====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kworker/u4:8/3474 is trying to acquire lock: ffff8880b8e29370 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:2959 [inline] ffff8880b8e29370 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3368 [inline] ffff8880b8e29370 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3453 but task is already holding lock: ffff8880b8e29598 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x73b/0xdb0 kernel/time/timer.c:1112 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&base->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_timer_base+0x123/0x270 kernel/time/timer.c:999 __mod_timer+0xf9/0xdb0 kernel/time/timer.c:1080 queue_delayed_work_on+0x12a/0x1e0 kernel/workqueue.c:1987 kvfree_call_rcu+0x541/0x780 kernel/rcu/tree.c:3481 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:3796 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:1250 do_initcall_level+0x137/0x1f0 init/main.c:1312 do_initcalls+0x69/0xd0 init/main.c:1328 kernel_init_freeable+0x3d2/0x570 init/main.c:1565 kernel_init+0x1d/0x1c0 init/main.c:1455 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:2959 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3368 [inline] kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3453 trie_delete_elem+0x535/0x6a0 kernel/bpf/lpm_trie.c:545 bpf_prog_5186c38a4019a4cb+0x4a/0x4e bpf_dispatcher_nop_func include/linux/bpf.h:1224 [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_run3+0x1e7/0x400 kernel/trace/bpf_trace.c:2362 __bpf_trace_timer_start+0x14a/0x1b0 include/trace/events/timer.h:53 trace_timer_start include/trace/events/timer.h:53 [inline] enqueue_timer+0x398/0x530 kernel/time/timer.c:609 internal_add_timer kernel/time/timer.c:634 [inline] __mod_timer+0x977/0xdb0 kernel/time/timer.c:1131 queue_delayed_work_on+0x12a/0x1e0 kernel/workqueue.c:1987 queue_delayed_work include/linux/workqueue.h:577 [inline] srcu_funnel_gp_start kernel/rcu/srcutree.c:1066 [inline] srcu_gp_start_if_needed+0xcde/0x1140 kernel/rcu/srcutree.c:1292 rcu_do_batch kernel/rcu/tree.c:2194 [inline] rcu_core+0xcc4/0x1720 kernel/rcu/tree.c:2467 handle_softirqs+0x280/0x820 kernel/softirq.c:578 __do_softirq kernel/softirq.c:612 [inline] invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 __sanitizer_cov_trace_pc+0x8/0x60 kernel/kcov.c:212 __orc_find arch/x86/kernel/unwind_orc.c:99 [inline] orc_find arch/x86/kernel/unwind_orc.c:227 [inline] unwind_next_frame+0x4d9/0x2970 arch/x86/kernel/unwind_orc.c:494 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4e/0x70 mm/kasan/common.c:52 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:328 kasan_slab_alloc include/linux/kasan.h:188 [inline] slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767 slab_alloc_node mm/slub.c:3495 [inline] kmem_cache_alloc_node+0x150/0x330 mm/slub.c:3540 __alloc_skb+0x108/0x2c0 net/core/skbuff.c:640 alloc_skb include/linux/skbuff.h:1284 [inline] nlmsg_new include/net/netlink.h:1010 [inline] inet_netconf_notify_devconf+0x173/0x230 net/ipv4/devinet.c:2149 __devinet_sysctl_unregister net/ipv4/devinet.c:2660 [inline] devinet_sysctl_unregister net/ipv4/devinet.c:2684 [inline] inetdev_destroy net/ipv4/devinet.c:330 [inline] inetdev_event+0x789/0x15c0 net/ipv4/devinet.c:1636 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:11086 ip6gre_exit_batch_net+0x449/0x490 net/ipv6/ip6_gre.c:1647 ops_exit_list net/core/net_namespace.c:178 [inline] cleanup_net+0x77f/0xb90 net/core/net_namespace.c:652 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 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 *** 8 locks held by kworker/u4:8/3474: #0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711 #1: ffffc9000ca37d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #1: ffffc9000ca37d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711 #2: ffffffff8dfaee10 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x136/0xb90 net/core/net_namespace.c:606 #3: ffffffff8dfbbc48 (rtnl_mutex){+.+.}-{3:3}, at: ip6gre_exit_batch_net+0xc3/0x490 net/ipv6/ip6_gre.c:1644 #4: ffffffff8cd30040 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #4: ffffffff8cd30040 (rcu_callback){....}-{0:0}, at: rcu_do_batch kernel/rcu/tree.c:2188 [inline] #4: ffffffff8cd30040 (rcu_callback){....}-{0:0}, at: rcu_core+0xc51/0x1720 kernel/rcu/tree.c:2467 #5: ffffffff8cd78148 (tracepoint_srcu_srcu_usage.lock){....}-{2:2}, at: spin_lock_irqsave_ssp_contention+0xf0/0x440 kernel/rcu/srcutree.c:387 #6: ffff8880b8e29598 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x73b/0xdb0 kernel/time/timer.c:1112 #7: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #7: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #7: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2321 [inline] #7: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run3+0xf4/0x400 kernel/trace/bpf_trace.c:2362 stack backtrace: CPU: 0 PID: 3474 Comm: kworker/u4:8 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Workqueue: netns cleanup_net 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:2959 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3368 [inline] kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3453 trie_delete_elem+0x535/0x6a0 kernel/bpf/lpm_trie.c:545 bpf_prog_5186c38a4019a4cb+0x4a/0x4e bpf_dispatcher_nop_func include/linux/bpf.h:1224 [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_run3+0x1e7/0x400 kernel/trace/bpf_trace.c:2362 __bpf_trace_timer_start+0x14a/0x1b0 include/trace/events/timer.h:53 trace_timer_start include/trace/events/timer.h:53 [inline] enqueue_timer+0x398/0x530 kernel/time/timer.c:609 internal_add_timer kernel/time/timer.c:634 [inline] __mod_timer+0x977/0xdb0 kernel/time/timer.c:1131 queue_delayed_work_on+0x12a/0x1e0 kernel/workqueue.c:1987 queue_delayed_work include/linux/workqueue.h:577 [inline] srcu_funnel_gp_start kernel/rcu/srcutree.c:1066 [inline] srcu_gp_start_if_needed+0xcde/0x1140 kernel/rcu/srcutree.c:1292 rcu_do_batch kernel/rcu/tree.c:2194 [inline] rcu_core+0xcc4/0x1720 kernel/rcu/tree.c:2467 handle_softirqs+0x280/0x820 kernel/softirq.c:578 __do_softirq kernel/softirq.c:612 [inline] invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:get_current arch/x86/include/asm/current.h:41 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x60 kernel/kcov.c:215 Code: 00 00 f3 0f 1e fa 53 48 89 fb e8 13 00 00 00 48 8b 3d 0c fe c4 0c 48 89 de 5b e9 33 89 56 00 cc cc cc f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d 20 28 7e 7e 65 8b 15 21 28 7e 7e 81 e2 00 01 ff 00 74 RSP: 0018:ffffc9000ca37130 EFLAGS: 00000246 RAX: ffffffff813aa819 RBX: ffffffff8e5b5410 RCX: ffff88802d770000 RDX: 0000000000000000 RSI: ffffffff81592669 RDI: ffffffff815926fb RBP: ffffffff8e5b5410 R08: ffffc9000ca372d0 R09: 000000000000000d R10: 0000000000000004 R11: 0000000000000000 R12: ffffffff8e5b5410 R13: ffffffff815926fb R14: ffffffff81592669 R15: ffffffff8e5b5414 __orc_find arch/x86/kernel/unwind_orc.c:99 [inline] orc_find arch/x86/kernel/unwind_orc.c:227 [inline] unwind_next_frame+0x4d9/0x2970 arch/x86/kernel/unwind_orc.c:494 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4e/0x70 mm/kasan/common.c:52 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:328 kasan_slab_alloc include/linux/kasan.h:188 [inline] slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767 slab_alloc_node mm/slub.c:3495 [inline] kmem_cache_alloc_node+0x150/0x330 mm/slub.c:3540 __alloc_skb+0x108/0x2c0 net/core/skbuff.c:640 alloc_skb include/linux/skbuff.h:1284 [inline] nlmsg_new include/net/netlink.h:1010 [inline] inet_netconf_notify_devconf+0x173/0x230 net/ipv4/devinet.c:2149 __devinet_sysctl_unregister net/ipv4/devinet.c:2660 [inline] devinet_sysctl_unregister net/ipv4/devinet.c:2684 [inline] inetdev_destroy net/ipv4/devinet.c:330 [inline] inetdev_event+0x789/0x15c0 net/ipv4/devinet.c:1636 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:11086 ip6gre_exit_batch_net+0x449/0x490 net/ipv6/ip6_gre.c:1647 ops_exit_list net/core/net_namespace.c:178 [inline] cleanup_net+0x77f/0xb90 net/core/net_namespace.c:652 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 ---------------- Code disassembly (best guess): 0: 00 00 add %al,(%rax) 2: f3 0f 1e fa endbr64 6: 53 push %rbx 7: 48 89 fb mov %rdi,%rbx a: e8 13 00 00 00 call 0x22 f: 48 8b 3d 0c fe c4 0c mov 0xcc4fe0c(%rip),%rdi # 0xcc4fe22 16: 48 89 de mov %rbx,%rsi 19: 5b pop %rbx 1a: e9 33 89 56 00 jmp 0x568952 1f: cc int3 20: cc int3 21: cc int3 22: f3 0f 1e fa endbr64 26: 48 8b 04 24 mov (%rsp),%rax * 2a: 65 48 8b 0d 20 28 7e mov %gs:0x7e7e2820(%rip),%rcx # 0x7e7e2852 <-- trapping instruction 31: 7e 32: 65 8b 15 21 28 7e 7e mov %gs:0x7e7e2821(%rip),%edx # 0x7e7e285a 39: 81 e2 00 01 ff 00 and $0xff0100,%edx 3f: 74 .byte 0x74