451] CR2: 00007f65a04ec4a0 CR3: 00000004bb224001 CR4: 00000000003726f0
[42954.079452] Call Trace:
[42954.079454] <TASK>
[42954.079457] task_work_run (/build/linux-6.18.3/build/../include/linux/sched.h:2076 /build/linux-6.18.3/build/../kernel/task_work.c:235)
[42954.079461] do_exit (/build/linux-6.18.3/build/../kernel/exit.c:967)
[42954.079463] ? handle_mm_fault (/build/linux-6.18.3/build/../mm/memory.c:6378 /build/linux-6.18.3/build/../mm/memory.c:6531)
[42954.079467] do_group_exit (/build/linux-6.18.3/build/../kernel/exit.c:1089)
[42954.079468] __x64_sys_exit_group (/build/linux-6.18.3/build/../kernel/exit.c:1118)
[42954.079470] x64_sys_call (/build/linux-6.18.3/build/./arch/x86/include/generated/asm/syscalls_64.h:61)
[42954.079473] do_syscall_64 (/build/linux-6.18.3/build/../arch/x86/entry/syscall_64.c:63 (discriminator 1) /build/linux-6.18.3/build/../arch/x86/entry/syscall_64.c:94 (discriminator 1))
[42954.079476] ? exc_page_fault (/build/linux-6.18.3/build/../arch/x86/include/asm/paravirt.h:666 /build/linux-6.18.3/build/../arch/x86/mm/fault.c:1484 /build/linux-6.18.3/build/../arch/x86/mm/fault.c:1532)
[42954.079479] entry_SYSCALL_64_after_hwframe (/build/linux-6.18.3/build/../arch/x86/entry/entry_64.S:130)
[42954.079481] RIP: 0033:0x7f587bcec4b8
[42954.079492] Code: Unable to access opcode bytes at 0x7f587bcec48e.
Code starting with the faulting instruction
===========================================
[42954.079493] RSP: 002b:00007ffd3580c1d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
[42954.079495] RAX: ffffffffffffffda RBX: 00007f587bdfefa8 RCX: 00007f587bcec4b8
[42954.079496] RDX: 0000000000000000 RSI: ffffffffffffff88 RDI: 0000000000000000
[42954.079497] RBP: 00007ffd3580c230 R08: 0000000000000000 R09: 0000000000000000
[42954.079498] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
[42954.079499] R13: 0000000000000000 R14: 00007f587bdfd680 R15: 00007f587bdfefc0
[42954.079503] </TASK>
[42954.079503] ---[ end trace 0000000000000000 ]---