Dear NILFSers I am perplexed because on upgrading my standard Ubuntu LTS kernel "4.15.0-88-generic" I keep getting null pointer dereferences as per attached kernel messages, and this did not happen with the previous version "4.15.0-72-generic". This seems to be happening with a specific filetree (I have 5 NILFS filetrees), but then I use mostly that one (the others are in large part archives). If it is that some corruption or uninitialized field has happened with that specific one I can easily recreate it.
[74917.285978] NILFS (dm-2): mounting unchecked fs [74917.523911] NILFS (dm-2): recovery complete [74917.525792] NILFS (dm-2): segctord starting. Construction interval = 10 seconds, CP frequency < 30 seconds [74919.917507] DROP_I last: IN=eth0 OUT= MAC=01:00:5e:00:00:01:10:13:31:a3:0d:ae:08:00 SRC=192.168.1.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0xC0 TTL= [75004.175846] BUG: unable to handle kernel NULL pointer dereference at 00000000000000a8 [75004.175864] IP: percpu_counter_add_batch+0xf/0x70 [75004.175868] PGD 0 P4D 0 [75004.175874] Oops: 0000 [#1] SMP NOPTI [75004.175878] Modules linked in: rfcomm dm_crypt nf_log_ipv6 xt_multiport nf_log_ipv4 nf_log_common xt_limit eeprom jc42 it87 hwmon_vid nf_nat_tft [75004.175923] xt_LOG ipt_ECN xt_DSCP ipt_CLUSTERIP iptable_raw iptable_nat nf_nat_ipv4 iptable_mangle arptable_filter arpt_mangle arp_tables sit [75004.175973] twofish_generic snd_seq_device snd_timer twofish_avx_x86_64 twofish_x86_64_3way snd twofish_x86_64 twofish_common soundcore i2c_pii [75004.176022] uas usb_storage amdkfd amd_iommu_v2 amdgpu chash i2c_algo_bit ttm drm_kms_helper syscopyarea hid_generic sysfillrect mxm_wmi sysimg [75004.176042] CPU: 6 PID: 15910 Comm: segctord Not tainted 4.15.0-88-generic #88~16.04.1-Ubuntu [75004.176046] Hardware name: To be filled by O.E.M. To be filled by O.E.M./M5A97 LE R2.0, BIOS 2501 04/09/2014 [75004.176063] RIP: 0010:percpu_counter_add_batch+0xf/0x70 [75004.176066] RSP: 0018:ffffb4d10e087cc0 EFLAGS: 00010006 [75004.176071] RAX: 0000000000000003 RBX: ffffed848f302f80 RCX: 000000000000001b [75004.176074] RDX: 0000000000000020 RSI: 0000000000000001 RDI: 0000000000000088 [75004.176078] RBP: ffffb4d10e087cd8 R08: 0000000000000000 R09: ffff9d0450dd0d90 [75004.176081] R10: 0000000000000000 R11: 0000000000000228 R12: 0000000000000088 [75004.176084] R13: 0000000000000001 R14: ffff9d0450cd5558 R15: ffff9d0450cd56d0 [75004.176088] FS: 0000000000000000(0000) GS:ffff9d047ed80000(0000) knlGS:0000000000000000 [75004.176092] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [75004.176095] CR2: 00000000000000a8 CR3: 0000000756614000 CR4: 00000000000406e0 [75004.176098] Call Trace: [75004.176109] __test_set_page_writeback+0x2f0/0x310 [75004.176133] nilfs_segctor_do_construct+0x152e/0x2070 [nilfs2] [75004.176151] nilfs_segctor_construct+0x1b0/0x310 [nilfs2] [75004.176167] ? nilfs_segctor_construct+0x1b0/0x310 [nilfs2] [75004.176183] nilfs_segctor_thread+0x108/0x380 [nilfs2] [75004.176189] kthread+0x105/0x140 [75004.176204] ? nilfs_segctor_construct+0x310/0x310 [nilfs2] [75004.176209] ? kthread_bind+0x40/0x40 [75004.176215] ret_from_fork+0x22/0x40 [75004.176219] Code: 38 e1 4e 00 48 89 d8 5b 41 5c 41 5d 5d c3 0f 1f 40 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 55 49 89 f5 41 54 49 89 fc [75004.176263] RIP: percpu_counter_add_batch+0xf/0x70 RSP: ffffb4d10e087cc0 [75004.176265] CR2: 00000000000000a8 [75004.176270] ---[ end trace 33744c64725742d2 ]---
