INFO: task syz.7.2568:12478 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.2568      state:D stack:27176 pid:12478 tgid:12477 ppid:10296  task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 io_schedule+0xbf/0x130 kernel/sched/core.c:7903
 folio_wait_bit_common+0x3d6/0x9e0 mm/filemap.c:1317
 folio_wait_writeback+0x3c/0x90 mm/page-writeback.c:3124
 __filemap_fdatawait_range+0x11f/0x200 mm/filemap.c:539
 filemap_fdatawait_keep_errors+0x21/0x30 mm/filemap.c:633
 wait_sb_inodes fs/fs-writeback.c:2715 [inline]
 sync_inodes_sb+0x5fa/0xa70 fs/fs-writeback.c:2837
 sync_inodes_one_sb+0x52/0x60 fs/sync.c:77
 __iterate_supers+0x210/0x360 fs/super.c:924
 ksys_sync+0x89/0x150 fs/sync.c:102
 __do_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4e0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe3c938eba9
RSP: 002b:00007fe3ca2a3038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fe3c95d5fa0 RCX: 00007fe3c938eba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fe3c95d5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe3c95d6038 R14: 00007fe3c95d5fa0 R15: 00007ffcf3a7b978
 </TASK>

Showing all locks held in the system:
6 locks held by kworker/0:0/9:
 #0: ffff888143aa7548 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc900000e7d10 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
 #2: ffff888144f46198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:911 [inline]
 #2: ffff888144f46198 (&dev->mutex){....}-{4:4}, at: hub_event+0x1c0/0x4fe0 drivers/usb/core/hub.c:5898
 #3: ffff888022b83198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:911 [inline]
 #3: ffff888022b83198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4b0 drivers/base/dd.c:1006
 #4: ffff888022b81160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:911 [inline]
 #4: ffff888022b81160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4b0 drivers/base/dd.c:1006
 #5: ffff888089441c38 (&dev->ctrl_urb_lock){+.+.}-{4:4}, at: em28xx_write_regs_req+0x145/0x3f0 drivers/media/usb/em28xx/em28xx-core.c:147
1 lock held by khungtaskd/31:
 #0: ffffffff8e5c15a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e5c15a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e5c15a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
2 locks held by getty/5607:
 #0: ffff88803687f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
2 locks held by syz.1.51/6096:
 #0: ffff88807899e428 (sb_writers#13){.+.+}-{0:0}, at: splice_direct_to_actor+0x342/0xa30 fs/splice.c:1105
 #1: ffff8880570d07b8 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: netfs_start_io_direct+0x116/0x260 fs/netfs/locking.c:188
3 locks held by syz.0.1387/9502:
 #0: ffff88807b0de428 (sb_writers#13){.+.+}-{0:0}, at: do_pwritev+0x1a6/0x270 fs/read_write.c:1153
 #1: ffff88806cfcce88 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: netfs_start_io_write+0x59/0x80 fs/netfs/locking.c:112
 #2: ffff88806cfcd240 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_begin_writethrough+0x64/0x1c0 fs/netfs/write_issue.c:626
2 locks held by syz.7.2568/12478:
 #0: ffff88807b0de0e0 (&type->s_umount_key#69){++++}-{4:4}, at: __super_lock fs/super.c:59 [inline]
 #0: ffff88807b0de0e0 (&type->s_umount_key#69){++++}-{4:4}, at: super_lock+0x31c/0x3f0 fs/super.c:121
 #1: ffff88807b0de950 (&s->s_sync_lock){+.+.}-{4:4}, at: wait_sb_inodes fs/fs-writeback.c:2654 [inline]
 #1: ffff88807b0de950 (&s->s_sync_lock){+.+.}-{4:4}, at: sync_inodes_sb+0x231/0xa70 fs/fs-writeback.c:2837

=============================================

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 08/18/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline]
 watchdog+0xf0e/0x1260 kernel/hung_task.c:491
 kthread+0x3c2/0x780 kernel/kthread.c:463
 ret_from_fork+0x56a/0x730 arch/x86/kernel/process.c:148
 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: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: 6d 61 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d d3 56 15 00 fb f4 <e9> cc 09 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffffff8e207e08 EFLAGS: 000002c2
RAX: 00000000001ea031 RBX: 0000000000000000 RCX: ffffffff8b94bb49
RDX: 0000000000000000 RSI: ffffffff8de527c8 RDI: ffffffff8c163300
RBP: fffffbfff1c52ef8 R08: 0000000000000001 R09: ffffed1017086655
R10: ffff8880b84332ab R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff8e2977c0 R14: ffffffff90ab7090 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881246b4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff34354e28 CR3: 000000007fadc000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:757
 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:190 [inline]
 do_idle+0x391/0x510 kernel/sched/idle.c:330
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428
 rest_init+0x16b/0x2b0 init/main.c:744
 start_kernel+0x3ee/0x4d0 init/main.c:1097
 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:307
 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:288
 common_startup_64+0x13e/0x148
 </TASK>