Hi,
the format FS command will hung up with ublk device.
# ublk --version
ublksrv 1.1-7-gf01c509
kerne: 6.9.0-rc4.kasan
nvme0n1 259:1 0 1.5T 0 disk
└─nvme0n1p1 259:2 0 5G 0 part
# ublk add -t loop -f /dev/nvme0n1p1
dev id 0: nr_hw_queues 1 queue_depth 128 block size 4096 dev_capacity 10485760
max rq size 524288 daemon pid 3227 flags 0x42 state LIVE
ublkc: 245:0 ublkb: 259:3 owner: 0:0
queue 0: tid 3228 affinity(0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
18 19 20 21 22 23 24 25 26 27 28 29 30 31 )
target {"backing_file":"/dev/nvme0n1p1","dev_size":5368709120,"direct_io":1,"name":"loop","type":1}
# mkfs.xfs -f /dev/ublkb0 << can not finish, pid 3239
meta-data=/dev/ublkb0 isize=512 agcount=4, agsize=327680 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=1, rmapbt=0
= reflink=1 bigtime=1 inobtcount=1 nrext64=0
data = bsize=4096 blocks=1310720, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=16384, version=2
= sectsz=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# cat /proc/3239/stack
[<0>] rq_qos_wait+0x12a/0x1f0
[<0>] wbt_wait+0x11a/0x240
[<0>] __rq_qos_throttle+0x49/0x90
[<0>] blk_mq_submit_bio+0x58c/0x19d0
[<0>] submit_bio_noacct_nocheck+0x40d/0x780
[<0>] blk_next_bio+0x41/0x50
[<0>] __blkdev_issue_zero_pages+0x1ba/0x370
[<0>] blkdev_issue_zeroout+0x1a7/0x390
[<0>] blkdev_fallocate+0x264/0x3d0
[<0>] vfs_fallocate+0x2b0/0xad0
[<0>] __x64_sys_fallocate+0xb4/0x100
[<0>] do_syscall_64+0x7b/0x160
[<0>] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 862.171377] INFO: task mkfs.xfs:3239 blocked for more than 122 seconds.
[ 862.178073] Not tainted 6.9.0-rc4.kasan+ #1
[ 862.182820] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
[ 862.190721] task:mkfs.xfs state:D stack:0 pid:3239
tgid:3239 ppid:1801 flags:0x00004002
[ 862.190733] Call Trace:
[ 862.190737] <TASK>
[ 862.190742] __schedule+0x65f/0x15a0
[ 862.190759] ? blk_mq_flush_plug_list.part.0+0xd7/0x4a0
[ 862.190774] ? __pfx___schedule+0x10/0x10
[ 862.190779] ? __blk_flush_plug+0x286/0x4a0
[ 862.190790] ? __pfx___blk_flush_plug+0x10/0x10
[ 862.190795] ? kmem_cache_alloc+0x145/0x390
[ 862.190803] ? __pfx_rq_wait_inc_below+0x10/0x10
[ 862.190812] ? __pfx_wbt_inflight_cb+0x10/0x10
[ 862.190820] schedule+0x70/0x1b0
[ 862.190826] io_schedule+0xc0/0x130
[ 862.190832] rq_qos_wait+0x12a/0x1f0
[ 862.190840] ? __pfx_rq_qos_wait+0x10/0x10
[ 862.190845] ? __pfx_rq_qos_wake_function+0x10/0x10
[ 862.190850] ? __pfx_wbt_inflight_cb+0x10/0x10
[ 862.190856] ? submit_bio_noacct_nocheck+0x78/0x780
[ 862.190862] wbt_wait+0x11a/0x240
[ 862.190868] ? __pfx_wbt_wait+0x10/0x10
[ 862.190874] __rq_qos_throttle+0x49/0x90
[ 862.190880] blk_mq_submit_bio+0x58c/0x19d0
[ 862.190888] ? __pfx_blk_mq_submit_bio+0x10/0x10
[ 862.190893] ? bio_associate_blkg_from_css+0x246/0xad0
[ 862.190901] ? blk_cgroup_bio_start+0x281/0x3e0
[ 862.190908] submit_bio_noacct_nocheck+0x40d/0x780
[ 862.190912] ? bio_alloc_bioset+0x43c/0x770
[ 862.190923] ? __pfx_submit_bio_noacct_nocheck+0x10/0x10
[ 862.190929] ? submit_bio_noacct+0x210/0x1780
[ 862.190935] blk_next_bio+0x41/0x50
[ 862.190939] __blkdev_issue_zero_pages+0x1ba/0x370
[ 862.190948] ? __pfx_vfs_write+0x10/0x10
[ 862.190957] blkdev_issue_zeroout+0x1a7/0x390
[ 862.190964] ? __pfx_blkdev_issue_zeroout+0x10/0x10
[ 862.190974] blkdev_fallocate+0x264/0x3d0
[ 862.190981] vfs_fallocate+0x2b0/0xad0
[ 862.190989] __x64_sys_fallocate+0xb4/0x100
[ 862.190994] do_syscall_64+0x7b/0x160
[ 862.191005] ? __vm_munmap+0x139/0x230
[ 862.191012] ? __pfx___vm_munmap+0x10/0x10
[ 862.191016] ? fpregs_restore_userregs+0xe3/0x1f0
[ 862.191029] ? syscall_exit_work+0xff/0x130
[ 862.191037] ? syscall_exit_to_user_mode+0x78/0x200
[ 862.191045] ? do_syscall_64+0x87/0x160
[ 862.191050] ? do_user_addr_fault+0x477/0xad0
[ 862.191061] ? exc_page_fault+0x59/0xc0
[ 862.191067] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 862.191077] RIP: 0033:0x7f2c9e3025da
[ 862.191083] RSP: 002b:00007ffd2f328b38 EFLAGS: 00000246 ORIG_RAX:
000000000000011d
[ 862.191089] RAX: ffffffffffffffda RBX: 00000000a0009000 RCX: 00007f2c9e3025da
[ 862.191094] RDX: 00000000a0009000 RSI: 0000000000000010 RDI: 0000000000000004
[ 862.191097] RBP: 0000000000020000 R08: 0000000000000000 R09: 0000000000000000
[ 862.191100] R10: 0000000004000000 R11: 0000000000000246 R12: 00005629d6f66870
[ 862.191104] R13: 00007ffd2f329260 R14: 0000000000000004 R15: 0000000000000002
[ 862.191111] </TASK
