[bug report] WARNING: block/blk-mq-debugfs.c:620 at debugfs_create_files.isra.0+0x54/0x60, CPU#220: kworker/u1036:7/70421

[bug report] WARNING: block/blk-mq-debugfs.c:620 at debugfs_create_files.isra.0+0x54/0x60, CPU#220: kworker/u1036:7/70421

[Yi Zhang]

Hello

CKI reported the following failure today. Seems it was introduced from
the recently blk-mq-debugfs update, please help check and let me know
if you need any testing/info.

Reproducer: blktests nvme/tcp nvme/005
Commit message: Merge branch 'for-7.0/block' into for-next

dmesg:
[  951.319384] run blktests nvme/005 at 2026-02-02 17:59:35
[  951.346116] loop0: detected capacity change from 0 to 2097152
[  951.356428] nvmet: adding nsid 1 to subsystem blktests-subsystem-1
[  951.370823] nvmet_tcp: enabling port 0 (127.0.0.1:4420)
[  951.397438] nvmet: Created nvm controller 1 for subsystem
blktests-subsystem-1 for NQN
nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349.
[  951.412081] nvme nvme0: creating 128 I/O queues.
[  951.425914] nvme nvme0: mapped 128/0/0 default/read/poll queues.
[  951.467027] nvme nvme0: new ctrl: NQN "blktests-subsystem-1", addr
127.0.0.1:4420, hostnqn:
nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349
[  951.784608] nvmet: Created nvm controller 2 for subsystem
blktests-subsystem-1 for NQN
nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349.
[  951.798920] nvme nvme0: creating 128 I/O queues.
[  951.871600] nvme nvme0: mapped 128/0/0 default/read/poll queues.
[  951.880680] ------------[ cut here ]------------
[  951.885309] WARNING: block/blk-mq-debugfs.c:620 at
debugfs_create_files.isra.0+0x54/0x60, CPU#220: kworker/u1036:7/70421
[  951.896190] Modules linked in: nvmet_tcp nvmet nvme_tcp
nvme_fabrics nvme nvme_core nvme_keyring nvme_auth rtrs_core rdma_cm
iw_cm ib_cm hkdf nbd loop mlx5_ib ib_uverbs macsec sunrpc ib_core
mlx5_fwctl fwctl rfkill vfat fat amd_atl intel_rapl_msr
intel_rapl_common amd64_edac edac_mce_amd jc42 kvm_amd ee1004 joydev
wmi_bmof mlx5_core kvm irqbypass mlxfw rapl psample tls ptdma ipmi_si
ipmi_devintf pcspkr ipmi_msghandler acpi_cpufreq i2c_piix4 k10temp
i2c_smbus fuse nfnetlink zram lz4hc_compress lz4_compress xfs ast
i2c_algo_bit ghash_clmulni_intel wmi sp5100_tco i2c_dev [last
unloaded: nvmet]
[  951.948577] CPU: 220 UID: 0 PID: 70421 Comm: kworker/u1036:7 Not
tainted 6.19.0-rc7 #1 PREEMPT(lazy)
[  951.957814] Hardware name: AMD Corporation DAYTONA_X/DAYTONA_X,
BIOS RYM100GA 01/13/2025
[  951.965941] Workqueue: nvme-reset-wq nvme_reset_ctrl_work [nvme_tcp]
[  951.972321] RIP: 0010:debugfs_create_files.isra.0+0x54/0x60
[  951.977911] Code: 48 89 d9 4d 89 e0 48 89 ea 49 c7 c1 20 20 73 9a
48 83 c3 28 e8 bd 57 d9 ff 48 8b 3b 48 85 ff 75 db 5b 5d 41 5c e9 f7
b6 51 ff <0f> 0b eb be 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90
90 90
[  951.996673] RSP: 0018:ffffd137f8ee3c90 EFLAGS: 00010202
[  952.001919] RAX: ffff8e3a49aa6c00 RBX: ffffffff9a731e00 RCX: ffffffff9a731e00
[  952.009070] RDX: ffff8e3a831ab000 RSI: ffff8e3a49aa6c00 RDI: 0000000000000001
[  952.016227] RBP: ffff8e3a49aa6c00 R08: 0000000000000064 R09: 0000000000000000
[  952.023396] R10: ffff8e3a1c6a2540 R11: 0000000000000000 R12: ffff8e3a831ab000
[  952.030607] R13: ffff8e3a64c03620 R14: ffffd137f8ee3d38 R15: ffff8e3a8c43e400
[  952.037815] FS:  0000000000000000(0000) GS:ffff8e5601f7b000(0000)
knlGS:0000000000000000
[  952.045946] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  952.051708] CR2: 00007f310853ef58 CR3: 00000037aac2e003 CR4: 0000000000f70ef0
[  952.058856] PKRU: 55555554
[  952.061579] Call Trace:
[  952.064048]  <TASK>
[  952.066159]  blk_mq_debugfs_register_hctx+0x97/0x150
[  952.071136]  ? srso_alias_return_thunk+0x5/0xfbef5
[  952.075945]  blk_mq_debugfs_register_hctxs+0x4e/0x70
[  952.080924]  __blk_mq_update_nr_hw_queues+0x218/0x390
[  952.085991]  blk_mq_update_nr_hw_queues+0x39/0x50
[  952.090714]  nvme_tcp_configure_io_queues.cold+0x1ac/0x35e [nvme_tcp]
[  952.097175]  nvme_tcp_setup_ctrl+0xab/0x250 [nvme_tcp]
[  952.102327]  ? nvme_change_ctrl_state+0x135/0x1b0 [nvme_core]
[  952.108090]  nvme_reset_ctrl_work+0x9a/0xd0 [nvme_tcp]
[  952.113246]  process_one_work+0x18d/0x340
[  952.117266]  worker_thread+0x256/0x3a0
[  952.121030]  ? __pfx_worker_thread+0x10/0x10
[  952.125320]  kthread+0xfc/0x240
[  952.128481]  ? __pfx_kthread+0x10/0x10
[  952.132245]  ? __pfx_kthread+0x10/0x10
[  952.136009]  ret_from_fork+0x126/0x190
[  952.139773]  ? __pfx_kthread+0x10/0x10
[  952.143539]  ret_from_fork_asm+0x1a/0x30
[  952.147484]  </TASK>
[  952.149687] ---[ end trace 0000000000000000 ]---
[  952.167930] nvme nvme0: Removing ctrl: NQN "blktests-subsystem-1"
[  952.195424] block nvme0n1: no available path - failing I/O
[  952.200938] block nvme0n1: no available path - failing I/O
[  952.206483] buffer_io_error: 439 callbacks suppressed
[  952.206486] Buffer I/O error on dev nvme0n1, logical block 262142,
async page read



-- 
Best Regards,
  Yi Zhang

Re: [bug report] WARNING: block/blk-mq-debugfs.c:620 at debugfs_create_files.isra.0+0x54/0x60, CPU#220: kworker/u1036:7/70421

[Yu Kuai]

Hi,

在 2026/2/3 20:28, Yi Zhang 写道:
> Hello
>
> CKI reported the following failure today. Seems it was introduced from
> the recently blk-mq-debugfs update, please help check and let me know
> if you need any testing/info.
>
> Reproducer: blktests nvme/tcp nvme/005
> Commit message: Merge branch 'for-7.0/block' into for-next
>
> dmesg:
> [  951.319384] run blktests nvme/005 at 2026-02-02 17:59:35
> [  951.346116] loop0: detected capacity change from 0 to 2097152
> [  951.356428] nvmet: adding nsid 1 to subsystem blktests-subsystem-1
> [  951.370823] nvmet_tcp: enabling port 0 (127.0.0.1:4420)
> [  951.397438] nvmet: Created nvm controller 1 for subsystem
> blktests-subsystem-1 for NQN
> nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349.
> [  951.412081] nvme nvme0: creating 128 I/O queues.
> [  951.425914] nvme nvme0: mapped 128/0/0 default/read/poll queues.
> [  951.467027] nvme nvme0: new ctrl: NQN "blktests-subsystem-1", addr
> 127.0.0.1:4420, hostnqn:
> nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349
> [  951.784608] nvmet: Created nvm controller 2 for subsystem
> blktests-subsystem-1 for NQN
> nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349.
> [  951.798920] nvme nvme0: creating 128 I/O queues.
> [  951.871600] nvme nvme0: mapped 128/0/0 default/read/poll queues.

Thanks for the test!

Looks like this is because blk_mq_update_nr_hw_queues() is called with queue
already frozen from nvme-tcp, nvme-rdma, nvme-apple:

nvme_start_freeze()
blk_mq_update_nr_hw_queues()
nvme_unfreeze()

And recent commit add a WARN_ON() check for this. This looks fine, but I'm not
quite sure if it's ok to remove the freeze queue before blk_mq_update_nr_hw_queues().

> [  951.880680] ------------[ cut here ]------------
> [  951.885309] WARNING: block/blk-mq-debugfs.c:620 at
> debugfs_create_files.isra.0+0x54/0x60, CPU#220: kworker/u1036:7/70421
> [  951.896190] Modules linked in: nvmet_tcp nvmet nvme_tcp
> nvme_fabrics nvme nvme_core nvme_keyring nvme_auth rtrs_core rdma_cm
> iw_cm ib_cm hkdf nbd loop mlx5_ib ib_uverbs macsec sunrpc ib_core
> mlx5_fwctl fwctl rfkill vfat fat amd_atl intel_rapl_msr
> intel_rapl_common amd64_edac edac_mce_amd jc42 kvm_amd ee1004 joydev
> wmi_bmof mlx5_core kvm irqbypass mlxfw rapl psample tls ptdma ipmi_si
> ipmi_devintf pcspkr ipmi_msghandler acpi_cpufreq i2c_piix4 k10temp
> i2c_smbus fuse nfnetlink zram lz4hc_compress lz4_compress xfs ast
> i2c_algo_bit ghash_clmulni_intel wmi sp5100_tco i2c_dev [last
> unloaded: nvmet]
> [  951.948577] CPU: 220 UID: 0 PID: 70421 Comm: kworker/u1036:7 Not
> tainted 6.19.0-rc7 #1 PREEMPT(lazy)
> [  951.957814] Hardware name: AMD Corporation DAYTONA_X/DAYTONA_X,
> BIOS RYM100GA 01/13/2025
> [  951.965941] Workqueue: nvme-reset-wq nvme_reset_ctrl_work [nvme_tcp]
> [  951.972321] RIP: 0010:debugfs_create_files.isra.0+0x54/0x60
> [  951.977911] Code: 48 89 d9 4d 89 e0 48 89 ea 49 c7 c1 20 20 73 9a
> 48 83 c3 28 e8 bd 57 d9 ff 48 8b 3b 48 85 ff 75 db 5b 5d 41 5c e9 f7
> b6 51 ff <0f> 0b eb be 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90
> 90 90
> [  951.996673] RSP: 0018:ffffd137f8ee3c90 EFLAGS: 00010202
> [  952.001919] RAX: ffff8e3a49aa6c00 RBX: ffffffff9a731e00 RCX: ffffffff9a731e00
> [  952.009070] RDX: ffff8e3a831ab000 RSI: ffff8e3a49aa6c00 RDI: 0000000000000001
> [  952.016227] RBP: ffff8e3a49aa6c00 R08: 0000000000000064 R09: 0000000000000000
> [  952.023396] R10: ffff8e3a1c6a2540 R11: 0000000000000000 R12: ffff8e3a831ab000
> [  952.030607] R13: ffff8e3a64c03620 R14: ffffd137f8ee3d38 R15: ffff8e3a8c43e400
> [  952.037815] FS:  0000000000000000(0000) GS:ffff8e5601f7b000(0000)
> knlGS:0000000000000000
> [  952.045946] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  952.051708] CR2: 00007f310853ef58 CR3: 00000037aac2e003 CR4: 0000000000f70ef0
> [  952.058856] PKRU: 55555554
> [  952.061579] Call Trace:
> [  952.064048]  <TASK>
> [  952.066159]  blk_mq_debugfs_register_hctx+0x97/0x150
> [  952.071136]  ? srso_alias_return_thunk+0x5/0xfbef5
> [  952.075945]  blk_mq_debugfs_register_hctxs+0x4e/0x70
> [  952.080924]  __blk_mq_update_nr_hw_queues+0x218/0x390
> [  952.085991]  blk_mq_update_nr_hw_queues+0x39/0x50
> [  952.090714]  nvme_tcp_configure_io_queues.cold+0x1ac/0x35e [nvme_tcp]
> [  952.097175]  nvme_tcp_setup_ctrl+0xab/0x250 [nvme_tcp]
> [  952.102327]  ? nvme_change_ctrl_state+0x135/0x1b0 [nvme_core]
> [  952.108090]  nvme_reset_ctrl_work+0x9a/0xd0 [nvme_tcp]
> [  952.113246]  process_one_work+0x18d/0x340
> [  952.117266]  worker_thread+0x256/0x3a0
> [  952.121030]  ? __pfx_worker_thread+0x10/0x10
> [  952.125320]  kthread+0xfc/0x240
> [  952.128481]  ? __pfx_kthread+0x10/0x10
> [  952.132245]  ? __pfx_kthread+0x10/0x10
> [  952.136009]  ret_from_fork+0x126/0x190
> [  952.139773]  ? __pfx_kthread+0x10/0x10
> [  952.143539]  ret_from_fork_asm+0x1a/0x30
> [  952.147484]  </TASK>
> [  952.149687] ---[ end trace 0000000000000000 ]---
> [  952.167930] nvme nvme0: Removing ctrl: NQN "blktests-subsystem-1"
> [  952.195424] block nvme0n1: no available path - failing I/O
> [  952.200938] block nvme0n1: no available path - failing I/O
> [  952.206483] buffer_io_error: 439 callbacks suppressed
> [  952.206486] Buffer I/O error on dev nvme0n1, logical block 262142,
> async page read
>
>
>
-- 
Thansk,
Kuai

Re: [bug report] WARNING: block/blk-mq-debugfs.c:620 at debugfs_create_files.isra.0+0x54/0x60, CPU#220: kworker/u1036:7/70421

[Shinichiro Kawasaki]

On Feb 03, 2026 / 20:28, Yi Zhang wrote:
> Hello
> 
> CKI reported the following failure today. Seems it was introduced from
> the recently blk-mq-debugfs update, please help check and let me know
> if you need any testing/info.
> 
> Reproducer: blktests nvme/tcp nvme/005
> Commit message: Merge branch 'for-7.0/block' into for-next
> 
> dmesg:
> [  951.319384] run blktests nvme/005 at 2026-02-02 17:59:35
> [  951.346116] loop0: detected capacity change from 0 to 2097152
> [  951.356428] nvmet: adding nsid 1 to subsystem blktests-subsystem-1
> [  951.370823] nvmet_tcp: enabling port 0 (127.0.0.1:4420)
> [  951.397438] nvmet: Created nvm controller 1 for subsystem
> blktests-subsystem-1 for NQN
> nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349.
> [  951.412081] nvme nvme0: creating 128 I/O queues.
> [  951.425914] nvme nvme0: mapped 128/0/0 default/read/poll queues.
> [  951.467027] nvme nvme0: new ctrl: NQN "blktests-subsystem-1", addr
> 127.0.0.1:4420, hostnqn:
> nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349
> [  951.784608] nvmet: Created nvm controller 2 for subsystem
> blktests-subsystem-1 for NQN
> nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349.
> [  951.798920] nvme nvme0: creating 128 I/O queues.
> [  951.871600] nvme nvme0: mapped 128/0/0 default/read/poll queues.
> [  951.880680] ------------[ cut here ]------------
> [  951.885309] WARNING: block/blk-mq-debugfs.c:620 at
> debugfs_create_files.isra.0+0x54/0x60, CPU#220: kworker/u1036:7/70421

FYI, I also observe this WARN at debugfs_create_files() using the blktests test
case zbd/012. When I repeat zbd/012 several times on the kernel with the tag
next-20260204, the WARN below is reported:

[ 1304.543824] [  T12755] ------------[ cut here ]------------
[ 1304.545792] [  T12755] WARNING: block/blk-mq-debugfs.c:620 at debugfs_create_files+0x247/0x2c0, CPU#2: check/12755
[ 1304.547377] [  T12755] Modules linked in: scsi_debug null_blk nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables qrtr sunrpc 9pnet_virtio 9pnet pcspkr netfs i2c_piix4 i2c_smbus loop fuse dm_multipath nfnetlink vsock_loopback vmw_vsock_virtio_transport_common zram vsock xfs bochs drm_client_lib drm_shmem_helper drm_kms_helper nvme drm nvme_core floppy sym53c8xx nvme_keyring e1000 scsi_transport_spi nvme_auth hkdf serio_raw ata_generic pata_acpi i2c_dev qemu_fw_cfg [last unloaded: scsi_debug]
[ 1304.554851] [  T12755] CPU: 2 UID: 0 PID: 12755 Comm: check Not tainted 6.19.0-rc8-next-20260204 #383 PREEMPT(full) 
[ 1304.556421] [  T12755] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-4.fc42 04/01/2014
[ 1304.557886] [  T12755] RIP: 0010:debugfs_create_files+0x247/0x2c0
[ 1304.559074] [  T12755] Code: ff e8 1d b0 83 01 83 f8 01 0f 85 67 fe ff ff 0f 0b e9 60 fe ff ff 0f 0b e9 59 fe ff ff 48 89 ef e8 2e 59 69 ff e9 07 fe ff ff <0f> 0b e9 6e ff ff ff e8 fd 58 69 ff e9 9a fe ff ff 48 89 df e8 30
[ 1304.562112] [  T12755] RSP: 0018:ffff888147b77530 EFLAGS: 00010202
[ 1304.563343] [  T12755] RAX: 0000000000000000 RBX: ffffffffaa567360 RCX: 0000000000000001
[ 1304.564728] [  T12755] RDX: 0000000000000001 RSI: ffffffffaae6910d RDI: ffff888130361a48
[ 1304.566104] [  T12755] RBP: ffffffffabe49734 R08: 0000000000000001 R09: ffffed1022804075
[ 1304.567487] [  T12755] R10: 0000000000000002 R11: ffff88812610c390 R12: ffff8881140202f0
[ 1304.568850] [  T12755] R13: ffff888130361310 R14: ffff888130361310 R15: ffffffffaa567af0
[ 1304.570246] [  T12755] FS:  00007f40d67a1740(0000) GS:ffff8884011ea000(0000) knlGS:0000000000000000
[ 1304.571721] [  T12755] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1304.573019] [  T12755] CR2: 000000001e02a810 CR3: 00000001148f6000 CR4: 00000000000006f0
[ 1304.574409] [  T12755] Call Trace:
[ 1304.575361] [  T12755]  <TASK>
[ 1304.576229] [  T12755]  blk_mq_sched_reg_debugfs+0x28/0xe0
[ 1304.577287] [  T12755]  elevator_change_done+0x2f2/0x610
[ 1304.578342] [  T12755]  ? lockdep_hardirqs_on_prepare+0x50/0x1b0
[ 1304.579452] [  T12755]  ? __pfx_elevator_change_done+0x10/0x10
[ 1304.580469] [  T12755]  ? find_held_lock+0x2b/0x80
[ 1304.581346] [  T12755]  ? elevator_change+0x2ed/0x4f0
[ 1304.582246] [  T12755]  ? lock_release+0x1a7/0x320
[ 1304.583142] [  T12755]  ? __pfx_sysfs_kf_write+0x10/0x10
[ 1304.584087] [  T12755]  elevator_change+0x283/0x4f0
[ 1304.584970] [  T12755]  ? __pfx_sysfs_kf_write+0x10/0x10
[ 1304.585887] [  T12755]  elv_iosched_store+0x31d/0x3a0
[ 1304.586784] [  T12755]  ? __pfx_elv_iosched_store+0x10/0x10
[ 1304.587724] [  T12755]  ? lock_acquire+0x1b0/0x340
[ 1304.588597] [  T12755]  ? kernfs_fop_write_iter+0x257/0x5e0
[ 1304.589523] [  T12755]  ? __pfx___might_resched+0x10/0x10
[ 1304.590396] [  T12755]  ? __might_fault+0x97/0x140
[ 1304.591265] [  T12755]  ? __pfx_sysfs_kf_write+0x10/0x10
[ 1304.592185] [  T12755]  queue_attr_store+0x235/0x360
[ 1304.593064] [  T12755]  ? __lock_acquire+0x497/0x2230
[ 1304.593929] [  T12755]  ? __pfx_queue_attr_store+0x10/0x10
[ 1304.594787] [  T12755]  ? lock_acquire+0x1b0/0x340
[ 1304.595629] [  T12755]  ? sysfs_file_kobj+0x1d/0x1b0
[ 1304.596473] [  T12755]  ? lock_acquire+0x1c0/0x340
[ 1304.597261] [  T12755]  ? find_held_lock+0x2b/0x80
[ 1304.598107] [  T12755]  ? sysfs_file_kobj+0xaf/0x1b0
[ 1304.598937] [  T12755]  ? lock_release+0x1a7/0x320
[ 1304.599766] [  T12755]  ? sysfs_file_kobj+0xb9/0x1b0
[ 1304.600598] [  T12755]  ? sysfs_kf_write+0x61/0x160
[ 1304.601378] [  T12755]  ? __pfx_sysfs_kf_write+0x10/0x10
[ 1304.602276] [  T12755]  kernfs_fop_write_iter+0x3d6/0x5e0
[ 1304.603148] [  T12755]  ? __pfx_kernfs_fop_write_iter+0x10/0x10
[ 1304.604048] [  T12755]  vfs_write+0x523/0xf80
[ 1304.604784] [  T12755]  ? arch_stack_walk+0xb3/0x100
[ 1304.605573] [  T12755]  ? __pfx_vfs_write+0x10/0x10
[ 1304.606283] [  T12755]  ? lock_acquire+0x1b0/0x340
[ 1304.607038] [  T12755]  ? get_close_on_exec+0x1f/0x230
[ 1304.607774] [  T12755]  ? get_close_on_exec+0xfc/0x230
[ 1304.608502] [  T12755]  ? lock_release+0x1a7/0x320
[ 1304.609150] [  T12755]  ksys_write+0xfb/0x200
[ 1304.609803] [  T12755]  ? __pfx_ksys_write+0x10/0x10
[ 1304.610495] [  T12755]  ? lock_release+0x1a7/0x320
[ 1304.611181] [  T12755]  do_syscall_64+0x136/0x1540
[ 1304.611845] [  T12755]  ? do_wp_page+0x168d/0x3610
[ 1304.612505] [  T12755]  ? lock_acquire+0x1b0/0x340
[ 1304.613151] [  T12755]  ? __pfx_do_wp_page+0x10/0x10
[ 1304.613803] [  T12755]  ? lock_acquire+0x1b0/0x340
[ 1304.614439] [  T12755]  ? do_raw_spin_lock+0x124/0x260
[ 1304.615078] [  T12755]  ? lock_acquire+0x1c0/0x340
[ 1304.615697] [  T12755]  ? __pfx_do_raw_spin_lock+0x10/0x10
[ 1304.616369] [  T12755]  ? __pfx_pte_write+0x10/0x10
[ 1304.617022] [  T12755]  ? __handle_mm_fault+0x12b2/0x1d50
[ 1304.617677] [  T12755]  ? __lock_acquire+0x497/0x2230
[ 1304.618336] [  T12755]  ? __pfx_css_rstat_updated+0x10/0x10
[ 1304.619065] [  T12755]  ? lock_acquire+0x1b0/0x340
[ 1304.619677] [  T12755]  ? count_memcg_events_mm.constprop.0+0x22/0x130
[ 1304.620438] [  T12755]  ? rcu_is_watching+0x11/0xb0
[ 1304.621074] [  T12755]  ? count_memcg_events+0x106/0x4a0
[ 1304.621741] [  T12755]  ? find_held_lock+0x2b/0x80
[ 1304.622376] [  T12755]  ? rcu_read_unlock+0x17/0x60
[ 1304.623047] [  T12755]  ? lock_release+0x1a7/0x320
[ 1304.623656] [  T12755]  ? find_held_lock+0x2b/0x80
[ 1304.624290] [  T12755]  ? exc_page_fault+0x83/0x110
[ 1304.624926] [  T12755]  ? lock_release+0x1a7/0x320
[ 1304.625553] [  T12755]  ? rcu_is_watching+0x11/0xb0
[ 1304.626170] [  T12755]  ? irqentry_exit+0xdd/0x6a0
[ 1304.626793] [  T12755]  ? lockdep_hardirqs_on_prepare+0xce/0x1b0
[ 1304.627499] [  T12755]  ? irqentry_exit+0xe2/0x6a0
[ 1304.628114] [  T12755]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 1304.628821] [  T12755] RIP: 0033:0x7f40d681277e
[ 1304.629425] [  T12755] Code: 4d 89 d8 e8 d4 bc 00 00 4c 8b 5d f8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 11 c9 c3 0f 1f 80 00 00 00 00 48 8b 45 10 0f 05 <c9> c3 83 e2 39 83 fa 08 75 e7 e8 13 ff ff ff 0f 1f 00 f3 0f 1e fa
[ 1304.631432] [  T12755] RSP: 002b:00007ffd15db4a60 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
[ 1304.632364] [  T12755] RAX: ffffffffffffffda RBX: 000000000000000c RCX: 00007f40d681277e
[ 1304.633275] [  T12755] RDX: 000000000000000c RSI: 000000001e02a810 RDI: 0000000000000001
[ 1304.634198] [  T12755] RBP: 00007ffd15db4a70 R08: 0000000000000000 R09: 0000000000000000
[ 1304.635127] [  T12755] R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000c
[ 1304.636044] [  T12755] R13: 000000001e02a810 R14: 00007f40d698d5c0 R15: 0000000000000000
[ 1304.636962] [  T12755]  </TASK>
[ 1304.637532] [  T12755] irq event stamp: 6849
[ 1304.638170] [  T12755] hardirqs last  enabled at (6861): [<ffffffffa76e6bae>] __up_console_sem+0x5e/0x70
[ 1304.639207] [  T12755] hardirqs last disabled at (6872): [<ffffffffa76e6b93>] __up_console_sem+0x43/0x70
[ 1304.640247] [  T12755] softirqs last  enabled at (5936): [<ffffffffa7521b66>] __irq_exit_rcu+0x126/0x240
[ 1304.641299] [  T12755] softirqs last disabled at (5925): [<ffffffffa7521b66>] __irq_exit_rcu+0x126/0x240
[ 1304.642338] [  T12755] ---[ end trace 0000000000000000 ]---

Re: [bug report] WARNING: block/blk-mq-debugfs.c:620 at debugfs_create_files.isra.0+0x54/0x60, CPU#220: kworker/u1036:7/70421

[Yu Kuai]

Hi,

在 2026/2/6 15:25, Shinichiro Kawasaki 写道:
> On Feb 03, 2026 / 20:28, Yi Zhang wrote:
>> Hello
>>
>> CKI reported the following failure today. Seems it was introduced from
>> the recently blk-mq-debugfs update, please help check and let me know
>> if you need any testing/info.
>>
>> Reproducer: blktests nvme/tcp nvme/005
>> Commit message: Merge branch 'for-7.0/block' into for-next
>>
>> dmesg:
>> [  951.319384] run blktests nvme/005 at 2026-02-02 17:59:35
>> [  951.346116] loop0: detected capacity change from 0 to 2097152
>> [  951.356428] nvmet: adding nsid 1 to subsystem blktests-subsystem-1
>> [  951.370823] nvmet_tcp: enabling port 0 (127.0.0.1:4420)
>> [  951.397438] nvmet: Created nvm controller 1 for subsystem
>> blktests-subsystem-1 for NQN
>> nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349.
>> [  951.412081] nvme nvme0: creating 128 I/O queues.
>> [  951.425914] nvme nvme0: mapped 128/0/0 default/read/poll queues.
>> [  951.467027] nvme nvme0: new ctrl: NQN "blktests-subsystem-1", addr
>> 127.0.0.1:4420, hostnqn:
>> nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349
>> [  951.784608] nvmet: Created nvm controller 2 for subsystem
>> blktests-subsystem-1 for NQN
>> nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349.
>> [  951.798920] nvme nvme0: creating 128 I/O queues.
>> [  951.871600] nvme nvme0: mapped 128/0/0 default/read/poll queues.
>> [  951.880680] ------------[ cut here ]------------
>> [  951.885309] WARNING: block/blk-mq-debugfs.c:620 at
>> debugfs_create_files.isra.0+0x54/0x60, CPU#220: kworker/u1036:7/70421
> FYI, I also observe this WARN at debugfs_create_files() using the blktests test
> case zbd/012. When I repeat zbd/012 several times on the kernel with the tag
> next-20260204, the WARN below is reported:

Thanks for the test, although queue is unfrozen before debugfs_create_files() from
switching elevator, however, it's still possible queue can be frozen from other
context concurrently.

This warning is not false positive, however, we'll have to fix nvme cases first
before we can fix this.

>
> [ 1304.543824] [  T12755] ------------[ cut here ]------------
> [ 1304.545792] [  T12755] WARNING: block/blk-mq-debugfs.c:620 at debugfs_create_files+0x247/0x2c0, CPU#2: check/12755
> [ 1304.547377] [  T12755] Modules linked in: scsi_debug null_blk nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables qrtr sunrpc 9pnet_virtio 9pnet pcspkr netfs i2c_piix4 i2c_smbus loop fuse dm_multipath nfnetlink vsock_loopback vmw_vsock_virtio_transport_common zram vsock xfs bochs drm_client_lib drm_shmem_helper drm_kms_helper nvme drm nvme_core floppy sym53c8xx nvme_keyring e1000 scsi_transport_spi nvme_auth hkdf serio_raw ata_generic pata_acpi i2c_dev qemu_fw_cfg [last unloaded: scsi_debug]
> [ 1304.554851] [  T12755] CPU: 2 UID: 0 PID: 12755 Comm: check Not tainted 6.19.0-rc8-next-20260204 #383 PREEMPT(full)
> [ 1304.556421] [  T12755] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-4.fc42 04/01/2014
> [ 1304.557886] [  T12755] RIP: 0010:debugfs_create_files+0x247/0x2c0
> [ 1304.559074] [  T12755] Code: ff e8 1d b0 83 01 83 f8 01 0f 85 67 fe ff ff 0f 0b e9 60 fe ff ff 0f 0b e9 59 fe ff ff 48 89 ef e8 2e 59 69 ff e9 07 fe ff ff <0f> 0b e9 6e ff ff ff e8 fd 58 69 ff e9 9a fe ff ff 48 89 df e8 30
> [ 1304.562112] [  T12755] RSP: 0018:ffff888147b77530 EFLAGS: 00010202
> [ 1304.563343] [  T12755] RAX: 0000000000000000 RBX: ffffffffaa567360 RCX: 0000000000000001
> [ 1304.564728] [  T12755] RDX: 0000000000000001 RSI: ffffffffaae6910d RDI: ffff888130361a48
> [ 1304.566104] [  T12755] RBP: ffffffffabe49734 R08: 0000000000000001 R09: ffffed1022804075
> [ 1304.567487] [  T12755] R10: 0000000000000002 R11: ffff88812610c390 R12: ffff8881140202f0
> [ 1304.568850] [  T12755] R13: ffff888130361310 R14: ffff888130361310 R15: ffffffffaa567af0
> [ 1304.570246] [  T12755] FS:  00007f40d67a1740(0000) GS:ffff8884011ea000(0000) knlGS:0000000000000000
> [ 1304.571721] [  T12755] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1304.573019] [  T12755] CR2: 000000001e02a810 CR3: 00000001148f6000 CR4: 00000000000006f0
> [ 1304.574409] [  T12755] Call Trace:
> [ 1304.575361] [  T12755]  <TASK>
> [ 1304.576229] [  T12755]  blk_mq_sched_reg_debugfs+0x28/0xe0
> [ 1304.577287] [  T12755]  elevator_change_done+0x2f2/0x610
> [ 1304.578342] [  T12755]  ? lockdep_hardirqs_on_prepare+0x50/0x1b0
> [ 1304.579452] [  T12755]  ? __pfx_elevator_change_done+0x10/0x10
> [ 1304.580469] [  T12755]  ? find_held_lock+0x2b/0x80
> [ 1304.581346] [  T12755]  ? elevator_change+0x2ed/0x4f0
> [ 1304.582246] [  T12755]  ? lock_release+0x1a7/0x320
> [ 1304.583142] [  T12755]  ? __pfx_sysfs_kf_write+0x10/0x10
> [ 1304.584087] [  T12755]  elevator_change+0x283/0x4f0
> [ 1304.584970] [  T12755]  ? __pfx_sysfs_kf_write+0x10/0x10
> [ 1304.585887] [  T12755]  elv_iosched_store+0x31d/0x3a0
> [ 1304.586784] [  T12755]  ? __pfx_elv_iosched_store+0x10/0x10
> [ 1304.587724] [  T12755]  ? lock_acquire+0x1b0/0x340
> [ 1304.588597] [  T12755]  ? kernfs_fop_write_iter+0x257/0x5e0
> [ 1304.589523] [  T12755]  ? __pfx___might_resched+0x10/0x10
> [ 1304.590396] [  T12755]  ? __might_fault+0x97/0x140
> [ 1304.591265] [  T12755]  ? __pfx_sysfs_kf_write+0x10/0x10
> [ 1304.592185] [  T12755]  queue_attr_store+0x235/0x360
> [ 1304.593064] [  T12755]  ? __lock_acquire+0x497/0x2230
> [ 1304.593929] [  T12755]  ? __pfx_queue_attr_store+0x10/0x10
> [ 1304.594787] [  T12755]  ? lock_acquire+0x1b0/0x340
> [ 1304.595629] [  T12755]  ? sysfs_file_kobj+0x1d/0x1b0
> [ 1304.596473] [  T12755]  ? lock_acquire+0x1c0/0x340
> [ 1304.597261] [  T12755]  ? find_held_lock+0x2b/0x80
> [ 1304.598107] [  T12755]  ? sysfs_file_kobj+0xaf/0x1b0
> [ 1304.598937] [  T12755]  ? lock_release+0x1a7/0x320
> [ 1304.599766] [  T12755]  ? sysfs_file_kobj+0xb9/0x1b0
> [ 1304.600598] [  T12755]  ? sysfs_kf_write+0x61/0x160
> [ 1304.601378] [  T12755]  ? __pfx_sysfs_kf_write+0x10/0x10
> [ 1304.602276] [  T12755]  kernfs_fop_write_iter+0x3d6/0x5e0
> [ 1304.603148] [  T12755]  ? __pfx_kernfs_fop_write_iter+0x10/0x10
> [ 1304.604048] [  T12755]  vfs_write+0x523/0xf80
> [ 1304.604784] [  T12755]  ? arch_stack_walk+0xb3/0x100
> [ 1304.605573] [  T12755]  ? __pfx_vfs_write+0x10/0x10
> [ 1304.606283] [  T12755]  ? lock_acquire+0x1b0/0x340
> [ 1304.607038] [  T12755]  ? get_close_on_exec+0x1f/0x230
> [ 1304.607774] [  T12755]  ? get_close_on_exec+0xfc/0x230
> [ 1304.608502] [  T12755]  ? lock_release+0x1a7/0x320
> [ 1304.609150] [  T12755]  ksys_write+0xfb/0x200
> [ 1304.609803] [  T12755]  ? __pfx_ksys_write+0x10/0x10
> [ 1304.610495] [  T12755]  ? lock_release+0x1a7/0x320
> [ 1304.611181] [  T12755]  do_syscall_64+0x136/0x1540
> [ 1304.611845] [  T12755]  ? do_wp_page+0x168d/0x3610
> [ 1304.612505] [  T12755]  ? lock_acquire+0x1b0/0x340
> [ 1304.613151] [  T12755]  ? __pfx_do_wp_page+0x10/0x10
> [ 1304.613803] [  T12755]  ? lock_acquire+0x1b0/0x340
> [ 1304.614439] [  T12755]  ? do_raw_spin_lock+0x124/0x260
> [ 1304.615078] [  T12755]  ? lock_acquire+0x1c0/0x340
> [ 1304.615697] [  T12755]  ? __pfx_do_raw_spin_lock+0x10/0x10
> [ 1304.616369] [  T12755]  ? __pfx_pte_write+0x10/0x10
> [ 1304.617022] [  T12755]  ? __handle_mm_fault+0x12b2/0x1d50
> [ 1304.617677] [  T12755]  ? __lock_acquire+0x497/0x2230
> [ 1304.618336] [  T12755]  ? __pfx_css_rstat_updated+0x10/0x10
> [ 1304.619065] [  T12755]  ? lock_acquire+0x1b0/0x340
> [ 1304.619677] [  T12755]  ? count_memcg_events_mm.constprop.0+0x22/0x130
> [ 1304.620438] [  T12755]  ? rcu_is_watching+0x11/0xb0
> [ 1304.621074] [  T12755]  ? count_memcg_events+0x106/0x4a0
> [ 1304.621741] [  T12755]  ? find_held_lock+0x2b/0x80
> [ 1304.622376] [  T12755]  ? rcu_read_unlock+0x17/0x60
> [ 1304.623047] [  T12755]  ? lock_release+0x1a7/0x320
> [ 1304.623656] [  T12755]  ? find_held_lock+0x2b/0x80
> [ 1304.624290] [  T12755]  ? exc_page_fault+0x83/0x110
> [ 1304.624926] [  T12755]  ? lock_release+0x1a7/0x320
> [ 1304.625553] [  T12755]  ? rcu_is_watching+0x11/0xb0
> [ 1304.626170] [  T12755]  ? irqentry_exit+0xdd/0x6a0
> [ 1304.626793] [  T12755]  ? lockdep_hardirqs_on_prepare+0xce/0x1b0
> [ 1304.627499] [  T12755]  ? irqentry_exit+0xe2/0x6a0
> [ 1304.628114] [  T12755]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
> [ 1304.628821] [  T12755] RIP: 0033:0x7f40d681277e
> [ 1304.629425] [  T12755] Code: 4d 89 d8 e8 d4 bc 00 00 4c 8b 5d f8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 11 c9 c3 0f 1f 80 00 00 00 00 48 8b 45 10 0f 05 <c9> c3 83 e2 39 83 fa 08 75 e7 e8 13 ff ff ff 0f 1f 00 f3 0f 1e fa
> [ 1304.631432] [  T12755] RSP: 002b:00007ffd15db4a60 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
> [ 1304.632364] [  T12755] RAX: ffffffffffffffda RBX: 000000000000000c RCX: 00007f40d681277e
> [ 1304.633275] [  T12755] RDX: 000000000000000c RSI: 000000001e02a810 RDI: 0000000000000001
> [ 1304.634198] [  T12755] RBP: 00007ffd15db4a70 R08: 0000000000000000 R09: 0000000000000000
> [ 1304.635127] [  T12755] R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000c
> [ 1304.636044] [  T12755] R13: 000000001e02a810 R14: 00007f40d698d5c0 R15: 0000000000000000
> [ 1304.636962] [  T12755]  </TASK>
> [ 1304.637532] [  T12755] irq event stamp: 6849
> [ 1304.638170] [  T12755] hardirqs last  enabled at (6861): [<ffffffffa76e6bae>] __up_console_sem+0x5e/0x70
> [ 1304.639207] [  T12755] hardirqs last disabled at (6872): [<ffffffffa76e6b93>] __up_console_sem+0x43/0x70
> [ 1304.640247] [  T12755] softirqs last  enabled at (5936): [<ffffffffa7521b66>] __irq_exit_rcu+0x126/0x240
> [ 1304.641299] [  T12755] softirqs last disabled at (5925): [<ffffffffa7521b66>] __irq_exit_rcu+0x126/0x240
> [ 1304.642338] [  T12755] ---[ end trace 0000000000000000 ]---
>
-- 
Thansk,
Kuai