~ # dd if=/dev/random of=/dev/disk/by-partlabel/cache bs=1 count=1
1+0 records in
1+0 records out
1 bytes (1B) copied, 0.003342 seconds, 299B/s
~ # dd if=/dev/random of=/dev/disk/by-partlabel/cache bs=256 count=1
1+0 records in
1+0 records out
256 bytes (256B) copied, 0.002937 seconds, 85.1KB/s
~ # dd if=/dev/random of=/dev/disk/by-partlabel/cache bs=1024 count=1
1+0 records in
1+0 records out
1024 bytes (1.0KB) copied, 0.011899 seconds, 84.0KB/s
~ # dd if=/dev/random of=/dev/disk/by-partlabel/cache bs=1024 count=10
10+0 records in
10+0 records out
10240 bytes (10.0KB) copied, 0.008015 seconds, 1.2MB/s
~ # dd if=/dev/random of=/dev/disk/by-partlabel/cache bs=1M count=10
^C^C
^C
^C
^C
[  243.791662] INFO: task dd:784 blocked for more than 122 seconds.
[  243.791705]       Not tainted 6.13.0 #9
[  243.791722] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  243.791739] task:dd              state:D stack:0     pid:784   tgid:784   ppid:190    flags:0x00000000
[  243.791780] Call trace:
[  243.791802]  __schedule from schedule+0x3c/0x64
[  243.791865]  schedule from mmc_blk_rw_wait+0xc4/0x108
[  243.791922]  mmc_blk_rw_wait from mmc_blk_mq_issue_rq+0x6b8/0x75c
[  243.791969]  mmc_blk_mq_issue_rq from mmc_mq_queue_rq+0x194/0x218
[  243.792018]  mmc_mq_queue_rq from __blk_mq_issue_directly+0x40/0x9c
[  243.792070]  __blk_mq_issue_directly from blk_mq_plug_issue_direct+0x78/0xcc
[  243.792117]  blk_mq_plug_issue_direct from blk_mq_flush_plug_list+0x19c/0x3a4
[  243.792164]  blk_mq_flush_plug_list from blk_add_rq_to_plug+0xe4/0xf4
[  243.792209]  blk_add_rq_to_plug from blk_mq_submit_bio+0x4e8/0x5c8
[  243.792255]  blk_mq_submit_bio from __submit_bio+0x44/0xc8
[  243.792300]  __submit_bio from submit_bio_noacct_nocheck+0x184/0x2ec
[  243.792339]  submit_bio_noacct_nocheck from __block_write_full_folio+0x26c/0x398
[  243.792398]  __block_write_full_folio from write_cache_pages+0x7c/0xa0
[  243.792450]  write_cache_pages from blkdev_writepages+0x44/0x80
[  243.792492]  blkdev_writepages from do_writepages+0xd4/0x200
[  243.792533]  do_writepages from filemap_fdatawrite_wbc+0x4c/0x60
[  243.792577]  filemap_fdatawrite_wbc from __filemap_fdatawrite_range+0x68/0x8c
[  243.792621]  __filemap_fdatawrite_range from filemap_write_and_wait_range+0x54/0x90
[  243.792665]  filemap_write_and_wait_range from sync_blockdev+0x30/0x38
[  243.792706]  sync_blockdev from bdev_release+0x40/0xfc
[  243.792742]  bdev_release from blkdev_release+0x14/0x1c
[  243.792780]  blkdev_release from __fput+0x110/0x218
[  243.792834]  __fput from sys_close+0x34/0x5c
[  243.792881]  sys_close from ret_fast_syscall+0x0/0x54
[  243.792923] Exception stack(0xf0fc5fa8 to 0xf0fc5ff0)
[  243.792953] 5fa0:                   00000000 00000000 00000001 00000000 00000000 00000000
[  243.792984] 5fc0: 00000000 00000000 004e0974 00000006 beb397ec 00000000 00000000 00000000
[  243.793010] 5fe0: beb39438 beb39428 b6f768a7 b6f761e4
[  243.793040] Kernel panic - not syncing: hung_task: blocked tasks
[  243.793060] CPU: 0 UID: 0 PID: 34 Comm: khungtaskd Not tainted 6.13.0 #9
[  243.793091] Hardware name: Generic DT based system
[  243.793108] Call trace:
[  243.793121]  unwind_backtrace from show_stack+0x18/0x1c
[  243.793174]  show_stack from dump_stack_lvl+0x50/0x64
[  243.793222]  dump_stack_lvl from panic+0x110/0x358
[  243.793265]  panic from watchdog+0x164/0x3dc
[  243.793319]  watchdog from kthread+0x10c/0x114
[  243.793375]  kthread from ret_from_fork+0x14/0x28
[  243.793414] Exception stack(0xf08f5fb0 to 0xf08f5ff8)
[  243.793440] 5fa0:                                     00000000 00000000 00000000 00000000
[  243.793467] 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[  243.793492] 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000