====================================================== WARNING: possible circular locking dependency detected 6.12.0-rc6-syzkaller-00169-g906bd684e4b1 #0 Not tainted ------------------------------------------------------ syz.0.3258/22008 is trying to acquire lock: ffff8880b8729430 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3312 [inline] ffff8880b8729430 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3725 [inline] ffff8880b8729430 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x18a/0x790 kernel/rcu/tree.c:3811 but task is already holding lock: ffff8880b872a718 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x112/0x240 kernel/time/timer.c:1051 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&base->lock){-.-.}-{2:2}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162 lock_timer_base+0x112/0x240 kernel/time/timer.c:1051 __mod_timer+0x1ca/0xeb0 kernel/time/timer.c:1132 queue_delayed_work_on+0x1ca/0x390 kernel/workqueue.c:2552 kvfree_call_rcu+0x47f/0x790 kernel/rcu/tree.c:3839 pwq_release_workfn+0x664/0x800 kernel/workqueue.c:5078 kthread_worker_fn+0x502/0xb70 kernel/kthread.c:844 kthread+0x2f2/0x390 kernel/kthread.c:389 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #0 (krc.lock){..-.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 krc_this_cpu_lock kernel/rcu/tree.c:3312 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3725 [inline] kvfree_call_rcu+0x18a/0x790 kernel/rcu/tree.c:3811 trie_delete_elem+0x546/0x6a0 kernel/bpf/lpm_trie.c:540 bpf_prog_2e5e7763945ac34e+0x45/0x4d bpf_dispatcher_nop_func include/linux/bpf.h:1265 [inline] __bpf_prog_run include/linux/filter.h:701 [inline] bpf_prog_run include/linux/filter.h:708 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2316 [inline] bpf_trace_run2+0x2ee/0x540 kernel/trace/bpf_trace.c:2357 __traceiter_timer_start+0x77/0xc0 include/trace/events/timer.h:52 trace_timer_start include/trace/events/timer.h:52 [inline] enqueue_timer+0x3ce/0x570 kernel/time/timer.c:663 internal_add_timer kernel/time/timer.c:688 [inline] __mod_timer+0xa0e/0xeb0 kernel/time/timer.c:1183 mrp_join_timer_arm net/802/mrp.c:597 [inline] mrp_join_timer+0x148/0x180 net/802/mrp.c:612 call_timer_fn+0x190/0x650 kernel/time/timer.c:1794 expire_timers kernel/time/timer.c:1845 [inline] __run_timers kernel/time/timer.c:2419 [inline] __run_timer_base+0x66a/0x8e0 kernel/time/timer.c:2430 run_timer_base kernel/time/timer.c:2439 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2449 handle_softirqs+0x2c7/0x980 kernel/softirq.c:554 __do_softirq kernel/softirq.c:588 [inline] invoke_softirq kernel/softirq.c:428 [inline] __irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637 irq_exit_rcu+0x9/0x30 kernel/softirq.c:649 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 lockdep_unregister_key+0x56d/0x610 kernel/locking/lockdep.c:6569 __qdisc_destroy+0x165/0x410 net/sched/sch_generic.c:1085 netdev_for_each_tx_queue include/linux/netdevice.h:2504 [inline] dev_shutdown+0x9b/0x450 net/sched/sch_generic.c:1496 unregister_netdevice_many_notify+0x995/0x1da0 net/core/dev.c:11396 unregister_netdevice_many net/core/dev.c:11469 [inline] unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11343 unregister_netdevice include/linux/netdevice.h:3118 [inline] __tun_detach+0x6b9/0x1600 drivers/net/tun.c:685 tun_detach drivers/net/tun.c:701 [inline] tun_chr_close+0x105/0x1b0 drivers/net/tun.c:3517 __fput+0x241/0x880 fs/file_table.c:431 task_work_run+0x251/0x310 kernel/task_work.c:239 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&base->lock); lock(krc.lock); lock(&base->lock); lock(krc.lock); *** DEADLOCK *** 5 locks held by syz.0.3258/22008: #0: ffffffff8fcd3948 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline] #0: ffffffff8fcd3948 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3b/0x1b0 drivers/net/tun.c:3517 #1: ffffc90000a18c00 ((&app->join_timer)){+.-.}-{0:0}, at: call_timer_fn+0xc0/0x650 kernel/time/timer.c:1791 #2: ffff88802a1700c8 (&app->lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #2: ffff88802a1700c8 (&app->lock){+.-.}-{2:2}, at: mrp_join_timer+0xce/0x180 net/802/mrp.c:610 #3: ffff8880b872a718 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x112/0x240 kernel/time/timer.c:1051 #4: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #4: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #4: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2315 [inline] #4: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x1fc/0x540 kernel/trace/bpf_trace.c:2357 stack backtrace: CPU: 1 UID: 0 PID: 22008 Comm: syz.0.3258 Not tainted 6.12.0-rc6-syzkaller-00169-g906bd684e4b1 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206 check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 krc_this_cpu_lock kernel/rcu/tree.c:3312 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3725 [inline] kvfree_call_rcu+0x18a/0x790 kernel/rcu/tree.c:3811 trie_delete_elem+0x546/0x6a0 kernel/bpf/lpm_trie.c:540 bpf_prog_2e5e7763945ac34e+0x45/0x4d bpf_dispatcher_nop_func include/linux/bpf.h:1265 [inline] __bpf_prog_run include/linux/filter.h:701 [inline] bpf_prog_run include/linux/filter.h:708 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2316 [inline] bpf_trace_run2+0x2ee/0x540 kernel/trace/bpf_trace.c:2357 __traceiter_timer_start+0x77/0xc0 include/trace/events/timer.h:52 trace_timer_start include/trace/events/timer.h:52 [inline] enqueue_timer+0x3ce/0x570 kernel/time/timer.c:663 internal_add_timer kernel/time/timer.c:688 [inline] __mod_timer+0xa0e/0xeb0 kernel/time/timer.c:1183 mrp_join_timer_arm net/802/mrp.c:597 [inline] mrp_join_timer+0x148/0x180 net/802/mrp.c:612 call_timer_fn+0x190/0x650 kernel/time/timer.c:1794 expire_timers kernel/time/timer.c:1845 [inline] __run_timers kernel/time/timer.c:2419 [inline] __run_timer_base+0x66a/0x8e0 kernel/time/timer.c:2430 run_timer_base kernel/time/timer.c:2439 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2449 handle_softirqs+0x2c7/0x980 kernel/softirq.c:554 __do_softirq kernel/softirq.c:588 [inline] invoke_softirq kernel/softirq.c:428 [inline] __irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637 irq_exit_rcu+0x9/0x30 kernel/softirq.c:649 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lockdep_unregister_key+0x56d/0x610 kernel/locking/lockdep.c:6569 Code: 27 94 48 c7 c6 30 9e 70 81 e8 1f 46 0a 00 e8 8a 5a 0a 00 e9 e5 fb ff ff e8 60 aa 56 0a 41 f7 c7 00 02 00 00 74 d0 fb 45 84 f6 <75> cf eb e0 90 0f 0b 90 45 31 f6 e9 62 ff ff ff 90 0f 0b 90 e9 a1 RSP: 0018:ffffc9000336f880 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: 1ffff9200066df18 RCX: ffffffff9a3d4903 RDX: 0000000000000001 RSI: ffffffff8c0ad7a0 RDI: ffffffff8c610960 RBP: ffffc9000336f958 R08: ffffffff94280d6f R09: 1ffffffff28501ad R10: dffffc0000000000 R11: fffffbfff28501ae R12: ffffc9000336f8c0 R13: 1ffff9200066df14 R14: 0000000000000000 R15: 0000000000000217 __qdisc_destroy+0x165/0x410 net/sched/sch_generic.c:1085 netdev_for_each_tx_queue include/linux/netdevice.h:2504 [inline] dev_shutdown+0x9b/0x450 net/sched/sch_generic.c:1496 unregister_netdevice_many_notify+0x995/0x1da0 net/core/dev.c:11396 unregister_netdevice_many net/core/dev.c:11469 [inline] unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11343 unregister_netdevice include/linux/netdevice.h:3118 [inline] __tun_detach+0x6b9/0x1600 drivers/net/tun.c:685 tun_detach drivers/net/tun.c:701 [inline] tun_chr_close+0x105/0x1b0 drivers/net/tun.c:3517 __fput+0x241/0x880 fs/file_table.c:431 task_work_run+0x251/0x310 kernel/task_work.c:239 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f68b257e719 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe2e71a308 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007f68b2737a80 RCX: 00007f68b257e719 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f68b2737a80 R08: 00007f68b2722000 R09: 00007ffe2e71a5ff R10: 00000000003ffd20 R11: 0000000000000246 R12: 000000000018d9d1 R13: 00007ffe2e71a410 R14: 0000000000000032 R15: ffffffffffffffff ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 94 xchg %eax,%esp 1: 48 c7 c6 30 9e 70 81 mov $0xffffffff81709e30,%rsi 8: e8 1f 46 0a 00 call 0xa462c d: e8 8a 5a 0a 00 call 0xa5a9c 12: e9 e5 fb ff ff jmp 0xfffffbfc 17: e8 60 aa 56 0a call 0xa56aa7c 1c: 41 f7 c7 00 02 00 00 test $0x200,%r15d 23: 74 d0 je 0xfffffff5 25: fb sti 26: 45 84 f6 test %r14b,%r14b * 29: 75 cf jne 0xfffffffa <-- trapping instruction 2b: eb e0 jmp 0xd 2d: 90 nop 2e: 0f 0b ud2 30: 90 nop 31: 45 31 f6 xor %r14d,%r14d 34: e9 62 ff ff ff jmp 0xffffff9b 39: 90 nop 3a: 0f 0b ud2 3c: 90 nop 3d: e9 .byte 0xe9 3e: a1 .byte 0xa1