Короче, забиваю диск рандомом. По ошибке указал большой размер буфера, и теперь в логах появляется это:
[ 4302.025672] INFO: task pool:4638 blocked for more than 120 seconds.
[ 4302.025680] Tainted: P O 4.20.3 #1
[ 4302.025683] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 4302.025687] pool D 0 4638 1 0x00000000
[ 4302.025691] Call Trace:
[ 4302.025703] ? __schedule+0x3f5/0x880
[ 4302.025708] ? __flush_work+0x57/0x1d0
[ 4302.025712] schedule+0x32/0x80
[ 4302.025716] schedule_preempt_disabled+0xa/0x10
[ 4302.025719] __mutex_lock.isra.7+0x296/0x4d0
[ 4302.025726] ? __blkdev_get+0x149/0x4c0
[ 4302.025729] __blkdev_get+0x149/0x4c0
[ 4302.025734] ? bd_acquire+0xd0/0xd0
[ 4302.025737] blkdev_get+0x122/0x310
[ 4302.025741] ? inode_permission+0x29/0x130
[ 4302.025745] ? bd_acquire+0xd0/0xd0
[ 4302.025749] do_dentry_open+0x1de/0x340
[ 4302.025753] path_openat+0x782/0x1400
[ 4302.025759] do_filp_open+0x99/0x110
[ 4302.025763] ? _cond_resched+0x16/0x40
[ 4302.025766] ? _cond_resched+0x16/0x40
[ 4302.025769] ? __check_object_size+0x161/0x1a0
[ 4302.025774] ? do_sys_open+0x12e/0x210
[ 4302.025778] do_sys_open+0x12e/0x210
[ 4302.025782] do_syscall_64+0x55/0x100
[ 4302.025787] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 4302.025793] RIP: 0033:0x7fba08d5083d
[ 4302.025801] Code: Bad RIP value.
[ 4302.025803] RSP: 002b:00007fb9f6ffcb40 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
[ 4302.025806] RAX: ffffffffffffffda RBX: 000055870f907e70 RCX: 00007fba08d5083d
[ 4302.025808] RDX: 000055870f8edf60 RSI: 0000000000000800 RDI: 000055870f8edf60
[ 4302.025810] RBP: 00007fb9f8002810 R08: 000055870f8c6508 R09: 000055870f8cb568
[ 4302.025812] R10: aaaaaaaaaaaaaaab R11: 0000000000000293 R12: 00007fb9f6ffccd8
[ 4302.025813] R13: 00007fb9f6ffcc00 R14: 0000000000000000 R15: 00007fb9f8002810
[ 7630.523689] AVX2 instructions are not detected.
dd if=/dev/urandom|pv|dd of=/dev/sdb bs=192M