syzbot

INFO: task syz.0.2723:8820 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.2723      state:D stack:27560 pid:8820  ppid:8472   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 perf_pending_task_sync kernel/events/core.c:5244 [inline]
 _free_event+0x174/0xf30 kernel/events/core.c:5250
 put_event kernel/events/core.c:5378 [inline]
 perf_event_release_kernel+0x842/0x8d0 kernel/events/core.c:5503
 perf_release+0x3b/0x40 kernel/events/core.c:5513
 __fput+0x234/0x970 fs/file_table.c:384
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 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+0xee/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+0x61/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f87eb19cdd9
RSP: 002b:00007ffe538ec618 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffe538ec700 RCX: 00007f87eb19cdd9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000003f06f R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2d620000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f87eb415fac R14: 00007f87eb415fa8 R15: 00007f87eb415fa0
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u4:1/12:
 #0: ffff88801a254938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff88801a254938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #1: ffffc90000117d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc90000117d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #2: ffffffff8e3b57d0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x14c/0xbb0 net/core/net_namespace.c:606
 #3: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: default_device_exit_batch+0xf2/0xa80 net/core/dev.c:11644
1 lock held by rcu_preempt/17:
 #0: ffff8880b8f3c018 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559
1 lock held by khungtaskd/29:
 #0: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
3 locks held by kworker/u4:3/48:
2 locks held by kworker/0:2/788:
 #0: ffff888017c72538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff888017c72538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #1: ffffc90003a97d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc90003a97d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
3 locks held by kworker/u4:7/3421:
 #0: ffff888017c71538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff888017c71538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #1: ffffc9000c767d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc9000c767d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #2: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:286
2 locks held by getty/5527:
 #0: ffff88814c8330a0 (&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+0x433/0x1390 drivers/tty/n_tty.c:2217
3 locks held by kworker/1:3/5604:
 #0: ffff888017c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff888017c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #1: ffffc90003b37d00 (deferred_process_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc90003b37d00 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #2: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xe/0x20 net/switchdev/switchdev.c:104
7 locks held by syz-executor/11626:
 #0: ffff88802ca52418 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x21b/0x990 fs/read_write.c:580
 #1: ffff888021714088 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1e7/0x520 fs/kernfs/file.c:343
 #2: ffff888024310e90 (kn->active#60){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #2: ffff888024310e90 (kn->active#60){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x23a/0x520 fs/kernfs/file.c:344
 #3: ffffffff8dca2848 (nsim_bus_dev_list_lock){+.+.}-{3:3}, at: new_device_store+0x13d/0x690 drivers/net/netdevsim/bus.c:160
 #4: ffff8880322210e8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:995 [inline]
 #4: ffff8880322210e8 (&dev->mutex){....}-{3:3}, at: __device_attach+0x89/0x420 drivers/base/dd.c:1005
 #5: ffff88807ddba250 (&devlink->lock_key#13){+.+.}-{3:3}, at: nsim_drv_probe+0xc8/0xbb0 drivers/net/netdevsim/dev.c:1537
 #6: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: nsim_init_netdevsim drivers/net/netdevsim/netdev.c:335 [inline]
 #6: ffffffff8e3c2808 (rtnl_mutex){+.+.}-{3:3}, at: nsim_create+0x384/0x4a0 drivers/net/netdevsim/netdev.c:401

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a6/0x3e0 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+0xf3d/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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5124 Comm: klogd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:x64_sys_call+0x117f/0x2030 arch/x86/entry/syscall_64.c:29
Code: 00 81 fe f1 00 00 00 0f 84 ce ba de 02 81 fe f2 00 00 00 0f 84 52 be de 02 81 fe f3 00 00 00 0f 84 76 c2 de 02 e9 ac 0e 00 00 <83> fe 2a 0f 84 b8 0e 70 07 83 fe 2b 0f 84 9f 07 70 07 83 fe 2c 0f
RSP: 0018:ffffc900032b7f18 EFLAGS: 00000246
RAX: ffffffffffffffff RBX: ffffc900032b7f20 RCX: 00000000000001c6
RDX: dffffc0000000000 RSI: 000000000000002c RDI: ffffc900032b7f58
RBP: ffffc900032b7f48 R08: ffffffff8e8b15ef R09: 1ffffffff1d162bd
R10: dffffc0000000000 R11: fffffbfff1d162be R12: 0000000000000000
R13: 0000000000000000 R14: ffffc900032b7f58 R15: 000000000000002c
FS:  00007fd8e560ec80(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055aa5443f138 CR3: 000000002f6a1000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd8e575e407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffcbb42d4e0 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fd8e560ec80 RCX: 00007fd8e575e407
RDX: 000000000000003d RSI: 00007ffcbb42d620 RDI: 0000000000000003
RBP: 00007ffcbb42da50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004000 R11: 0000000000000202 R12: 00007ffcbb42da68
R13: 00007ffcbb42d620 R14: 0000000000000022 R15: 00007ffcbb42d620
 </TASK>