INFO: task syz-executor:10506 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:22456 pid:10506 tgid:10506 ppid:1      task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x16dc/0x5500 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7607
 rt_mutex_slowlock_block+0x55c/0x680 kernel/locking/rtmutex.c:1670
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1747 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1787 [inline]
 rt_mutex_slowlock+0x2d4/0x780 kernel/locking/rtmutex.c:1827
 __rt_mutex_lock kernel/locking/rtmutex.c:1842 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:560 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:578
 del_device_store+0xd6/0x370 drivers/net/netdevsim/bus.c:234
 kernfs_fop_write_iter+0x3a5/0x540 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x61e/0xbb0 fs/read_write.c:687
 ksys_write+0x156/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f923598e90e
RSP: 002b:00007ffda58dfb88 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00005555926a1500 RCX: 00007f923598e90e
RDX: 0000000000000001 RSI: 00007ffda58dfc10 RDI: 0000000000000005
RBP: 00007f9235a658a7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffda58dfc10 R14: 00007f9236784620 R15: 0000000000000003
 </TASK>
INFO: task syz-executor:10515 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:22968 pid:10515 tgid:10515 ppid:1      task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x16dc/0x5500 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7607
 rt_mutex_slowlock_block+0x55c/0x680 kernel/locking/rtmutex.c:1670
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1747 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1787 [inline]
 rt_mutex_slowlock+0x2d4/0x780 kernel/locking/rtmutex.c:1827
 __rt_mutex_lock kernel/locking/rtmutex.c:1842 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:560 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:578
 del_device_store+0xd6/0x370 drivers/net/netdevsim/bus.c:234
 kernfs_fop_write_iter+0x3a5/0x540 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x61e/0xbb0 fs/read_write.c:687
 ksys_write+0x156/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f049093e90e
RSP: 002b:00007fff48477bb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000055557c9a1500 RCX: 00007f049093e90e
RDX: 0000000000000001 RSI: 00007fff48477c40 RDI: 0000000000000005
RBP: 00007f0490a158a7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff48477c40 R14: 00007f0491734620 R15: 0000000000000003
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/38:
 #0: ffffffff8e1c3040 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8e1c3040 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffffffff8e1c3040 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by klogd/4942:
3 locks held by udevd/4953:
2 locks held by crond/5326:
3 locks held by kworker/0:5/5721:
3 locks held by kworker/0:7/6515:
2 locks held by kworker/1:8/8935:
7 locks held by kworker/u8:21/9601:
5 locks held by kworker/u8:36/9616:
9 locks held by kworker/u8:38/9618:
7 locks held by kworker/u8:39/9619:
6 locks held by kworker/u8:55/9635:
4 locks held by kworker/u8:99/9679:
2 locks held by kworker/u8:101/9681:
7 locks held by kworker/u8:109/9689:
5 locks held by kworker/u8:120/9700:
2 locks held by getty/9877:
 #0: ffff8880289350a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003bd32e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x460/0x1360 drivers/tty/n_tty.c:2211
5 locks held by syz-executor/10489:
 #0: ffff888035604500 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
 #0: ffff888035604500 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
 #1: ffff888033a1c478 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d9/0x540 fs/kernfs/file.c:336
 #2: ffff888028b8d1e8 (kn->active#51){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #2: ffff888028b8d1e8 (kn->active#51){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22c/0x540 fs/kernfs/file.c:337
 #3: ffffffff8ee21598 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd6/0x370 drivers/net/netdevsim/bus.c:234
 #4: ffff888031eeb160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #4: ffff888031eeb160 (&dev->mutex){....}-{4:4}, at: device_del+0xa9/0x8f0 drivers/base/core.c:3923
1 lock held by syz-executor/10497:
4 locks held by syz-executor/10506:
 #0: ffff888035604500 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
 #0: ffff888035604500 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
 #1: ffff88805163a078 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d9/0x540 fs/kernfs/file.c:336
 #2: ffff888028b8d1e8 (kn->active#51){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #2: ffff888028b8d1e8 (kn->active#51){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22c/0x540 fs/kernfs/file.c:337
 #3: ffffffff8ee21598 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd6/0x370 drivers/net/netdevsim/bus.c:234
4 locks held by syz-executor/10515:
 #0: ffff888035604500 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
 #0: ffff888035604500 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
 #1: ffff8880603d1878 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d9/0x540 fs/kernfs/file.c:336
 #2: ffff888028b8d1e8 (kn->active#51){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #2: ffff888028b8d1e8 (kn->active#51){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22c/0x540 fs/kernfs/file.c:337
 #3: ffffffff8ee21598 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd6/0x370 drivers/net/netdevsim/bus.c:234
8 locks held by syz.1.316/10968:
2 locks held by syz-executor/10971:
1 lock held by syz-executor/10975:
1 lock held by syz-executor/10977:
2 locks held by sed/10980:
5 locks held by syz-executor/10981:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:122
 nmi_trigger_cpumask_backtrace+0x17a/0x380 lib/nmi_backtrace.c:65
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0xfd7/0x1030 kernel/hung_task.c:561
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 10973 Comm: syz-executor Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:246 [inline]
RIP: 0010:__sanitizer_cov_trace_switch+0x7c/0x110 kernel/kcov.c:351
Code: 4c 8b 05 ef 90 d8 10 45 31 c9 41 ba 00 01 00 00 eb 0c 49 ff c1 4c 39 c8 0f 84 86 00 00 00 4e 8b 5c ce 10 65 8b 2d f4 90 d8 10 <81> e5 00 00 ff 00 41 8b 98 f4 0b 00 00 44 21 d3 41 89 de 41 09 ee
RSP: 0018:ffffc900059ef020 EFLAGS: 00000212
RAX: 0000000000000020 RBX: 0000000000000000 RCX: 0000000000000005
RDX: ffffffff81c9fb3a RSI: ffffffff8e2264f0 RDI: 000000000000000a
RBP: 0000000080000002 R08: ffff888030039f00 R09: 0000000000000004
R10: 0000000000000100 R11: 0000000000000004 R12: 000000c320f8770a
R13: 000000000000000a R14: 0000000000000000 R15: ffff88805778747c
FS:  0000000000000000(0000) GS:ffff888125d3a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000556a4a8ef178 CR3: 0000000037db8000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 rb_read_data_buffer+0x14a/0x5b0 kernel/trace/ring_buffer.c:1861
 check_buffer+0x288/0x7f0 kernel/trace/ring_buffer.c:4690
 __rb_reserve_next+0x537/0xdc0 kernel/trace/ring_buffer.c:4791
 rb_reserve_next_event kernel/trace/ring_buffer.c:4928 [inline]
 ring_buffer_lock_reserve+0xbd5/0x1040 kernel/trace/ring_buffer.c:4987
 __trace_buffer_lock_reserve kernel/trace/trace.h:1676 [inline]
 trace_event_buffer_lock_reserve+0x1d2/0x700 kernel/trace/trace.c:1924
 trace_event_buffer_reserve+0x1ef/0x2d0 kernel/trace/trace_events.c:688
 do_trace_event_raw_event_lock include/trace/events/lock.h:49 [inline]
 trace_event_raw_event_lock+0x126/0x280 include/trace/events/lock.h:49
 __do_trace_lock_release include/trace/events/lock.h:68 [inline]
 trace_lock_release include/trace/events/lock.h:68 [inline]
 lock_release+0x38e/0x3c0 kernel/locking/lockdep.c:5879
 rcu_lock_release include/linux/rcupdate.h:310 [inline]
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1183 [inline]
 unwind_next_frame+0x1baa/0x2550 arch/x86/kernel/unwind_orc.c:709
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 save_stack+0x124/0x230 mm/page_owner.c:165
 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1406 [inline]
 free_pages_prepare+0x946/0xa40 mm/page_alloc.c:1451
 __free_contig_range_common+0x174/0x340 mm/page_alloc.c:6897
 __free_contig_range mm/page_alloc.c:6942 [inline]
 free_pages_bulk+0x48/0x120 mm/page_alloc.c:5257
 vm_area_free_pages mm/vmalloc.c:3461 [inline]
 vfree+0x26f/0x510 mm/vmalloc.c:3510
 kcov_put kernel/kcov.c:449 [inline]
 kcov_close+0x2e/0x60 kernel/kcov.c:554
 __fput+0x42a/0xa80 fs/file_table.c:512
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x73a/0x2360 kernel/exit.c:1009
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
 get_signal+0x121b/0x12c0 kernel/signal.c:3046
 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop+0x104/0x750 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f975829de42
Code: Unable to access opcode bytes at 0x7f975829de18.
RSP: 002b:00007ffc7d4853d8 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: 00007f97574fb000 RBX: 00007f97574fb000 RCX: 00007f975829de42
RDX: 0000000000000003 RSI: 0000000000400000 RDI: 00007f97574fb000
RBP: 0000000000000011 R08: 00000000000000da R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000206 R12: 0000000000000003
R13: 0000000000000003 R14: 00007ffc7d485648 R15: 0000000000000000
 </TASK>