syzbot

INFO: task syz.2.691:9971 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.691       state:D stack:24824 pid:9971  tgid:9970  ppid:9503   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0x147b/0x4f50 kernel/sched/core.c:6867
 __schedule_loop kernel/sched/core.c:6949 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:6964
 percpu_rwsem_wait+0x2f7/0x340 kernel/locking/percpu-rwsem.c:164
 __percpu_down_read+0xfc/0x140 kernel/locking/percpu-rwsem.c:180
 percpu_down_read_internal include/linux/percpu-rwsem.h:67 [inline]
 percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
 __sb_start_write include/linux/fs/super.h:19 [inline]
 sb_start_write+0x18e/0x1c0 include/linux/fs/super.h:125
 mnt_want_write+0x41/0x90 fs/namespace.c:499
 open_last_lookups fs/namei.c:4538 [inline]
 path_openat+0xafb/0x3e70 fs/namei.c:4793
 do_filp_open+0x22d/0x490 fs/namei.c:4823
 do_sys_openat2+0x12f/0x220 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1447
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f793d4dacb9
RSP: 002b:00007f793b736028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f793d755fa0 RCX: 00007f793d4dacb9
RDX: 000000000006b142 RSI: 0000200000004400 RDI: ffffffffffffff9c
RBP: 00007f793d548bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f793d756038 R14: 00007f793d755fa0 R15: 00007ffe1824e0b8
 </TASK>
INFO: task syz.2.691:9972 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.691       state:D stack:24952 pid:9972  tgid:9970  ppid:9503   task_flags:0x400140 flags:0x00080006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0x147b/0x4f50 kernel/sched/core.c:6867
 __schedule_loop kernel/sched/core.c:6949 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:6964
 percpu_rwsem_wait+0x2f7/0x340 kernel/locking/percpu-rwsem.c:164
 __percpu_down_read+0xfc/0x140 kernel/locking/percpu-rwsem.c:180
 percpu_down_read_internal include/linux/percpu-rwsem.h:67 [inline]
 percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
 __sb_start_write include/linux/fs/super.h:19 [inline]
 sb_start_write+0x18e/0x1c0 include/linux/fs/super.h:125
 mnt_want_write+0x41/0x90 fs/namespace.c:499
 open_last_lookups fs/namei.c:4538 [inline]
 path_openat+0xafb/0x3e70 fs/namei.c:4793
 do_filp_open+0x22d/0x490 fs/namei.c:4823
 do_sys_openat2+0x12f/0x220 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1447
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f793d4dacb9
RSP: 002b:00007f793b715028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f793d756090 RCX: 00007f793d4dacb9
RDX: 0000000000141842 RSI: 0000200000000440 RDI: ffffffffffffff9c
RBP: 00007f793d548bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f793d756128 R14: 00007f793d756090 R15: 00007ffe1824e0b8
 </TASK>
INFO: task syz.2.691:9973 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.691       state:D stack:28088 pid:9973  tgid:9970  ppid:9503   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0x147b/0x4f50 kernel/sched/core.c:6867
 __schedule_loop kernel/sched/core.c:6949 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:6964
 percpu_rwsem_wait+0x2f7/0x340 kernel/locking/percpu-rwsem.c:164
 __percpu_down_read+0xfc/0x140 kernel/locking/percpu-rwsem.c:180
 percpu_down_read_internal include/linux/percpu-rwsem.h:67 [inline]
 percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
 __sb_start_write include/linux/fs/super.h:19 [inline]
 sb_start_write+0x18e/0x1c0 include/linux/fs/super.h:125
 mnt_want_write+0x41/0x90 fs/namespace.c:499
 open_last_lookups fs/namei.c:4538 [inline]
 path_openat+0xafb/0x3e70 fs/namei.c:4793
 do_filp_open+0x22d/0x490 fs/namei.c:4823
 do_sys_openat2+0x12f/0x220 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_creat fs/open.c:1514 [inline]
 __se_sys_creat fs/open.c:1508 [inline]
 __x64_sys_creat+0x8f/0xc0 fs/open.c:1508
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f793d4dacb9
RSP: 002b:00007f793b6f4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007f793d756180 RCX: 00007f793d4dacb9
RDX: 0000000000000000 RSI: 0000000000000026 RDI: 0000200000000100
RBP: 00007f793d548bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f793d756218 R14: 00007f793d756180 R15: 00007ffe1824e0b8
 </TASK>

Showing all locks held in the system:
4 locks held by pr/legacy/17:
1 lock held by khungtaskd/38:
 #0: ffffffff8d9aea00 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8d9aea00 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8d9aea00 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:6/1041:
 #0: ffff888145af1938 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff888145af1938 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc90004b67bc0 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc90004b67bc0 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
2 locks held by dhcpcd/5464:
 #0: ffffffff8ec8c5d8 (vlan_ioctl_mutex){+.+.}-{4:4}, at: sock_ioctl+0x644/0x7f0 net/socket.c:1337
 #1: ffffffff8eca88b8 (rtnl_mutex){+.+.}-{4:4}, at: vlan_ioctl_handler+0xf0/0x630 net/8021q/vlan.c:579
2 locks held by getty/5560:
 #0: ffff88802716a0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
3 locks held by kworker/u8:26/7983:
 #0: ffff88813fe69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff88813fe69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc900055d7bc0 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc900055d7bc0 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
 #2: ffffffff8eca88b8 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:303
4 locks held by kworker/u8:27/8092:
1 lock held by syz.2.691/9971:
 #0: ffff88805e7c0480 (sb_writers#28){++++}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
1 lock held by syz.2.691/9972:
 #0: ffff88805e7c0480 (sb_writers#28){++++}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
1 lock held by syz.2.691/9973:
 #0: ffff88805e7c0480 (sb_writers#28){++++}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
2 locks held by udevd/10405:
 #0: ffff8880365d7670 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_downgrade include/linux/mmap_lock.h:385 [inline]
 #0: ffff8880365d7670 (&mm->mmap_lock){++++}-{4:4}, at: vms_complete_munmap_vmas+0x196/0x890 mm/vma.c:1313
 #1: ffff88801a6cc0f0 (&lruvec->lru_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:44 [inline]
 #1: ffff88801a6cc0f0 (&lruvec->lru_lock){+.+.}-{3:3}, at: folio_lruvec_lock_irqsave+0x126/0x1b0 mm/memcontrol.c:1256
2 locks held by syz-executor/11289:
 #0: ffffffff8f1b9180 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8f1b9180 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8f1b9180 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8eca88b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8eca88b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8eca88b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8a1/0x1be0 net/core/rtnetlink.c:4071
1 lock held by syz-executor/11419:
 #0: ffffffff8eca88b8 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x3bf/0x1e10 drivers/net/tun.c:3078
3 locks held by syz.0.861/11642:
1 lock held by syz.3.862/11650:
3 locks held by syz.4.865/11675:
3 locks held by udevadm/11665:

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

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 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [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:346 [inline]
 watchdog+0xf90/0xfe0 kernel/hung_task.c:515
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 8092 Comm: kworker/u8:27 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: netns cleanup_net
RIP: 0010:remove_class_from_lock_chain kernel/locking/lockdep.c:6197 [inline]
RIP: 0010:remove_class_from_lock_chains kernel/locking/lockdep.c:6236 [inline]
RIP: 0010:zap_class+0xcf/0x340 kernel/locking/lockdep.c:6281
Code: 49 81 fc 00 00 08 00 0f 84 a4 01 00 00 4e 8b 2c e5 c0 13 b8 92 4d 85 ed 0f 94 c0 49 83 c5 f8 0f 94 c1 08 c1 75 d7 45 8b 75 00 <41> f6 c6 fc 0f 84 e1 00 00 00 41 c1 ee 08 4a 8d 1c 75 90 13 fd 91
RSP: 0018:ffffc90005337540 EFLAGS: 00000097
RAX: 00000000000fa9f8 RBX: ffffffff921c6780 RCX: 00000000000fa9f2
RDX: ffffffff92b813b8 RSI: 0000000000000008 RDI: 000000000015a0af
RBP: ffffffff92fc1830 R08: ffffffff81ab53d8 R09: ffffffff8d9aea00
R10: dffffc0000000000 R11: fffffbfff1e36e0f R12: 000000000006c7b6
R13: ffffffff93050af0 R14: 00000000012e3914 R15: 00000000000011ef
FS:  0000000000000000(0000) GS:ffff8881269d9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 0000000040d6e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __lockdep_free_key_range kernel/locking/lockdep.c:6407 [inline]
 lockdep_unregister_key+0x1c3/0x350 kernel/locking/lockdep.c:6609
 __qdisc_destroy+0x166/0x3f0 net/sched/sch_generic.c:1079
 qdisc_put net/sched/sch_generic.c:1105 [inline]
 dev_shutdown+0x34c/0x440 net/sched/sch_generic.c:1493
 unregister_netdevice_many_notify+0x11a9/0x2360 net/core/dev.c:12384
 unregister_netdevice_many net/core/dev.c:12459 [inline]
 default_device_exit_batch+0x987/0xa10 net/core/dev.c:13051
 ops_exit_list net/core/net_namespace.c:205 [inline]
 ops_undo_list+0x52b/0x940 net/core/net_namespace.c:252
 cleanup_net+0x4e5/0x7b0 net/core/net_namespace.c:696
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340
 worker_thread+0x89f/0xd90 kernel/workqueue.c:3421
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>