Kafs 6.16.0-rc2 BUG: kernel NULL pointer dereference

Thu Jun 19 09:30:52 PDT 2025

Dear all

Using kafs 6.16.0-rc2 I will get 
"BUG: kernel NULL pointer dereference, address"
I have no reproducer for this but I will hit this about 
once per day.

-Markus Suvanto

Full dmesg:
https://talvi.dynv6.net/nextcloud/index.php/s/FzRWFfkJ4C57GLH

[18709.773957] br0: port 2(enp6s0u1u4u1) entered forwarding state
[18709.774002] br0: topology change detected, propagating
[19904.460774] Callback UUID does not match fileserver UUID
[19914.317223] kAFS: Volume 2303380924 'common.portage' on server 0061c5ec-1b44-17a1-9303-110ba8c0aa77 is busy
[20588.779571] BUG: kernel NULL pointer dereference, address: 0000000000000008
[20588.779588] #PF: supervisor write access in kernel mode
[20588.779597] #PF: error_code(0x0002) - not-present page
[20588.779606] PGD 0 P4D 0 
[20588.779622] Oops: Oops: 0002 [#1] SMP PTI
[20588.779635] CPU: 1 UID: 0 PID: 17846 Comm: kworker/1:0 Not tainted 6.16.0-rc2 #2 VOLUNTARY 
[20588.779651] Hardware name: LENOVO 20HF0047MX/20HF0047MX, BIOS N1WET68W (1.47 ) 07/21/2022
[20588.779660] Workqueue: afs afs_fs_probe_dispatcher [kafs]
[20588.779743] RIP: 0010:afs_dispatch_fs_probe+0x17/0x60 [kafs]
[20588.779814] Code: 00 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 48 8d 46 40 48 89 fd 53 48 89 f3 48 89
df 48 8b 4e 40 48 8b 56 48 <48> 89 51 08 48 89 0a 48 89 46 40 48 89 46 48 be 04 00 00 00 e8 10
[20588.779825] RSP: 0018:ffffab5a8a8ebe10 EFLAGS: 00010246
[20588.779837] RAX: ffff8de10b7acc40 RBX: ffff8de10b7acc00 RCX: 0000000000000000
[20588.779845] RDX: 0000000000000000 RSI: ffff8de10b7acc00 RDI: ffff8de10b7acc00
[20588.779853] RBP: ffff8de084653c00 R08: ffff8de198112a40 R09: ffff8de08c9e14c0
[20588.779860] R10: fefefefefefefeff R11: ffff8de0a863cd40 R12: ffff8de084653d50
[20588.779867] R13: 3ffffffffffffffe R14: ffff8de084653d70 R15: 0000000000000001
[20588.779876] FS:  0000000000000000(0000) GS:ffff8de61b06e000(0000) knlGS:0000000000000000
[20588.779885] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[20588.779893] CR2: 0000000000000008 CR3: 000000038e92e002 CR4: 00000000003726f0
[20588.779901] Call Trace:
[20588.779910]  <TASK>
[20588.779919]  afs_fs_probe_dispatcher+0xd0/0x260 [kafs]
[20588.779992]  process_one_work+0x138/0x220
[20588.780011]  worker_thread+0x2ca/0x400
[20588.780027]  ? __pfx_worker_thread+0x10/0x10
[20588.780041]  kthread+0xce/0x1b0
[20588.780052]  ? __pfx_kthread+0x10/0x10
[20588.780061]  ? __pfx_kthread+0x10/0x10
[20588.780072]  ret_from_fork+0x6f/0xd0
[20588.780085]  ? __pfx_kthread+0x10/0x10
[20588.780095]  ret_from_fork_asm+0x1a/0x30
[20588.780112]  </TASK>
[20588.780117] Modules linked in: ccm snd_seq_dummy snd_hrtimer snd_seq snd_seq_device rfcomm af_packet uhid cmac
algif_hash algif_skcipher af_alg rmi_smbus rmi_core bridge stp llc kvmgt mdev vfio_iommu_type1 vfio coretemp
intel_rapl_msr bnep intel_rapl_common iommufd intel_uncore_frequency intel_uncore_frequency_co
mmon intel_pmc_core_pltdrv cachefiles intel_pmc_core sha3_generic jitterentropy_rng pmt_telemetry pmt_class drbg
ansi_cprng snd_soc_avs intel_pmc_ssram_telemetry intel_vsec snd_hda_codec_hdmi snd_soc_hda_codec intel_tcc_cooling
snd_hda_ext_core tpm_crb x86_pkg_temp_thermal intel_powerclamp snd_soc_core snd_hda_codec
_realtek snd_compress snd_hda_codec_generic cdc_ether ee1004 ac97_bus snd_hda_scodec_component snd_pcm_dmaengine
snd_ctl_led kvm_intel iwlmvm mei_hdcp usbnet mei_pxp mac80211 kvm snd_hda_intel uvcvideo snd_intel_dspcfg
videobuf2_vmalloc irqbypass libarc4 snd_hda_codec rapl uvc btusb videobuf2_memops intel_cstate iwl
wifi kafs btrtl tpm_tis intel_uncore videobuf2_v4l2 fcrypt nls_iso8859_1 snd_hda_core
[20588.780399]  thinkpad_acpi btintel efi_pstore pcbc btbcm nvram e1000e videodev think_lmi rxrpc nls_cp437 tpm_tis_core
snd_pcm platform_profile i2c_i801 ip6_udp_tunnel firmware_attributes_class i2c_mux btmtk intel_wmi_thunderbolt krb5 ptp
sparse_keymap pps_core wmi_bmof snd_timer bluetooth udp_tunnel cfg80211 snd 
tpm i2c_smbus r8152 videobuf2_common dns_resolver mei_me joydev tiny_power_button vfat mii fat rfkill netfs mc mei
intel_pch_thermal crc16 intel_xhci_usb_role_switch soundcore libaescfb thermal rtc_cmos ac ecdh_generic battery bfq
rng_core ecc acpi_pad evdev button mousedev input_leds sch_fq_codel loop fuse dm_mod c
onfigfs nfnetlink crc32c_cryptoapi hid_logitech_hidpp sd_mod hid_logitech_dj hid_generic usbmouse usbkbd usbhid uas
usb_storage scsi_mod scsi_common i915 cfbimgblt cfbfillrect cfbcopyarea drm_client_lib i2c_algo_bit fb_io_fops cec
drm_buddy iosf_mbi ttm intel_gtt psmouse agpgart serio_raw drm_display_helper atkbd dr
m_kms_helper libps2 vivaldi_fmap drm drm_panel_orientation_quirks nvme xhci_pci
[20588.780742]  polyval_clmulni ghash_clmulni_intel xhci_hcd fb sha512_ssse3 font usbcore aesni_intel gf128mul libaes
nvme_core usb_common hwmon ucsi_acpi typec_ucsi lcd roles ledtrig_backlight typec video thunderbolt i2c_core i8042 serio
wmi backlight btrfs blake2b_generic xor raid6_pq zstd_compress msr efivarfs dm
i_sysfs sha1_generic sha1_ssse3 ipv6 autofs4
[20588.780875] CR2: 0000000000000008
[20588.780884] ---[ end trace 0000000000000000 ]---
[20588.814189] pstore: backend (efi_pstore) writing error (-28)
[20588.814195] RIP: 0010:afs_dispatch_fs_probe+0x17/0x60 [kafs]
[20588.814217] Code: 00 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 48 8d 46 40 48 89 fd 53 48 89 f3 48 89
df 48 8b 4e 40 48 8b 56 48 <48> 89 51 08 48 89 0a 48 89 46 40 48 89 46 48 be 04 00 00 00 e8 10
[20588.814219] RSP: 0018:ffffab5a8a8ebe10 EFLAGS: 00010246
[20588.814223] RAX: ffff8de10b7acc40 RBX: ffff8de10b7acc00 RCX: 0000000000000000
[20588.814225] RDX: 0000000000000000 RSI: ffff8de10b7acc00 RDI: ffff8de10b7acc00
[20588.814227] RBP: ffff8de084653c00 R08: ffff8de198112a40 R09: ffff8de08c9e14c0
[20588.814228] R10: fefefefefefefeff R11: ffff8de0a863cd40 R12: ffff8de084653d50
[20588.814230] R13: 3ffffffffffffffe R14: ffff8de084653d70 R15: 0000000000000001
[20588.814232] FS:  0000000000000000(0000) GS:ffff8de61b06e000(0000) knlGS:0000000000000000
[20588.814234] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[20588.814236] CR2: 0000000000000008 CR3: 000000048d018005 CR4: 00000000003726f0
[20588.814238] note: kworker/1:0[17846] exited with irqs disabled