[syzbot] [mmc?] INFO: task hung in mmc_io_rw_direct_host
From: syzbot
Date: Sun Sep 06 2026 - 14:05:26 EST
Hello,
syzbot found the following issue on:
HEAD commit: 0d9ff90a5422 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16126cf9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8c5c3949d762a91f
dashboard link: https://syzkaller.appspot.com/bug?extid=fd993974345f022e97f2
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d40c962715ec/disk-0d9ff90a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e76513f6d7e7/vmlinux-0d9ff90a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/40a69dadb7ab/bzImage-0d9ff90a.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fd993974345f022e97f2@xxxxxxxxxxxxxxxxxxxxxxxxx
INFO: task kworker/0:1:10 blocked for mor
INFO: task kworker/0:1:10 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:1 state:D stack:23304 pid:10 tgid:10 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: events_freezable mmc_rescan
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5520 [inline]
__schedule+0x1259/0x6920 kernel/sched/core.c:7270
__schedule_loop kernel/sched/core.c:7347 [inline]
schedule+0xdd/0x2c0 kernel/sched/core.c:7362
schedule_timeout+0x1b2/0x280 kernel/time/sleep_timeout.c:75
do_wait_for_common kernel/sched/completion.c:100 [inline]
__wait_for_common+0x2e7/0x4c0 kernel/sched/completion.c:121
mmc_wait_for_req_done+0xcd/0x3d0 drivers/mmc/core/core.c:408
mmc_wait_for_req+0x207/0x2c0 drivers/mmc/core/core.c:619
mmc_wait_for_cmd+0x154/0x200 drivers/mmc/core/core.c:645
mmc_io_rw_direct_host+0x126/0x330 drivers/mmc/core/sdio_ops.c:83
sdio_reset+0x92/0x240 drivers/mmc/core/sdio_ops.c:209
mmc_rescan_try_freq drivers/mmc/core/core.c:2121 [inline]
mmc_rescan+0xba9/0x11c0 drivers/mmc/core/core.c:2316
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
process_scheduled_works kernel/workqueue.c:3479 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
INFO: task kworker/0:5:5708 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:5 state:D stack:20216 pid:5708 tgid:5708 ppid:2 task_flags:0x4288060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5520 [inline]
__schedule+0x1259/0x6920 kernel/sched/core.c:7270
__schedule_loop kernel/sched/core.c:7347 [inline]
schedule+0xdd/0x2c0 kernel/sched/core.c:7362
schedule_timeout+0x1b2/0x280 kernel/time/sleep_timeout.c:75
do_wait_for_common kernel/sched/completion.c:100 [inline]
__wait_for_common+0x2e7/0x4c0 kernel/sched/completion.c:121
__flush_work+0x7c7/0xcb0 kernel/workqueue.c:4448
__cancel_work_sync kernel/workqueue.c:4568 [inline]
cancel_delayed_work_sync+0xd1/0xf0 kernel/workqueue.c:4642
__mmc_stop_host drivers/mmc/core/core.c:2368 [inline]
__mmc_stop_host drivers/mmc/core/core.c:2357 [inline]
mmc_stop_host+0xe9/0x400 drivers/mmc/core/core.c:2373
mmc_remove_host+0x15/0x60 drivers/mmc/core/host.c:681
vub300_disconnect+0x12d/0x170 drivers/mmc/host/vub300.c:2387
usb_unbind_interface+0x1dd/0x9e0 drivers/usb/core/driver.c:461
device_remove drivers/base/dd.c:618 [inline]
device_remove+0x12a/0x180 drivers/base/dd.c:610
__device_release_driver drivers/base/dd.c:1349 [inline]
device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
bus_remove_device+0x2bc/0x560 drivers/base/bus.c:664
device_del+0x376/0x9b0 drivers/base/core.c:3965
usb_disable_device+0x367/0x810 drivers/usb/core/message.c:1478
usb_disconnect+0x2e2/0x9a0 drivers/usb/core/hub.c:2350
hub_port_connect drivers/usb/core/hub.c:5420 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5720 [inline]
port_event drivers/usb/core/hub.c:5884 [inline]
hub_event+0x1bb1/0x4420 drivers/usb/core/hub.c:5966
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
process_scheduled_works kernel/workqueue.c:3479 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Showing all locks held in the system:
locks held by kworker/0:1/10: 2, on CPU#0:
#0: ffff88801c05a140 ((wq_completion)events_freezable){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371
#1: ffffc900000f7d08 ((work_completion)(&(&host->detect)->work)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372
locks held by pr/ttyS0/16: 2, last CPU#0:
#0: ffffffff8edd8338 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline]
#0: ffffffff8edd8338 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline]
#0: ffffffff8edd8338 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x49/0x60 kernel/printk/printk.c:291
#1: ffffffff9bc65c78 (&port_lock_key){-.-.}-{3:3}, at: __uart_port_lock_irqsave include/linux/serial_core.h:613 [inline]
#1: ffffffff9bc65c78 (&port_lock_key){-.-.}-{3:3}, at: univ8250_console_device_lock+0x64/0xc0 drivers/tty/serial/8250/8250_core.c:413
locks held by khungtaskd/31: 1, last CPU#1:
#0: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6837
locks held by getty/5358: 2, on CPU#0:
#0: ffff8880363a40a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc9000321e2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14e0 drivers/tty/n_tty.c:2211
locks held by syz-executor/5599: 4, last CPU#0:
#0: ffffffff8ef3cc30 (dup_mmap_sem){++++}-{0:0}, at: dup_mm kernel/fork.c:1542 [inline]
#0: ffffffff8ef3cc30 (dup_mmap_sem){++++}-{0:0}, at: copy_mm kernel/fork.c:1595 [inline]
#0: ffffffff8ef3cc30 (dup_mmap_sem){++++}-{0:0}, at: copy_process+0x4806/0x8370 kernel/fork.c:2307
#1: ffff888032f2c378 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:562 [inline]
#1: ffff888032f2c378 (&mm->mmap_lock){++++}-{4:4}, at: dup_mmap+0x127/0x2370 mm/mmap.c:1716
#2: ffff88802a209078 (&mm->mmap_lock/1){+.+.}-{4:4}, at: mmap_write_lock_nested include/linux/mmap_lock.h:552 [inline]
#2: ffff88802a209078 (&mm->mmap_lock/1){+.+.}-{4:4}, at: dup_mmap+0x1c9/0x2370 mm/mmap.c:1723
#3: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#3: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#3: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x2f/0x310 mm/pgtable-generic.c:290
locks held by syz-executor/5600: 4, last CPU#0:
#0: ffffffff8ef3cc30 (dup_mmap_sem){++++}-{0:0}, at: dup_mm kernel/fork.c:1542 [inline]
#0: ffffffff8ef3cc30 (dup_mmap_sem){++++}-{0:0}, at: copy_mm kernel/fork.c:1595 [inline]
#0: ffffffff8ef3cc30 (dup_mmap_sem){++++}-{0:0}, at: copy_process+0x4806/0x8370 kernel/fork.c:2307
#1: ffff88802a6669b8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:562 [inline]
#1: ffff88802a6669b8 (&mm->mmap_lock){++++}-{4:4}, at: dup_mmap+0x127/0x2370 mm/mmap.c:1716
#2: ffff88801c087678 (&mm->mmap_lock/1){+.+.}-{4:4}, at: mmap_write_lock_nested include/linux/mmap_lock.h:552 [inline]
#2: ffff88801c087678 (&mm->mmap_lock/1){+.+.}-{4:4}, at: dup_mmap+0x1c9/0x2370 mm/mmap.c:1723
#3: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#3: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#3: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x2f/0x310 mm/pgtable-generic.c:290
locks held by syz-executor/5602: 1, last CPU#1:
#0: ffff88807b45c460 (sb_writers#6){.+.+}-{0:0}, at: filename_unlinkat+0x1ad/0x730 fs/namei.c:5696
locks held by kworker/0:5/5708: 5, on CPU#0:
#0: ffff888023ab7d40 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371
#1: ffffc90002e17d08 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372
#2: ffff88802a8a41d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff88802a8a41d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x1bb/0x4420 drivers/usb/core/hub.c:5912
#3: ffff88804cae71d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#3: ffff88804cae71d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0x10a/0x9a0 drivers/usb/core/hub.c:2341
#4: ffff888035c291a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff888035c291a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline]
#4: ffff888035c291a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb2/0x620 drivers/base/dd.c:1369
locks held by syz.4.1228/9913: 1, last CPU#1:
#0: ffff88802a5ea460 (sb_writers#6){.+.+}-{0:0}, at: get_signal+0x1f2a/0x21e0 kernel/signal.c:3024
locks held by syz-executor/9984: 5, last CPU#0:
#0: ffff8880374aa460 (sb_writers#6){.+.+}-{0:0}, at: filename_create+0x10d/0x400 fs/namei.c:5085
#1: ffff888055acb8d0 (&type->i_mutex_dir_key#5/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1069 [inline]
#1: ffff888055acb8d0 (&type->i_mutex_dir_key#5/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2918 [inline]
#1: ffff888055acb8d0 (&type->i_mutex_dir_key#5/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2942 [inline]
#1: ffff888055acb8d0 (&type->i_mutex_dir_key#5/1){+.+.}-{4:4}, at: filename_create+0x1c0/0x400 fs/namei.c:5092
#2: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#2: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#2: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: security_sid_to_context_core+0x21f/0x700 security/selinux/ss/services.c:1402
#3: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#3: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#3: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: sidtab_sid2str_get+0x84/0x670 security/selinux/ss/sidtab.c:617
#4: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#4: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#4: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
#4: ffffffff8edec060 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xbd/0x2090 arch/x86/kernel/unwind_orc.c:495
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:123
nmi_trigger_cpumask_backtrace+0x21f/0x2a0 lib/nmi_backtrace.c:66
trigger_all_cpu_backtrace include/linux/nmi.h:164 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x141/0x190 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xcb1/0x1030 kernel/hung_task.c:561
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 16 Comm: pr/ttyS0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:delay_tsc+0x32/0xc0 arch/x86/lib/delay.c:77
Code: fd bf 01 00 00 00 41 54 55 53 e8 d9 59 08 f6 e8 04 7e 01 00 41 89 c4 0f 01 f9 66 90 48 c1 e2 20 48 09 c2 48 89 d5 eb 16 f3 90 <bf> 01 00 00 00 e8 b4 59 08 f6 e8 df 7d 01 00 44 39 e0 75 36 0f 01
RSP: 0018:ffffc90000157950 EFLAGS: 00000082
RAX: 8000000000000002 RBX: 000000cbca961e49 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff8c620f00 RDI: 0000000000000001
RBP: 000000cbca961bc5 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000814 R11: 205d313354202020 R12: 0000000000000000
R13: 0000000000000af1 R14: fffffbfff378cbe9 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff888123b5f000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f73f732d380 CR3: 000000005ca75000 CR4: 00000000003526f0
Call Trace:
<TASK>
udelay include/asm-generic/delay.h:62 [inline]
wait_for_lsr+0xf3/0x210 drivers/tty/serial/8250/8250_port.c:2019
serial8250_fifo_wait_for_lsr_thre+0x5f/0xd0 drivers/tty/serial/8250/8250_port.c:3270
__serial8250_console_fifo_write+0xa5/0x290 drivers/tty/serial/8250/8250_port.c:3345
serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3378 [inline]
__serial8250_console_write drivers/tty/serial/8250/8250_port.c:3429 [inline]
serial8250_console_write+0xf46/0x1330 drivers/tty/serial/8250/8250_port.c:3493
nbcon_emit_next_record+0x8f7/0xa70 kernel/printk/nbcon.c:1070
nbcon_emit_one+0x1a8/0x2b0 kernel/printk/nbcon.c:1157
nbcon_kthread_func+0x613/0x7d0 kernel/printk/nbcon.c:1271
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
---
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