Comment 54 for bug 1796292

The newer kernel went about 16 runs and then popped this:

[ 2137.810559] md: md0: resync done.
[ 2296.795633] INFO: task python3:11639 blocked for more than 120 seconds.
[ 2296.800320] Tainted: P O 4.15.0-55-generic #60+lp1796292+1
[ 2296.805097] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 2296.810071] python3 D 0 11639 8301 0x00000000
[ 2296.810075] Call Trace:
[ 2296.810100] __schedule+0x291/0x8a0
[ 2296.810102] ? __switch_to_asm+0x34/0x70
[ 2296.810103] ? __switch_to_asm+0x40/0x70
[ 2296.810105] schedule+0x2c/0x80
[ 2296.810118] bch_bucket_alloc+0xe5/0x370 [bcache]
[ 2296.810128] ? wait_woken+0x80/0x80
[ 2296.810132] __bch_bucket_alloc_set+0x10d/0x160 [bcache]
[ 2296.810137] bch_bucket_alloc_set+0x4e/0x70 [bcache]
[ 2296.810143] __uuid_write+0x59/0x170 [bcache]
[ 2296.810148] ? __write_super+0x137/0x170 [bcache]
[ 2296.810153] bch_uuid_write+0x16/0x40 [bcache]
[ 2296.810159] __cached_dev_store+0x1e5/0x8b0 [bcache]
[ 2296.810160] ? __switch_to_asm+0x34/0x70
[ 2296.810161] ? __switch_to_asm+0x40/0x70
[ 2296.810163] ? __switch_to_asm+0x34/0x70
[ 2296.810167] bch_cached_dev_store+0x46/0x110 [bcache]
[ 2296.810181] sysfs_kf_write+0x3c/0x50
[ 2296.810182] kernfs_fop_write+0x125/0x1a0
[ 2296.810185] __vfs_write+0x1b/0x40
[ 2296.810187] vfs_write+0xb1/0x1a0
[ 2296.810189] SyS_write+0x55/0xc0
[ 2296.810193] do_syscall_64+0x73/0x130
[ 2296.810194] entry_SYSCALL_64_after_hwframe+0x3d/0xa2
[ 2296.810196] RIP: 0033:0x7f8e80077154
[ 2296.810197] RSP: 002b:00007fffc23855e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 2296.810199] RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 00007f8e80077154
[ 2296.810200] RDX: 0000000000000008 RSI: 0000000000d734b0 RDI: 0000000000000003
[ 2296.810201] RBP: 00007f8e805726c0 R08: 0000000000000000 R09: 0000000000000000
[ 2296.810202] R10: 0000000000000100 R11: 0000000000000246 R12: 0000000000000003
[ 2296.810203] R13: 0000000000000000 R14: 0000000000d734b0 R15: 0000000000aa4db0
[ 2417.627259] INFO: task python3:11639 blocked for more than 120 seconds.
[ 2417.632687] Tainted: P O 4.15.0-55-generic #60+lp1796292+1
[ 2417.638276] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.