syzbot

INFO: task syz.0.17:6087 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:24744 pid:6087  tgid:6087  ppid:5990   task_flags:0x400040 flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5360 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
 __schedule_loop kernel/sched/core.c:7046 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7061
 request_wait_answer fs/fuse/dev.c:567 [inline]
 __fuse_request_send fs/fuse/dev.c:581 [inline]
 __fuse_simple_request+0xf15/0x18d0 fs/fuse/dev.c:675
 fuse_simple_request fs/fuse/fuse_i.h:1250 [inline]
 fuse_flush+0x5d4/0x800 fs/fuse/file.c:476
 filp_flush+0xbd/0x190 fs/open.c:1547
 filp_close+0x1d/0x40 fs/open.c:1560
 __range_close fs/file.c:767 [inline]
 __do_sys_close_range fs/file.c:826 [inline]
 __se_sys_close_range+0x359/0x650 fs/file.c:790
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1455b8ec29
RSP: 002b:00007ffed2027518 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: ffffffffffffffda RBX: 0000000000025134 RCX: 00007f1455b8ec29
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f1455dd7da0 R08: 0000000000000001 R09: 0000000dd202780f
R10: 0000001b32520000 R11: 0000000000000246 R12: 00007f1455dd5fac
R13: 00007f1455dd5fa0 R14: ffffffffffffffff R15: 00007ffed2027630
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/0:1/10:
 #0: ffff88813fe41948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
 #0: ffff88813fe41948 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
 #1: ffffc900000f7ba0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
 #1: ffffc900000f7ba0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
 #2: ffff8880296bf240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1f7/0x3b0 drivers/net/netdevsim/fib.c:1490
1 lock held by khungtaskd/31:
 #0: ffffffff8e53d260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e53d260 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e53d260 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5620:
 #0: ffff88814cc340a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222

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

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_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
 watchdog+0xf60/0xfa0 kernel/hung_task.c:495
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 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: 50 Comm: kworker/u8:3 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:validate_chain+0x2c4/0x2140 kernel/locking/lockdep.c:3920
Code: 00 00 83 3d 9d 09 47 0e 00 0f 84 a2 17 00 00 b8 01 00 00 00 65 48 8b 0d 3a de 49 11 48 3b 8c 24 d8 00 00 00 0f 85 43 1c 00 00 <48> 81 c4 e0 00 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d e9 96 82 f2 09
RSP: 0018:ffffc90000bb71b0 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000004 RCX: e96c1774642bf100
RDX: 0000000000000000 RSI: ffff888022aac850 RDI: ffff888022aabc80
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8173fd25
R10: ffffc90000bb7518 R11: ffffffff81ac9170 R12: 00000000cfd87156
R13: ffff888022aac7b0 R14: ffff888022aac850 R15: c0e1868fc470ad2d
FS:  0000000000000000(0000) GS:ffff8881257a2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f92c8602d58 CR3: 000000002d4a4000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 rcu_read_lock include/linux/rcupdate.h:841 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1169 [inline]
 unwind_next_frame+0xc2/0x2390 arch/x86/kernel/unwind_orc.c:479
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587
 kasan_save_free_info mm/kasan/kasan.h:406 [inline]
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2507 [inline]
 slab_free mm/slub.c:6557 [inline]
 kfree+0x19a/0x6d0 mm/slub.c:6765
 skb_release_data+0x62d/0x7c0 net/core/skbuff.c:1087
 skb_release_all net/core/skbuff.c:1152 [inline]
 __kfree_skb net/core/skbuff.c:1166 [inline]
 consume_skb+0x9e/0xf0 net/core/skbuff.c:1398
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:836 [inline]
 nsim_dev_trap_report_work+0x7cf/0xb80 drivers/net/netdevsim/dev.c:866
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>