====================================================== WARNING: possible circular locking dependency detected 6.6.94-syzkaller #0 Not tainted ------------------------------------------------------ syz.3.764/8976 is trying to acquire lock: ffff8880b8f295a8 (krc.lock){-.-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:2955 [inline] ffff8880b8f295a8 (krc.lock){-.-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3364 [inline] ffff8880b8f295a8 (krc.lock){-.-.}-{2:2}, at: kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3449 but task is already holding lock: ffff8880b8f2b958 (hrtimer_bases.lock){-.-.}-{2:2}, at: __run_hrtimer kernel/time/hrtimer.c:1759 [inline] ffff8880b8f2b958 (hrtimer_bases.lock){-.-.}-{2:2}, at: __hrtimer_run_queues+0x5e3/0xc40 kernel/time/hrtimer.c:1819 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (hrtimer_bases.lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162 lock_hrtimer_base kernel/time/hrtimer.c:181 [inline] hrtimer_start_range_ns+0xf3/0x1000 kernel/time/hrtimer.c:1354 hrtimer_start include/linux/hrtimer.h:421 [inline] run_page_cache_worker kernel/rcu/tree.c:3346 [inline] kvfree_call_rcu+0x5d5/0x780 kernel/rcu/tree.c:3451 rtnl_register_internal+0x486/0x590 net/core/rtnetlink.c:264 rtnl_register+0x32/0x70 net/core/rtnetlink.c:314 ip_rt_init+0x2ec/0x390 net/ipv4/route.c:3789 ip_init+0xe/0x20 net/ipv4/ip_output.c:1663 inet_init+0x2c1/0x3e0 net/ipv4/af_inet.c:2024 do_one_initcall+0x1fd/0x750 init/main.c:1238 do_initcall_level+0x137/0x1f0 init/main.c:1300 do_initcalls+0x69/0xd0 init/main.c:1316 kernel_init_freeable+0x3d2/0x570 init/main.c:1553 kernel_init+0x1d/0x1c0 init/main.c:1443 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 -> #0 (krc.lock){-.-.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __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:2955 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3364 [inline] kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3449 trie_delete_elem+0x535/0x6a0 kernel/bpf/lpm_trie.c:545 bpf_prog_5186c38a4019a4cb+0x4a/0x4e bpf_dispatcher_nop_func include/linux/bpf.h:1213 [inline] __bpf_prog_run include/linux/filter.h:612 [inline] bpf_prog_run include/linux/filter.h:619 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline] bpf_trace_run2+0x1d1/0x3c0 kernel/trace/bpf_trace.c:2361 __bpf_trace_hrtimer_start+0xfb/0x150 include/trace/events/timer.h:202 trace_hrtimer_start include/trace/events/timer.h:202 [inline] debug_activate kernel/time/hrtimer.c:506 [inline] enqueue_hrtimer+0x318/0x370 kernel/time/hrtimer.c:1113 __run_hrtimer kernel/time/hrtimer.c:1772 [inline] __hrtimer_run_queues+0x637/0xc40 kernel/time/hrtimer.c:1819 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1881 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline] __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 neigh_flush_dev+0x1f4/0xa80 net/core/neighbour.c:395 __neigh_ifdown+0x39/0x3f0 net/core/neighbour.c:446 neigh_ifdown+0x1f/0x30 net/core/neighbour.c:464 addrconf_ifdown+0x15ca/0x1880 net/ipv6/addrconf.c:3986 addrconf_notify+0x6c6/0x1010 net/ipv6/addrconf.c:-1 notifier_call_chain+0x197/0x390 kernel/notifier.c:93 call_netdevice_notifiers_extack net/core/dev.c:2064 [inline] call_netdevice_notifiers net/core/dev.c:2078 [inline] unregister_netdevice_many_notify+0xf36/0x1810 net/core/dev.c:11074 ip_tunnel_delete_nets+0x31c/0x360 net/ipv4/ip_tunnel.c:1171 ops_exit_list net/core/net_namespace.c:178 [inline] setup_net+0x83a/0xa00 net/core/net_namespace.c:375 copy_net_ns+0x36d/0x5e0 net/core/net_namespace.c:520 create_new_namespaces+0x3d3/0x6f0 kernel/nsproxy.c:110 copy_namespaces+0x430/0x4a0 kernel/nsproxy.c:179 copy_process+0x1700/0x3d70 kernel/fork.c:2509 kernel_clone+0x21b/0x840 kernel/fork.c:2914 __do_sys_clone kernel/fork.c:3057 [inline] __se_sys_clone kernel/fork.c:3041 [inline] __x64_sys_clone+0x18c/0x1e0 kernel/fork.c:3041 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(hrtimer_bases.lock); lock(krc.lock); lock(hrtimer_bases.lock); lock(krc.lock); *** DEADLOCK *** 5 locks held by syz.3.764/8976: #0: ffffffff8dfa1ed0 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x351/0x5e0 net/core/net_namespace.c:516 #1: ffffffff8dfaecc8 (rtnl_mutex){+.+.}-{3:3}, at: ip_tunnel_delete_nets+0xcc/0x360 net/ipv4/ip_tunnel.c:1166 #2: ffffffff8e0c2618 (&tbl->lock){+.-.}-{2:2}, at: __neigh_ifdown+0x2c/0x3f0 net/core/neighbour.c:445 #3: ffff8880b8f2b958 (hrtimer_bases.lock){-.-.}-{2:2}, at: __run_hrtimer kernel/time/hrtimer.c:1759 [inline] #3: ffff8880b8f2b958 (hrtimer_bases.lock){-.-.}-{2:2}, at: __hrtimer_run_queues+0x5e3/0xc40 kernel/time/hrtimer.c:1819 #4: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #4: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #4: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2321 [inline] #4: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xde/0x3c0 kernel/trace/bpf_trace.c:2361 stack backtrace: CPU: 1 PID: 8976 Comm: syz.3.764 Not tainted 6.6.94-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106 check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187 check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __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:2955 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3364 [inline] kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3449 trie_delete_elem+0x535/0x6a0 kernel/bpf/lpm_trie.c:545 bpf_prog_5186c38a4019a4cb+0x4a/0x4e bpf_dispatcher_nop_func include/linux/bpf.h:1213 [inline] __bpf_prog_run include/linux/filter.h:612 [inline] bpf_prog_run include/linux/filter.h:619 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline] bpf_trace_run2+0x1d1/0x3c0 kernel/trace/bpf_trace.c:2361 __bpf_trace_hrtimer_start+0xfb/0x150 include/trace/events/timer.h:202 trace_hrtimer_start include/trace/events/timer.h:202 [inline] debug_activate kernel/time/hrtimer.c:506 [inline] enqueue_hrtimer+0x318/0x370 kernel/time/hrtimer.c:1113 __run_hrtimer kernel/time/hrtimer.c:1772 [inline] __hrtimer_run_queues+0x637/0xc40 kernel/time/hrtimer.c:1819 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1881 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline] __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:neigh_flush_dev+0x1f4/0xa80 net/core/neighbour.c:395 Code: 22 9c 78 f9 4c 8b 2b 4d 85 ed 0f 84 f1 fe ff ff 48 83 7c 24 40 00 74 6e 49 8d 9d 08 03 00 00 48 89 d8 48 c1 e8 03 80 3c 28 00 <74> 08 48 89 df e8 f2 9b 78 f9 48 8b 44 24 40 48 39 03 0f 85 9f 07 RSP: 0018:ffffc90003897250 EFLAGS: 00000246 RAX: 1ffff1100ef37b61 RBX: ffff8880779bdb08 RCX: 0000000000080000 RDX: ffffc90014903000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000712e50 R12: ffff88802d24c380 R13: ffff8880779bd800 R14: 00000000000000ed R15: ffffffff8e0c2618 __neigh_ifdown+0x39/0x3f0 net/core/neighbour.c:446 neigh_ifdown+0x1f/0x30 net/core/neighbour.c:464 addrconf_ifdown+0x15ca/0x1880 net/ipv6/addrconf.c:3986 addrconf_notify+0x6c6/0x1010 net/ipv6/addrconf.c:-1 notifier_call_chain+0x197/0x390 kernel/notifier.c:93 call_netdevice_notifiers_extack net/core/dev.c:2064 [inline] call_netdevice_notifiers net/core/dev.c:2078 [inline] unregister_netdevice_many_notify+0xf36/0x1810 net/core/dev.c:11074 ip_tunnel_delete_nets+0x31c/0x360 net/ipv4/ip_tunnel.c:1171 ops_exit_list net/core/net_namespace.c:178 [inline] setup_net+0x83a/0xa00 net/core/net_namespace.c:375 copy_net_ns+0x36d/0x5e0 net/core/net_namespace.c:520 create_new_namespaces+0x3d3/0x6f0 kernel/nsproxy.c:110 copy_namespaces+0x430/0x4a0 kernel/nsproxy.c:179 copy_process+0x1700/0x3d70 kernel/fork.c:2509 kernel_clone+0x21b/0x840 kernel/fork.c:2914 __do_sys_clone kernel/fork.c:3057 [inline] __se_sys_clone kernel/fork.c:3041 [inline] __x64_sys_clone+0x18c/0x1e0 kernel/fork.c:3041 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f5b6218e929 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:00007f5b630defe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007f5b623b5fa0 RCX: 00007f5b6218e929 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000042164000 RBP: 00007f5b62210b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f5b623b5fa0 R15: 00007ffeb0a29c78 ---------------- Code disassembly (best guess): 0: 22 9c 78 f9 4c 8b 2b and 0x2b8b4cf9(%rax,%rdi,2),%bl 7: 4d 85 ed test %r13,%r13 a: 0f 84 f1 fe ff ff je 0xffffff01 10: 48 83 7c 24 40 00 cmpq $0x0,0x40(%rsp) 16: 74 6e je 0x86 18: 49 8d 9d 08 03 00 00 lea 0x308(%r13),%rbx 1f: 48 89 d8 mov %rbx,%rax 22: 48 c1 e8 03 shr $0x3,%rax 26: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1) * 2a: 74 08 je 0x34 <-- trapping instruction 2c: 48 89 df mov %rbx,%rdi 2f: e8 f2 9b 78 f9 call 0xf9789c26 34: 48 8b 44 24 40 mov 0x40(%rsp),%rax 39: 48 39 03 cmp %rax,(%rbx) 3c: 0f .byte 0xf 3d: 85 .byte 0x85 3e: 9f lahf 3f: 07 (bad)