====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.39/5053 is trying to acquire lock: ffff88807be69a38 (&trie->lock){..-.}-{2:2}, at: trie_delete_elem+0x8e/0x620 kernel/bpf/lpm_trie.c:466 but task is already holding lock: ffff8880b90280d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:946 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&base->lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162 lock_timer_base+0x123/0x270 kernel/time/timer.c:946 __mod_timer+0xf9/0xd20 kernel/time/timer.c:1027 queue_delayed_work_on+0x12d/0x1f0 kernel/workqueue.c:1715 queue_delayed_work include/linux/workqueue.h:527 [inline] schedule_delayed_work include/linux/workqueue.h:631 [inline] kvfree_call_rcu+0x4d6/0x7f0 kernel/rcu/tree.c:3629 rtnl_register_internal+0x485/0x590 net/core/rtnetlink.c:225 rtnl_register+0x2e/0x70 net/core/rtnetlink.c:275 ip_rt_init+0x2e3/0x3a0 net/ipv4/route.c:3784 ip_init+0xa/0x20 net/ipv4/ip_output.c:1762 inet_init+0x28b/0x3a0 net/ipv4/af_inet.c:2007 do_one_initcall+0x272/0x730 init/main.c:1276 do_initcall_level+0x13d/0x1f0 init/main.c:1349 do_initcalls+0x4b/0x90 init/main.c:1365 kernel_init_freeable+0x3d5/0x560 init/main.c:1589 kernel_init+0x19/0x1b0 init/main.c:1480 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 -> #1 (krc.lock){..-.}-{2:2}: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 krc_this_cpu_lock kernel/rcu/tree.c:3203 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3510 [inline] kvfree_call_rcu+0x18d/0x7f0 kernel/rcu/tree.c:3601 trie_update_elem+0x858/0xc10 kernel/bpf/lpm_trie.c:395 bpf_map_update_value+0x57c/0x650 kernel/bpf/syscall.c:223 generic_map_update_batch+0x52c/0x7d0 kernel/bpf/syscall.c:1430 bpf_map_do_batch+0x475/0x5f0 kernel/bpf/syscall.c:-1 __sys_bpf+0x671/0x6f0 kernel/bpf/syscall.c:-1 __do_sys_bpf kernel/bpf/syscall.c:4761 [inline] __se_sys_bpf kernel/bpf/syscall.c:4759 [inline] __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4759 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #0 (&trie->lock){..-.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5625 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162 trie_delete_elem+0x8e/0x620 kernel/bpf/lpm_trie.c:466 bpf_prog_5186c38a4019a4cb+0x42/0x8a8 bpf_dispatcher_nop_func include/linux/bpf.h:890 [inline] __bpf_prog_run include/linux/filter.h:628 [inline] bpf_prog_run include/linux/filter.h:635 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:1878 [inline] bpf_trace_run3+0x19e/0x350 kernel/trace/bpf_trace.c:1916 trace_timer_start include/trace/events/timer.h:52 [inline] enqueue_timer+0x394/0x520 kernel/time/timer.c:586 internal_add_timer kernel/time/timer.c:611 [inline] __mod_timer+0x918/0xd20 kernel/time/timer.c:1078 dsp_cmx_send+0x1a99/0x1b20 drivers/isdn/mISDN/dsp_cmx.c:1850 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648 expire_timers kernel/time/timer.c:1699 [inline] __run_timers+0x56c/0x810 kernel/time/timer.c:1970 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983 handle_softirqs+0x336/0x830 kernel/softirq.c:576 __do_softirq kernel/softirq.c:610 [inline] invoke_softirq kernel/softirq.c:450 [inline] __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 other info that might help us debug this: Chain exists of: &trie->lock --> krc.lock --> &base->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&base->lock); lock(krc.lock); lock(&base->lock); lock(&trie->lock); *** DEADLOCK *** 4 locks held by syz.0.39/5053: #0: ffffc9000121fb20 ((&dsp_spl_tl)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline] #0: ffffc9000121fb20 ((&dsp_spl_tl)){+.-.}-{0:0}, at: call_timer_fn+0xca/0x540 kernel/time/timer.c:1638 #1: ffffffff8d1f5cf8 (dsp_lock){..-.}-{2:2}, at: dsp_cmx_send+0x22/0x1b20 drivers/isdn/mISDN/dsp_cmx.c:1643 #2: ffff8880b90280d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:946 #3: ffffffff8c31ef60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312 stack backtrace: CPU: 0 PID: 5053 Comm: syz.0.39 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133 check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5625 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162 trie_delete_elem+0x8e/0x620 kernel/bpf/lpm_trie.c:466 bpf_prog_5186c38a4019a4cb+0x42/0x8a8 bpf_dispatcher_nop_func include/linux/bpf.h:890 [inline] __bpf_prog_run include/linux/filter.h:628 [inline] bpf_prog_run include/linux/filter.h:635 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:1878 [inline] bpf_trace_run3+0x19e/0x350 kernel/trace/bpf_trace.c:1916 trace_timer_start include/trace/events/timer.h:52 [inline] enqueue_timer+0x394/0x520 kernel/time/timer.c:586 internal_add_timer kernel/time/timer.c:611 [inline] __mod_timer+0x918/0xd20 kernel/time/timer.c:1078 dsp_cmx_send+0x1a99/0x1b20 drivers/isdn/mISDN/dsp_cmx.c:1850 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648 expire_timers kernel/time/timer.c:1699 [inline] __run_timers+0x56c/0x810 kernel/time/timer.c:1970 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983 handle_softirqs+0x336/0x830 kernel/softirq.c:576 __do_softirq kernel/softirq.c:610 [inline] invoke_softirq kernel/softirq.c:450 [inline] __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0033:0x7fc2d99a8679 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc2d900c028 EFLAGS: 00000246 RAX: 0000000000000005 RBX: 00007fc2d9c13fa0 RCX: 00007fc2d99a8679 RDX: 0000000000000018 RSI: 00002000000002c0 RDI: 0000000000000011 RBP: 00007fc2d9a3bee0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc2d9c14038 R14: 00007fc2d9c13fa0 R15: 00007ffe31c2d8f8