============================================ WARNING: possible recursive locking detected 6.6.98-syzkaller #0 Not tainted -------------------------------------------- kworker/u4:1/12 is trying to acquire lock: ffff8880b8e295a8 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:2959 [inline] ffff8880b8e295a8 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3368 [inline] ffff8880b8e295a8 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3453 but task is already holding lock: ffff8880b8e295a8 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:2959 [inline] ffff8880b8e295a8 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3368 [inline] ffff8880b8e295a8 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3453 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(krc.lock); lock(krc.lock); *** DEADLOCK *** May be due to missing lock nesting notation 8 locks held by kworker/u4:1/12: #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: ffffc90000117d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #1: ffffc90000117d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711 #2: ffffffff8dfadc10 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x136/0xb90 net/core/net_namespace.c:606 #3: ffffffff8dfbaa08 (rtnl_mutex){+.+.}-{3:3}, at: ip_tunnel_delete_nets+0xcc/0x360 net/ipv4/ip_tunnel.c:1166 #4: ffffffff8ce938b8 (sysctl_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #4: ffffffff8ce938b8 (sysctl_lock){+.+.}-{2:2}, at: start_unregistering fs/proc/proc_sysctl.c:314 [inline] #4: ffffffff8ce938b8 (sysctl_lock){+.+.}-{2:2}, at: drop_sysctl_table+0x173/0x4b0 fs/proc/proc_sysctl.c:1507 #5: ffff8880b8e295a8 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:2959 [inline] #5: ffff8880b8e295a8 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3368 [inline] #5: ffff8880b8e295a8 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3453 #6: ffff8880b8e297d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:999 #7: ffffffff8cd2fae0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #7: ffffffff8cd2fae0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #7: ffffffff8cd2fae0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2321 [inline] #7: ffffffff8cd2fae0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run3+0xf4/0x400 kernel/trace/bpf_trace.c:2362 stack backtrace: CPU: 0 PID: 12 Comm: kworker/u4:1 Not tainted 6.6.98-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: netns cleanup_net Call Trace: dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106 check_deadlock kernel/locking/lockdep.c:3062 [inline] validate_chain kernel/locking/lockdep.c:3856 [inline] __lock_acquire+0x5d40/0x7c80 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_2c29ac5cdc6b1842+0x42/0x46 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_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 kvfree_call_rcu+0x541/0x780 kernel/rcu/tree.c:3481 drop_sysctl_table+0x356/0x4b0 fs/proc/proc_sysctl.c:1511 unregister_sysctl_table+0x41/0x60 fs/proc/proc_sysctl.c:1532 __devinet_sysctl_unregister net/ipv4/devinet.c:2657 [inline] devinet_sysctl_unregister net/ipv4/devinet.c:2685 [inline] inetdev_destroy net/ipv4/devinet.c:330 [inline] inetdev_event+0x760/0x15c0 net/ipv4/devinet.c:1637 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] 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