syzbot

INFO: task syz.0.944:8784 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.944       state:D stack:23144 pid:8784  ppid:7779   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 perf_pending_task_sync kernel/events/core.c:5242 [inline]
 _free_event+0x174/0xf30 kernel/events/core.c:5248
 put_event kernel/events/core.c:5376 [inline]
 perf_event_release_kernel+0x836/0x8c0 kernel/events/core.c:5501
 perf_release+0x3b/0x40 kernel/events/core.c:5511
 __fput+0x234/0x970 fs/file_table.c:384
 task_work_run+0x1ce/0x250 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f2b6b58eba9
RSP: 002b:00007fff6aa675e8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 000000000004f88f RCX: 00007f2b6b58eba9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000001 R09: 000000036aa678df
R10: 0000001b32220000 R11: 0000000000000246 R12: 00007f2b6b7d5fac
R13: 00007f2b6b7d5fa0 R14: ffffffffffffffff R15: 0000000000000003
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2fe20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2fe20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2fe20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
3 locks held by kworker/u4:7/1084:
2 locks held by getty/5550:
 #0: ffff88802c9010a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000326e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
1 lock held by syz.3.1608/10853:
 #0: ffffffff8dfafad0 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x351/0x5e0 net/core/net_namespace.c:516

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

NMI backtrace for cpu 0
CPU: 0 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf41/0xf80 kernel/hung_task.c:379
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 9850 Comm: kworker/u4:0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:__trace_hardirqs_on_caller kernel/locking/lockdep.c:4299 [inline]
RIP: 0010:lockdep_hardirqs_on_prepare+0x2ed/0x760 kernel/locking/lockdep.c:4359
Code: 89 df e8 36 0f 76 00 48 ba 00 00 00 00 00 fc ff df eb 85 48 8b 44 24 10 4c 8d b8 c0 0a 00 00 4c 89 f8 48 c1 e8 03 0f b6 04 10 <84> c0 0f 85 3e 03 00 00 41 83 3f 00 0f 84 f5 00 00 00 41 0f b6 04
RSP: 0018:ffffc900053e7820 EFLAGS: 00000806
RAX: 0000000000000000 RBX: ffff88802e79a8d8 RCX: ffffffff8167bd44
RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffffffff90da75f0
RBP: ffffc900053e78d8 R08: ffffffff90da75f7 R09: 1ffffffff21b4ebe
R10: dffffc0000000000 R11: fffffbfff21b4ebf R12: ffff88802e79a9a0
R13: 0000000000000004 R14: 1ffff11005cf351b R15: ffff88802e79a8c0
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000002fd1a000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 trace_hardirqs_on+0x28/0x40 kernel/trace/trace_preemptirq.c:61
 ___slab_alloc+0x4e8/0x1300 mm/slub.c:3220
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc_node_track_caller+0xa2/0x230 mm/slab_common.c:1027
 kmalloc_reserve+0x117/0x260 net/core/skbuff.c:581
 __alloc_skb+0x138/0x2c0 net/core/skbuff.c:650
 alloc_skb include/linux/skbuff.h:1284 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
 nsim_dev_trap_report_work+0x293/0xb00 drivers/net/netdevsim/dev.c:851
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>