====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kworker/1:5/4342 is trying to acquire lock: ffff8880b9127eb8 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3203 [inline] ffff8880b9127eb8 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3510 [inline] ffff8880b9127eb8 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x18d/0x7f0 kernel/rcu/tree.c:3601 but task is already holding lock: ffff88801f037238 (&trie->lock){....}-{2:2}, at: trie_delete_elem+0x8f/0x690 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+0xb0/0x100 kernel/locking/spinlock.c:162 trie_delete_elem+0x8f/0x690 kernel/bpf/lpm_trie.c:467 bpf_prog_41385012b43a9f2e+0x40/0x210 bpf_dispatcher_nop_func include/linux/bpf.h:888 [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 srcu_queue_delayed_work_on kernel/rcu/srcutree.c:470 [inline] srcu_schedule_cbs_sdp kernel/rcu/srcutree.c:479 [inline] srcu_schedule_cbs_snp kernel/rcu/srcutree.c:496 [inline] srcu_gp_end kernel/rcu/srcutree.c:555 [inline] srcu_advance_state kernel/rcu/srcutree.c:1231 [inline] process_srcu+0x695/0xca0 kernel/rcu/srcutree.c:1325 process_one_work+0x867/0xff0 kernel/workqueue.c:2310 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457 kthread+0x42e/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+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:3755 ip_init+0xa/0x20 net/ipv4/ip_output.c:1758 inet_init+0x28b/0x3a0 net/ipv4/af_inet.c:2007 do_one_initcall+0x272/0x730 init/main.c:1315 do_initcall_level+0x13d/0x1f0 init/main.c:1388 do_initcalls+0x4b/0x90 init/main.c:1404 kernel_init_freeable+0x3d5/0x560 init/main.c:1628 kernel_init+0x19/0x1b0 init/main.c:1519 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+0x2c66/0x7b50 kernel/locking/lockdep.c:5012 lock_acquire+0x19e/0x400 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: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_delete_elem+0x509/0x690 kernel/bpf/lpm_trie.c:540 bpf_prog_41385012b43a9f2e+0x40/0x210 bpf_dispatcher_nop_func include/linux/bpf.h:888 [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 srcu_queue_delayed_work_on kernel/rcu/srcutree.c:470 [inline] srcu_schedule_cbs_sdp kernel/rcu/srcutree.c:479 [inline] srcu_schedule_cbs_snp kernel/rcu/srcutree.c:496 [inline] srcu_gp_end kernel/rcu/srcutree.c:555 [inline] srcu_advance_state kernel/rcu/srcutree.c:1231 [inline] process_srcu+0x695/0xca0 kernel/rcu/srcutree.c:1325 process_one_work+0x867/0xff0 kernel/workqueue.c:2310 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 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 *** 6 locks held by kworker/1:5/4342: #0: ffff888016c72138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1 #1: ffffc90002fcfd00 ((work_completion)(&(&ssp->work)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285 #2: ffffffff8c35e810 (&ssp->srcu_cb_mutex){+.+.}-{3:3}, at: srcu_gp_end kernel/rcu/srcutree.c:523 [inline] #2: ffffffff8c35e810 (&ssp->srcu_cb_mutex){+.+.}-{3:3}, at: srcu_advance_state kernel/rcu/srcutree.c:1231 [inline] #2: ffffffff8c35e810 (&ssp->srcu_cb_mutex){+.+.}-{3:3}, at: process_srcu+0x1d1/0xca0 kernel/rcu/srcutree.c:1325 #3: ffff8880b91280d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:946 #4: ffffffff8c31ef20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312 #5: ffff88801f037238 (&trie->lock){....}-{2:2}, at: trie_delete_elem+0x8f/0x690 kernel/bpf/lpm_trie.c:467 stack backtrace: CPU: 1 PID: 4342 Comm: kworker/1:5 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: rcu_gp process_srcu 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: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: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_delete_elem+0x509/0x690 kernel/bpf/lpm_trie.c:540 bpf_prog_41385012b43a9f2e+0x40/0x210 bpf_dispatcher_nop_func include/linux/bpf.h:888 [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 srcu_queue_delayed_work_on kernel/rcu/srcutree.c:470 [inline] srcu_schedule_cbs_sdp kernel/rcu/srcutree.c:479 [inline] srcu_schedule_cbs_snp kernel/rcu/srcutree.c:496 [inline] srcu_gp_end kernel/rcu/srcutree.c:555 [inline] srcu_advance_state kernel/rcu/srcutree.c:1231 [inline] process_srcu+0x695/0xca0 kernel/rcu/srcutree.c:1325 process_one_work+0x867/0xff0 kernel/workqueue.c:2310 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287