I encountered this bug on a Debian Stretch system with an NFS 4 mount and cachefilesd 0.10.9. NFS 4 file systems are mounted like this from fstab: master.cluster.ai:/home /home nfs4 _netdev,fsc,noatime,vers=4.2,nodev,nosuid 0 0 master.cluster.ai:/cluster /srv/cluster nfs4 _netdev,fsc,noatime,vers=4.2,nodev,nosuid 0 0 cachefilesd.conf contains this: dir /var/cache/fscache tag mycache brun 10% bcull 7% bstop 3% frun 10% fcull 7% fstop 3% secctx system_u:system_r:cachefiles_kernel_t:s0 [2967555.161617] CacheFiles: [2967555.161652] CacheFiles: Error: Unexpected object collision [2967555.161712] CacheFiles: object: OBJ35e9f [2967555.161744] CacheFiles: objstate=LOOK_UP_OBJECT fl=8 wbusy=2 ev=0[0] [2967555.161790] CacheFiles: ops=0 inp=0 exc=0 [2967555.161821] CacheFiles: parent=ffff93a412926900 [2967555.161856] CacheFiles: cookie=ffff93aa080e53c0 [pr=ffff93a5327ce870 nd=ffff93acaa1be810 fl=27] [2967555.161918] CacheFiles: key=[32] '010006812fb038644d2346408da129441408b285fb15aa4600000000676141aa' [2967555.162076] CacheFiles: xobject: OBJ35e39 [2967555.162108] CacheFiles: xobjstate=WAIT_FOR_CMD fl=38 wbusy=1 ev=40[6d] [2967555.162156] CacheFiles: xops=0 inp=0 exc=0 [2967555.162188] CacheFiles: xparent=ffff93a412926900 [2967555.162225] CacheFiles: xcookie=ffff939ae8a6cbe0 [pr=ffff93a5327ce870 nd= (null) fl=18] [2967555.162325] ------------[ cut here ]------------ [2967555.162361] kernel BUG at /build/linux-zDY19G/linux-4.8.15/fs/cachefiles/namei.c:197! [2967555.162416] invalid opcode: 0000 [#1] SMP [2967555.162446] Modules linked in: bluetooth(E) rfkill(E) crc16(E) msr(E) rpcsec_gss_krb5(E) auth_rpcgss(E) nfsv4(E) dns_resolver(E) nfs(E) lockd(E) grace(E) sunrpc(E) 8021q(E) garp(E) mrp(E) stp(E) llc(E) cachefiles(E) fscache(E) xt_multiport(E) iptable_filter(E) dm_mod(E) binfmt_misc cpuid cpufreq_userspace cpufreq_powersave cpufreq_conservative intel_rapl sb_edac edac_core x86_pkg_temp_thermal coretemp mgag200 kvm_intel kvm ipmi_devintf irqbypass ttm drm_kms_helper drm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel iTCO_wdt i2c_algo_bit iTCO_vendor_support pcspkr evdev dcdbas sg ipmi_si ipmi_msghandler tpm_tis ioatdma wmi mei_me mei lpc_ich mfd_core tpm_tis_core tpm shpchp acpi_power_meter dca acpi_pad button psmouse ip_tables x_tables autofs4 xfs libcrc32c btrfs crc32c_generic xor raid6_pq hid_generic usbhid hid sd_mod crc32c_intel aesni_intel aes_x86_64 glue_helper lrw gf128mul ablk_helper cryptd ahci xhci_pci libahci xhci_hcd ehci_pci libata megaraid_sas ehci_hcd tg3 usbcor e ptp scsi_mod pps_core libphy usb_common fjes [2967555.163363] CPU: 29 PID: 206756 Comm: kworker/u578:0 Tainted: G E 4.8.0-2-amd64 #1 Debian 4.8.11-1 [2967555.163432] Hardware name: Dell Inc. PowerEdge R430/03XKDV, BIOS 1.2.6 06/08/2015 [2967555.163496] Workqueue: fscache_object fscache_object_work_func [fscache] [2967555.163546] task: ffff93aa2dec9000 task.stack: ffff93b18f1bc000 [2967555.163590] RIP: 0010:[<ffffffffc06d62a3>] [<ffffffffc06d62a3>] cachefiles_walk_to_object+0x7a3/0x800 [cachefiles] [2967555.163668] RSP: 0018:ffff93b18f1bfd18 EFLAGS: 00010286 [2967555.163708] RAX: 0000000000000000 RBX: ffff93ad450b9000 RCX: ffff93a86aec0600 [2967555.163776] RDX: 0000000000000005 RSI: ffff93a7eaec0600 RDI: 0000000000000286 [2967555.163828] RBP: ffff93b530706f00 R08: 0000000000000000 R09: 0000000000000000 [2967555.163882] R10: 000000000001e818 R11: 0000000000000001 R12: ffff939e213fbba8 [2967555.163935] R13: ffff939e213fba80 R14: ffff93a5320cd400 R15: ffff939eaa822240 [2967555.163988] FS: 0000000000000000(0000) GS:ffff93b53d580000(0000) knlGS:0000000000000000 [2967555.164048] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [2967555.164092] CR2: 00007f0a61ce1024 CR3: 00000018a020c000 CR4: 00000000001406e0 [2967555.164145] Stack: [2967555.164165] ffff93a5320cd520 ffff93ad450b9110 ffff93a7baecf000 ffff93aa2dec9000 [2967555.164230] ffff93b18f1bfd80 ffff93b18f1bfd98 ffffffffaceadda8 00000000342c372c [2967555.164297] ffff93b5301187e0 0000000000000246 0000000000000003 ffff93a3efcf5080 [2967555.164363] Call Trace: [2967555.164391] [<ffffffffaceadda8>] ? set_next_entity+0xa8/0x430 [2967555.164439] [<ffffffffc06d49a7>] ? cachefiles_lookup_object+0x47/0xe0 [cachefiles] [2967555.164501] [<ffffffffc03e6de0>] ? fscache_look_up_object+0xa0/0x1b0 [fscache] [2967555.164559] [<ffffffffc03e722a>] ? fscache_object_work_func+0x9a/0x1f0 [fscache] [2967555.164617] [<fffffffface94e00>] ? process_one_work+0x160/0x410 [2967555.164664] [<fffffffface950fd>] ? worker_thread+0x4d/0x480 [2967555.164708] [<fffffffface950b0>] ? process_one_work+0x410/0x410 [2967555.164755] [<fffffffface9aecd>] ? kthread+0xcd/0xf0 [2967555.164814] [<ffffffffad3efcaf>] ? ret_from_fork+0x1f/0x40 [2967555.164857] [<fffffffface9ae00>] ? kthread_create_on_node+0x190/0x190 [2967555.164903] Code: ec 0f 0b e8 40 5c 7a ec 48 c7 c7 91 95 6d c0 e8 e2 46 8a ec 48 c7 c7 80 a2 6d c0 e8 d6 46 8a ec 4c 89 ee 48 89 df e8 25 28 00 00 <0f> 0b 48 c7 c7 91 95 6d c0 e8 bd 46 8a ec 48 c7 c7 b8 a2 6d c0 [2967555.165258] RIP [<ffffffffc06d62a3>] cachefiles_walk_to_object+0x7a3/0x800 [cachefiles] [2967555.165321] RSP <ffff93b18f1bfd18> [2967555.180113] ---[ end trace 80e48067b39ab6d6 ]--- [2967555.237997] general protection fault: 0000 [#2] SMP [2967555.238051] Modules linked in: bluetooth(E) rfkill(E) crc16(E) msr(E) rpcsec_gss_krb5(E) auth_rpcgss(E) nfsv4(E) dns_resolver(E) nfs(E) lockd(E) grace(E) sunrpc(E) 8021q(E) garp(E) mrp(E) stp(E) llc(E) cachefiles(E) fscache(E) xt_multiport(E) iptable_filter(E) dm_mod(E) binfmt_misc cpuid cpufreq_userspace cpufreq_powersave cpufreq_conservative intel_rapl sb_edac edac_core x86_pkg_temp_thermal coretemp mgag200 kvm_intel kvm ipmi_devintf irqbypass ttm drm_kms_helper drm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel iTCO_wdt i2c_algo_bit iTCO_vendor_support pcspkr evdev dcdbas sg ipmi_si ipmi_msghandler tpm_tis ioatdma wmi mei_me mei lpc_ich mfd_core tpm_tis_core tpm shpchp acpi_power_meter dca acpi_pad button psmouse ip_tables x_tables autofs4 xfs libcrc32c btrfs crc32c_generic xor raid6_pq hid_generic usbhid hid sd_mod crc32c_intel aesni_intel aes_x86_64 glue_helper lrw gf128mul ablk_helper cryptd ahci xhci_pci libahci xhci_hcd ehci_pci libata megaraid_sas ehci_hcd tg3 usbcor e ptp scsi_mod pps_core libphy usb_common fjes [2967555.238927] CPU: 7 PID: 206756 Comm: kworker/u578:0 Tainted: G D E 4.8.0-2-amd64 #1 Debian 4.8.11-1 [2967555.242057] Hardware name: Dell Inc. PowerEdge R430/03XKDV, BIOS 1.2.6 06/08/2015 [2967555.245234] task: ffff93aa2dec9000 task.stack: ffff93b18f1bc000 [2967555.248355] RIP: 0010:[<ffffffffacec48d4>] [<ffffffffacec48d4>] native_queued_spin_lock_slowpath+0x104/0x190 [2967555.251582] RSP: 0018:ffff93b18f1bfe90 EFLAGS: 00010006 [2967555.254722] RAX: 000000000000234b RBX: 0000000000000282 RCX: ffff93b53d2d8cc0 [2967555.257977] RDX: 6f401c6375a7cadd RSI: 000000008d336c48 RDI: ffff93b18f1bff18 [2967555.261143] RBP: ffff93b18f1bff10 R08: 0000000000200000 R09: 0000000000000000 [2967555.264385] R10: 00000000ffffffff R11: 00000000000077ef R12: 0000000000000000 [2967555.267573] R13: ffffffffad5e44c6 R14: 0000000000000001 R15: ffff939eaa822240 [2967555.270821] FS: 0000000000000000(0000) GS:ffff93b53d2c0000(0000) knlGS:0000000000000000 [2967555.274001] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [2967555.277227] CR2: 0000000000000028 CR3: 0000001b4f406000 CR4: 00000000001406e0 [2967555.280393] Stack: [2967555.283582] ffffffffad3ef9f2 ffff93b18f1bff18 ffffffffacebd288 ffff93aa2dec9728 [2967555.286844] ffff93aa2dec9000 0000000000000000 fffffffface79680 ffff93aa2dec9000 [2967555.290123] 000000000000000b fffffffface7fbcb 35343438342c382c 000000006c8b5600 [2967555.293326] Call Trace: [2967555.296561] [<ffffffffad3ef9f2>] ? _raw_spin_lock_irqsave+0x32/0x39 [2967555.299748] [<ffffffffacebd288>] ? complete+0x18/0x40 [2967555.302937] [<fffffffface79680>] ? mm_release+0xb0/0x130 [2967555.305953] [<fffffffface7fbcb>] ? do_exit+0x14b/0xb30 [2967555.308945] [<ffffffffad3f1257>] ? rewind_stack_do_exit+0x17/0x20 [2967555.311780] [<fffffffface9ae00>] ? kthread_create_on_node+0x190/0x190 [2967555.314604] Code: c1 e0 10 45 31 c9 85 c0 74 44 48 89 c2 c1 e8 12 48 c1 ea 0c 83 e8 01 83 e2 30 48 98 48 81 c2 c0 8c 01 00 48 03 14 c5 c0 7c 91 ad <48> 89 0a 8b 41 08 85 c0 75 09 f3 90 8b 41 08 85 c0 74 f7 4c 8b [2967555.320446] RIP [<ffffffffacec48d4>] native_queued_spin_lock_slowpath+0x104/0x190 [2967555.323333] RSP <ffff93b18f1bfe90> [2967555.326195] ---[ end trace 80e48067b39ab6d7 ]--- [2967555.389315] Fixing recursive fault but reboot is needed! [2967555.389413] BUG: unable to handle kernel paging request at ffffffffffffffd8 [2967555.389436] IP: [<fffffffface9b53c>] kthread_data+0xc/0x20 [2967555.389438] PGD 1b4f409067 PUD 1b4f40b067 PMD 0 [2967555.389445] Oops: 0000 [#3] SMP [2967555.389531] Modules linked in: bluetooth(E) rfkill(E) crc16(E) msr(E) rpcsec_gss_krb5(E) auth_rpcgss(E) nfsv4(E) dns_resolver(E) nfs(E) lockd(E) grace(E) sunrpc(E) 8021q(E) garp(E) mrp(E) stp(E) llc(E) cachefiles(E) fscache(E) xt_multiport(E) iptable_filter(E) dm_mod(E) binfmt_misc cpuid cpufreq_userspace cpufreq_powersave cpufreq_conservative intel_rapl sb_edac edac_core x86_pkg_temp_thermal coretemp mgag200 kvm_intel kvm ipmi_devintf irqbypass ttm drm_kms_helper drm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel iTCO_wdt i2c_algo_bit iTCO_vendor_support pcspkr evdev dcdbas sg ipmi_si ipmi_msghandler tpm_tis ioatdma wmi mei_me mei lpc_ich mfd_core tpm_tis_core tpm shpchp acpi_power_meter dca acpi_pad button psmouse ip_tables x_tables autofs4 xfs libcrc32c btrfs crc32c_generic xor raid6_pq hid_generic usbhid hid sd_mod crc32c_intel aesni_intel aes_x86_64 glue_helper lrw gf128mul ablk_helper cryptd ahci xhci_pci libahci xhci_hcd ehci_pci libata megaraid_sas ehci_hcd tg3 usbcor e ptp scsi_mod pps_core libphy usb_common fjes [2967555.389558] CPU: 7 PID: 206756 Comm: kworker/u578:0 Tainted: G D E 4.8.0-2-amd64 #1 Debian 4.8.11-1 [2967555.389559] Hardware name: Dell Inc. PowerEdge R430/03XKDV, BIOS 1.2.6 06/08/2015 [2967555.389599] task: ffff93aa2dec9000 task.stack: ffff93b18f1bc000 [2967555.389612] RIP: 0010:[<fffffffface9b53c>] [<fffffffface9b53c>] kthread_data+0xc/0x20 [2967555.389613] RSP: 0018:ffff93b18f1bfe70 EFLAGS: 00010002 [2967555.389614] RAX: 0000000000000000 RBX: ffff93b53d2d8180 RCX: 0000000000000007 [2967555.389615] RDX: ffff93a53d406000 RSI: ffff93aa2dec9080 RDI: ffff93aa2dec9000 [2967555.389615] RBP: ffff93aa2dec9000 R08: ffff93aa2dec90a8 R09: 0000000000000001 [2967555.389616] R10: 0000000000000010 R11: ffff93aa2dec9080 R12: 0000000000018180 [2967555.389618] R13: 0000000000000000 R14: ffff93aa2dec95d0 R15: ffff93b53d2d8180 [2967555.389622] FS: 0000000000000000(0000) GS:ffff93b53d2c0000(0000) knlGS:0000000000000000 [2967555.389626] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [2967555.389627] CR2: 0000000000000028 CR3: 0000001b4f406000 CR4: 00000000001406e0 [2967555.389630] Stack: [2967555.389635] fffffffface9600a ffffffffad3eb423 ffff93b18f1bfee0 ffff93b18f1bfe98 [2967555.389640] 000000008d336c48 ffff93b18f1c0000 000000000000000b ffff93b18f1bfde8 [2967555.389645] ffffffffad5e44c6 0000000000000001 ffff939eaa822240 ffffffffad3eb6d1 [2967555.389645] Call Trace: [2967555.389648] [<fffffffface9600a>] ? wq_worker_sleeping+0xa/0x80 [2967555.389656] [<ffffffffad3eb423>] ? __schedule+0x4e3/0x760 [2967555.389664] [<ffffffffad3eb6d1>] ? schedule+0x31/0x80 [2967555.389670] [<fffffffface80397>] ? do_exit+0x917/0xb30 [2967555.389684] [<ffffffffad3f1257>] ? rewind_stack_do_exit+0x17/0x20 [2967555.389689] [<fffffffface9ae00>] ? kthread_create_on_node+0x190/0x190 [2967555.389711] Code: 00 00 48 c7 c7 08 96 5e ad e8 61 0d fe ff e9 ad fe ff ff 66 90 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 8b 87 70 05 00 00 <48> 8b 40 d8 c3 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f [2967555.389714] RIP [<fffffffface9b53c>] kthread_data+0xc/0x20 [2967555.389715] RSP <ffff93b18f1bfe70> [2967555.389716] CR2: ffffffffffffffd8 [2967555.389718] ---[ end trace 80e48067b39ab6d8 ]--- [2967555.451116] Fixing recursive fault but reboot is needed!
Created attachment 254839 [details] dmesg
Same trace in Ubuntu Xenial on a Google Cloud image, but this time with CIFS. https://bugs.launchpad.net/ubuntu/+source/linux-meta-hwe/+bug/1727861 I cannot get fscache to work at all. It looks fairly broken.
And Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=751933 Is the fault in cachefilesd?
Does this need to be e-mailed somewhere?
This is fixed somewhere between kernel 4.13 and 4.15. Vague, I know, but it's a starting point. Longterm support kernels may still be affected but testing would take me an age. If I get time I'll test further.