I currently can't help much in debugging this problem, as I have limited time, and only one computer, and I'm a bit worried about corrupting the filesystem in the process. (I've been trying to set up user-mode linux with nilfs2 root fs, but so far haven't had success in bringing the UML setup up, unrelated to this problem.)
However, I believe Ryusuke Konishi has inspected this very issue and found the commit (f4bdb2697ccc9cecf1a9de86905c309ad901da4c) that triggers the bug. See the mail thread https://www.spinics.net/lists /linux-nilfs/msg04276.html -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1859979 Title: nilfs2 segctord kthread dies after which write to nilfs2 fs freezes the process writing Status in linux package in Ubuntu: Incomplete Bug description: With linux-image-5.3.0-26-lowlatency, segctord kthread encounters a "BUG: kernel NULL pointer dereference, address: 00000000000000a8" some half a minute from boot. Before that, one can log in to the system (/home is on a nilfs2 filesystem), but after the kernel BUG report, any write to a nilfs2 filesystem freezes the process trying to write, or any new login attempt freezes. This bug can be reproduced with every boot. With linux-image-5.3.0-24-lowlatency and earlier, this doesn't happen. Relevant excerpt from syslog: ... Jan 16 10:56:59 lillukka kernel: [ 0.000000] Linux version 5.3.0-26-lowlatency (buildd@lgw01-amd64-013) (gcc version 9.2.1 20191008 (Ubuntu 9.2.1-9ubuntu2)) #28-Ubuntu SMP PREEMPT Wed Dec 18 06:21:38 UTC 2019 (Ubuntu 5.3.0-26.28-lowlatency 5.3.13) ... Jan 16 10:57:13 lillukka kernel: [ 28.727753] BUG: kernel NULL pointer dereference, address: 00000000000000a8 Jan 16 10:57:13 lillukka kernel: [ 28.727852] #PF: supervisor read access in kernel mode Jan 16 10:57:13 lillukka kernel: [ 28.727914] #PF: error_code(0x0000) - not-present page Jan 16 10:57:13 lillukka kernel: [ 28.727974] PGD 0 P4D 0 Jan 16 10:57:13 lillukka kernel: [ 28.728012] Oops: 0000 [#1] PREEMPT SMP PTI Jan 16 10:57:13 lillukka kernel: [ 28.728067] CPU: 3 PID: 838 Comm: segctord Not tainted 5.3.0-26-lowlatency #28-Ubuntu Jan 16 10:57:13 lillukka kernel: [ 28.728156] Hardware name: Sony Corporation SVP1321C5E/VAIO, BIOS R0280V7 07/11/2013 Jan 16 10:57:13 lillukka kernel: [ 28.728257] RIP: 0010:percpu_counter_add_batch+0x13/0x80 Jan 16 10:57:13 lillukka kernel: [ 28.728334] Code: e0 41 5c 41 5d 41 5e 5d c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 55 48 89 e5 41 55 41 54 49 89 fc 53 65 ff 05 b5 5c ed 72 <48> 8b 47 20 48 63 ca 65 44 8b 28 49 63 dd 48 01 f3 48 39 d9 7e 0a Jan 16 10:57:13 lillukka kernel: [ 28.728536] RSP: 0018:ffffb582c02afcb0 EFLAGS: 00010082 Jan 16 10:57:13 lillukka kernel: [ 28.728598] RAX: 0000000000000002 RBX: 0000000000000000 RCX: 0000000000000001 Jan 16 10:57:13 lillukka kernel: [ 28.728679] RDX: 0000000000000018 RSI: 0000000000000001 RDI: 0000000000000088 Jan 16 10:57:13 lillukka kernel: [ 28.728760] RBP: ffffb582c02afcc8 R08: ffff8f519357ab40 R09: 0000000000000018 Jan 16 10:57:13 lillukka kernel: [ 28.728841] R10: 0000000000030140 R11: ffff8f5193609eea R12: 0000000000000088 Jan 16 10:57:13 lillukka kernel: [ 28.728920] R13: ffff8f518a3ee498 R14: ffff8f518a3ee608 R15: ffffe52b07e5a200 Jan 16 10:57:13 lillukka kernel: [ 28.729001] FS: 0000000000000000(0000) GS:ffff8f5197980000(0000) knlGS:0000000000000000 Jan 16 10:57:13 lillukka kernel: [ 28.729091] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Jan 16 10:57:13 lillukka kernel: [ 28.729157] CR2: 00000000000000a8 CR3: 000000008d60a002 CR4: 00000000001606e0 Jan 16 10:57:13 lillukka kernel: [ 28.729237] Call Trace: Jan 16 10:57:13 lillukka kernel: [ 28.729280] __test_set_page_writeback+0x2f1/0x310 Jan 16 10:57:13 lillukka kernel: [ 28.729362] nilfs_segctor_do_construct+0xd13/0x1260 [nilfs2] Jan 16 10:57:13 lillukka kernel: [ 28.729432] ? __switch_to_asm+0x40/0x70 Jan 16 10:57:13 lillukka kernel: [ 28.729496] nilfs_segctor_construct+0x1ff/0x2f0 [nilfs2] Jan 16 10:57:13 lillukka kernel: [ 28.729572] nilfs_segctor_thread+0x136/0x3a0 [nilfs2] Jan 16 10:57:13 lillukka kernel: [ 28.729640] kthread+0x104/0x140 Jan 16 10:57:13 lillukka kernel: [ 28.729690] ? nilfs_segctor_construct+0x2f0/0x2f0 [nilfs2] Jan 16 10:57:13 lillukka kernel: [ 28.729760] ? kthread_park+0x80/0x80 Jan 16 10:57:13 lillukka kernel: [ 28.729807] ret_from_fork+0x35/0x40 Jan 16 10:57:13 lillukka kernel: [ 28.729854] Modules linked in: ccm rfcomm aufs overlay cmac bnep nilfs2 snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_hda_codec_hdmi snd_hda_intel pn544_mei mei_phy pn544 snd_hda_codec hci snd_hda_core snd_hwdep intel_rapl_msr mei_hdcp nfc snd_pcm snd_seq_midi snd_seq_midi_event intel_rapl_common x86_pkg_temp_thermal intel_powerclamp snd_rawmidi coretemp iwlmvm mac80211 snd_seq btusb btrtl libarc4 btbcm uvcvideo btintel kvm videobuf2_vmalloc iwlwifi videobuf2_memops bluetooth snd_seq_device videobuf2_v4l2 videobuf2_common irqbypass joydev input_leds intel_cstate videodev ecdh_generic snd_timer intel_rapl_perf ecc serio_raw mc mei_me cfg80211 mei snd soundcore sony_laptop mac_hid intel_smartconnect sch_fq_codel cuse parport_pc ppdev lp parport ip_tables x_tables autofs4 btrfs xor zstd_compress raid6_pq libcrc32c dm_crypt dm_mirror dm_region_hash dm_log crct10dif_pclmul i915 crc32_pclmul ghash_clmulni_intel i2c_algo_bit drm_kms_helper syscopyarea aesni_intel sysfillrect Jan 16 10:57:13 lillukka kernel: [ 28.729928] sysimgblt aes_x86_64 crypto_simd cryptd glue_helper psmouse ahci fb_sys_fops libahci i2c_i801 drm lpc_ich video Jan 16 10:57:13 lillukka kernel: [ 28.730961] CR2: 00000000000000a8 Jan 16 10:57:13 lillukka kernel: [ 28.731005] ---[ end trace c5ef8752d8fe754e ]--- Jan 16 10:57:13 lillukka kernel: [ 28.731064] RIP: 0010:percpu_counter_add_batch+0x13/0x80 Jan 16 10:57:13 lillukka kernel: [ 28.731128] Code: e0 41 5c 41 5d 41 5e 5d c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 55 48 89 e5 41 55 41 54 49 89 fc 53 65 ff 05 b5 5c ed 72 <48> 8b 47 20 48 63 ca 65 44 8b 28 49 63 dd 48 01 f3 48 39 d9 7e 0a Jan 16 10:57:13 lillukka kernel: [ 28.731326] RSP: 0018:ffffb582c02afcb0 EFLAGS: 00010082 Jan 16 10:57:13 lillukka kernel: [ 28.731388] RAX: 0000000000000002 RBX: 0000000000000000 RCX: 0000000000000001 Jan 16 10:57:13 lillukka kernel: [ 28.731468] RDX: 0000000000000018 RSI: 0000000000000001 RDI: 0000000000000088 Jan 16 10:57:13 lillukka kernel: [ 28.731549] RBP: ffffb582c02afcc8 R08: ffff8f519357ab40 R09: 0000000000000018 Jan 16 10:57:13 lillukka kernel: [ 28.731629] R10: 0000000000030140 R11: ffff8f5193609eea R12: 0000000000000088 Jan 16 10:57:13 lillukka kernel: [ 28.731709] R13: ffff8f518a3ee498 R14: ffff8f518a3ee608 R15: ffffe52b07e5a200 Jan 16 10:57:13 lillukka kernel: [ 28.731790] FS: 0000000000000000(0000) GS:ffff8f5197980000(0000) knlGS:0000000000000000 Jan 16 10:57:13 lillukka kernel: [ 28.731881] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Jan 16 10:57:13 lillukka kernel: [ 28.731947] CR2: 00000000000000a8 CR3: 000000008d60a002 CR4: 00000000001606e0 Jan 16 10:57:13 lillukka kernel: [ 28.732084] note: segctord[838] exited with preempt_count 2 Jan 16 10:57:11 lillukka systemd-resolved[928]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature level UDP. Jan 16 10:57:19 lillukka systemd-resolved[928]: Using degraded feature set (UDP) for DNS server 192.168.1.1. Jan 16 10:57:22 lillukka systemd[1]: NetworkManager-dispatcher.service: Succeeded. Jan 16 10:57:29 lillukka systemd-timesyncd[929]: Synchronized to time server for the first time 91.189.91.157:123 (ntp.ubuntu.com). Jan 16 10:57:30 lillukka systemd[1]: systemd-hostnamed.service: Succeeded. Jan 16 11:01:16 lillukka wpa_supplicant[976]: wlp1s0: WPA: Group rekeying completed with 00:22:07:18:db:7e [GTK=TKIP] ... ProblemType: Bug DistroRelease: Ubuntu 19.10 Package: linux-image-5.3.0-26-lowlatency 5.3.0-26.28 ProcVersionSignature: Ubuntu 5.3.0-24.26-lowlatency 5.3.10 Uname: Linux 5.3.0-24-lowlatency x86_64 ApportVersion: 2.20.11-0ubuntu8.2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: jnykopp 4979 F.... pulseaudio /dev/snd/controlC0: jnykopp 4979 F.... pulseaudio CurrentDesktop: XFCE Date: Thu Jan 16 14:24:09 2020 MachineType: Sony Corporation SVP1321C5E ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.3.0-24-lowlatency root=/dev/mapper/hostname-root ro quiet splash RelatedPackageVersions: linux-restricted-modules-5.3.0-24-lowlatency N/A linux-backports-modules-5.3.0-24-lowlatency N/A linux-firmware 1.183.3 SourcePackage: linux UpgradeStatus: Upgraded to eoan on 2019-12-01 (45 days ago) dmi.bios.date: 07/11/2013 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: R0280V7 dmi.board.asset.tag: N/A dmi.board.name: VAIO dmi.board.vendor: Sony Corporation dmi.board.version: N/A dmi.chassis.asset.tag: N/A dmi.chassis.type: 10 dmi.chassis.vendor: Sony Corporation dmi.chassis.version: N/A dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrR0280V7:bd07/11/2013:svnSonyCorporation:pnSVP1321C5E:pvrC60C391V:rvnSonyCorporation:rnVAIO:rvrN/A:cvnSonyCorporation:ct10:cvrN/A: dmi.product.family: VAIO dmi.product.name: SVP1321C5E dmi.product.sku: 54641591 dmi.product.version: C60C391V dmi.sys.vendor: Sony Corporation To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1859979/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
