Comment 0 for bug 1780628

I have a machine running linux-4.15.0-23-generic, and I can reliably trigger a kernel BUG under heavy write I/O using RAID 5.

$ cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4] [linear] [multipath] [raid0] [raid1] [raid10]
md0 : active raid5 sdd2[1] sda2[0] sdb2[2] sdc2[3]
      23440220160 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
      bitmap: 0/59 pages [0KB], 65536KB chunk

unused devices: <none>

[35679.932015] ------------[ cut here ]------------
[35679.932017] kernel BUG at /build/linux-uT8zSN/linux-4.15.0/drivers/md/raid5.c:1757!
[35679.932044] invalid opcode: 0000 [#1] SMP PTI
[35679.932054] Modules linked in: xfs nls_iso8859_1 ppdev intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic kvm_intel snd_hda_intel kvm snd_hda_codec snd_hda_core snd_hwdep snd_pcm irqbypass intel_cstate intel_rapl_perf snd_timer acpi_pad mei_me mei input_leds mac_hid snd shpchp wmi_bmof intel_pch_thermal soundcore parport_pc parport sch_fq_codel ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi ip_tables x_tables autofs4 btrfs zstd_compress raid10 raid1 raid0 multipath linear raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc i915 aesni_intel aes_x86_64 crypto_simd glue_helper
[35679.932199] cryptd i2c_algo_bit drm_kms_helper e1000e syscopyarea sysfillrect sysimgblt fb_sys_fops ptp ahci pps_core drm libahci wmi video
[35679.932229] CPU: 2 PID: 272 Comm: md0_raid5 Not tainted 4.15.0-23-generic #25-Ubuntu
[35679.932245] Hardware name: Gigabyte Technology Co., Ltd. H370M-D3H/H370M D3H-CF, BIOS F3 03/01/2018
[35679.932266] RIP: 0010:raid_run_ops+0xbcc/0x15f0 [raid456]
[35679.932277] RSP: 0018:ffffa95d0133fb30 EFLAGS: 00010006
[35679.932289] RAX: 0000000000000000 RBX: ffff96231cf67a34 RCX: 0000000000000000
[35679.932304] RDX: ffff96231d2cd7c0 RSI: ffff962303321380 RDI: ffff96231d2cd828
[35679.932318] RBP: ffffa95d0133fbe8 R08: 0000000000001000 R09: ffffa95d0133fac0
[35679.932333] R10: 0000000000001000 R11: ffff96231d2cd848 R12: ffff96231d2cda08
[35679.932347] R13: ffff96231d2cd828 R14: ffff96231d2cd7c0 R15: ffff962319bc8000
[35679.932362] FS: 0000000000000000(0000) GS:ffff96232e480000(0000) knlGS:0000000000000000
[35679.932379] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[35679.932391] CR2: 0000564929900bb8 CR3: 0000000041a0a003 CR4: 00000000003606e0
[35679.932405] Call Trace:
[35679.932415] handle_stripe+0x669/0x21c0 [raid456]
[35679.932428] handle_active_stripes.isra.62+0x3da/0x5a0 [raid456]
[35679.932442] raid5d+0x407/0x5f0 [raid456]
[35679.932454] md_thread+0x129/0x170
[35679.932463] ? handle_active_stripes.isra.62+0x5a0/0x5a0 [raid456]
[35679.932477] ? md_thread+0x129/0x170
[35679.932487] ? wait_woken+0x80/0x80
[35679.932497] kthread+0x121/0x140
[35679.932505] ? find_pers+0x70/0x70
[35679.932515] ? kthread_create_worker_on_cpu+0x70/0x70
[35679.932527] ret_from_fork+0x35/0x40
[35679.932536] Code: 48 63 d2 48 8d 04 d0 48 89 45 c8 0f 84 9a 09 00 00 48 8b 7d 98 44 89 f1 31 d2 4c 89 e6 e8 9d a9 e7 ff 48 89 45 98 e9 06 f6 ff ff <0f> 0b 0f 0b e9 89 f9 ff ff 8b 4d 90 89 fe e9 7e fd ff ff 4c 8b
[35679.932588] RIP: raid_run_ops+0xbcc/0x15f0 [raid456] RSP: ffffa95d0133fb30
[35679.932603] ---[ end trace 22e551ef3119d0b0 ]---

$ cat /proc/version_signature
Ubuntu 4.15.0-23.25-generic 4.15.18