====================================================== WARNING: possible circular locking dependency detected 5.15.185-syzkaller #0 Not tainted ------------------------------------------------------ syz.2.93/4554 is trying to acquire lock: ffff8880b9127e78 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3199 [inline] ffff8880b9127e78 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3506 [inline] ffff8880b9127e78 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x186/0x7c0 kernel/rcu/tree.c:3597 but task is already holding lock: ffff88806139b5b8 (&trie->lock){..-.}-{2:2}, at: trie_delete_elem+0x90/0x710 kernel/bpf/lpm_trie.c:467 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&trie->lock){..-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 trie_delete_elem+0x90/0x710 kernel/bpf/lpm_trie.c:467 bpf_prog_63d1fe5ed215ff41+0xe00/0xf30 bpf_dispatcher_nop_func include/linux/bpf.h:790 [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+0x17e/0x320 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+0x8e1/0xd20 kernel/time/timer.c:1062 addrconf_mod_rs_timer net/ipv6/addrconf.c:328 [inline] addrconf_dad_completed+0x918/0xca0 net/ipv6/addrconf.c:4289 addrconf_dad_work+0xc70/0x1520 net/ipv6/addrconf.c:-1 process_one_work+0x863/0x1000 kernel/workqueue.c:2310 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 -> #1 (&base->lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 lock_timer_base+0x123/0x270 kernel/time/timer.c:946 __mod_timer+0x117/0xd20 kernel/time/timer.c:1019 queue_delayed_work_on+0x126/0x1e0 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+0x4a9/0x7c0 kernel/rcu/tree.c:3625 rtnl_register_internal+0x44e/0x540 net/core/rtnetlink.c:223 rtnl_register+0x2e/0x70 net/core/rtnetlink.c:273 ip_rt_init+0x2e0/0x3a0 net/ipv4/route.c:3791 ip_init+0xa/0x20 net/ipv4/ip_output.c:1749 inet_init+0x28b/0x3a0 net/ipv4/af_inet.c:2007 do_one_initcall+0x1ee/0x680 init/main.c:1302 do_initcall_level+0x137/0x1f0 init/main.c:1375 do_initcalls+0x4b/0x90 init/main.c:1391 kernel_init_freeable+0x3ce/0x560 init/main.c:1615 kernel_init+0x19/0x1b0 init/main.c:1506 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 -> #0 (krc.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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623 __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:3199 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3506 [inline] kvfree_call_rcu+0x186/0x7c0 kernel/rcu/tree.c:3597 trie_delete_elem+0x58c/0x710 kernel/bpf/lpm_trie.c:-1 bpf_prog_8c8ab8634bca3061+0x3a/0x99c bpf_dispatcher_nop_func include/linux/bpf.h:790 [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+0x17e/0x320 kernel/trace/bpf_trace.c:1916 __bpf_trace_kmem_cache_free+0x99/0xc0 include/trace/events/kmem.h:138 trace_kmem_cache_free include/trace/events/kmem.h:138 [inline] kmem_cache_free+0x1e7/0x210 mm/slub.c:3516 rcu_do_batch kernel/rcu/tree.c:2523 [inline] rcu_core+0x962/0x15d0 kernel/rcu/tree.c:2763 handle_softirqs+0x328/0x820 kernel/softirq.c:576 __do_softirq kernel/softirq.c:610 [inline] invoke_softirq kernel/softirq.c:450 [inline] __irq_exit_rcu+0x12f/0x220 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+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 finish_lock_switch+0x134/0x280 kernel/sched/core.c:4785 finish_task_switch+0x12f/0x640 kernel/sched/core.c:4902 context_switch kernel/sched/core.c:5033 [inline] __schedule+0x11c0/0x43b0 kernel/sched/core.c:6376 schedule+0x11b/0x1e0 kernel/sched/core.c:6459 freezable_schedule include/linux/freezer.h:172 [inline] do_nanosleep+0x1f1/0x760 kernel/time/hrtimer.c:2049 hrtimer_nanosleep+0x2f7/0x520 kernel/time/hrtimer.c:2102 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1314 [inline] __se_sys_clock_nanosleep+0x2e6/0x370 kernel/time/posix-timers.c:1291 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 other info that might help us debug this: Chain exists of: krc.lock --> &base->lock --> &trie->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&trie->lock); lock(&base->lock); lock(&trie->lock); lock(krc.lock); *** DEADLOCK *** 3 locks held by syz.2.93/4554: #0: ffffffff8c11c0c0 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x0/0x20 #1: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311 #2: ffff88806139b5b8 (&trie->lock){..-.}-{2:2}, at: trie_delete_elem+0x90/0x710 kernel/bpf/lpm_trie.c:467 stack backtrace: CPU: 1 PID: 4554 Comm: syz.2.93 Not tainted 5.15.185-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106 check_noncircular+0x274/0x310 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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623 __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:3199 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3506 [inline] kvfree_call_rcu+0x186/0x7c0 kernel/rcu/tree.c:3597 trie_delete_elem+0x58c/0x710 kernel/bpf/lpm_trie.c:-1 bpf_prog_8c8ab8634bca3061+0x3a/0x99c bpf_dispatcher_nop_func include/linux/bpf.h:790 [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+0x17e/0x320 kernel/trace/bpf_trace.c:1916 __bpf_trace_kmem_cache_free+0x99/0xc0 include/trace/events/kmem.h:138 trace_kmem_cache_free include/trace/events/kmem.h:138 [inline] kmem_cache_free+0x1e7/0x210 mm/slub.c:3516 rcu_do_batch kernel/rcu/tree.c:2523 [inline] rcu_core+0x962/0x15d0 kernel/rcu/tree.c:2763 handle_softirqs+0x328/0x820 kernel/softirq.c:576 __do_softirq kernel/softirq.c:610 [inline] invoke_softirq kernel/softirq.c:450 [inline] __irq_exit_rcu+0x12f/0x220 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+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:finish_lock_switch+0x134/0x280 kernel/sched/core.c:4785 Code: be ff ff ff ff e8 2c 0e 4e 08 85 c0 74 4a 4d 85 ff 75 66 0f 1f 44 00 00 48 89 df e8 26 6a 57 08 e8 21 7f 2a 00 fb 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 99 10 fe ff 43 80 3c RSP: 0018:ffffc900032df968 EFLAGS: 00000282 RAX: ab6b97d0b18d4c00 RBX: ffff8880b913a300 RCX: ab6b97d0b18d4c00 RDX: dffffc0000000000 RSI: ffffffff8a0b11c0 RDI: ffffffff8a59a740 RBP: 1ffff1101722760b R08: dffffc0000000000 R09: ffffed1017227461 R10: ffffed1017227461 R11: 1ffff11017227460 R12: 1ffff110172275b9 R13: dffffc0000000000 R14: ffff8880b913adc8 R15: 0000000000000000 finish_task_switch+0x12f/0x640 kernel/sched/core.c:4902 context_switch kernel/sched/core.c:5033 [inline] __schedule+0x11c0/0x43b0 kernel/sched/core.c:6376 schedule+0x11b/0x1e0 kernel/sched/core.c:6459 freezable_schedule include/linux/freezer.h:172 [inline] do_nanosleep+0x1f1/0x760 kernel/time/hrtimer.c:2049 hrtimer_nanosleep+0x2f7/0x520 kernel/time/hrtimer.c:2102 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1314 [inline] __se_sys_clock_nanosleep+0x2e6/0x370 kernel/time/posix-timers.c:1291 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 RIP: 0033:0x7faefed171e5 Code: 24 0c 89 3c 24 48 89 4c 24 18 e8 f6 54 ff ff 4c 8b 54 24 18 48 8b 54 24 10 41 89 c0 8b 74 24 0c 8b 3c 24 b8 e6 00 00 00 0f 05 <44> 89 c7 48 89 04 24 e8 4f 55 ff ff 48 8b 04 24 48 83 c4 28 f7 d8 RSP: 002b:00007ffd9c80b570 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6 RAX: ffffffffffffffda RBX: 00007faefef0bfa0 RCX: 00007faefed171e5 RDX: 00007ffd9c80b5b0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007faefef0dba0 R08: 0000000000000000 R09: 0015cdb716dfc898 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000015173 R13: 00007ffd9c80b6d0 R14: ffffffffffffffff R15: 00007ffd9c80b6f0 ---------------- Code disassembly (best guess): 0: be ff ff ff ff mov $0xffffffff,%esi 5: e8 2c 0e 4e 08 call 0x84e0e36 a: 85 c0 test %eax,%eax c: 74 4a je 0x58 e: 4d 85 ff test %r15,%r15 11: 75 66 jne 0x79 13: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 18: 48 89 df mov %rbx,%rdi 1b: e8 26 6a 57 08 call 0x8576a46 20: e8 21 7f 2a 00 call 0x2a7f46 25: fb sti 26: 48 83 c4 08 add $0x8,%rsp * 2a: 5b pop %rbx <-- trapping instruction 2b: 41 5c pop %r12 2d: 41 5d pop %r13 2f: 41 5e pop %r14 31: 41 5f pop %r15 33: 5d pop %rbp 34: c3 ret 35: 48 89 df mov %rbx,%rdi 38: e8 99 10 fe ff call 0xfffe10d6 3d: 43 rex.XB 3e: 80 .byte 0x80 3f: 3c .byte 0x3c