====================================================== WARNING: possible circular locking dependency detected 5.15.180-syzkaller #0 Not tainted ------------------------------------------------------ kworker/1:3/4158 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: ffff88802537e1b8 (&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_1db1603a7cfa36fb+0x3d/0xa34 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 schedule_timeout+0x157/0x280 kernel/time/timer.c:1913 msleep+0x31/0x50 kernel/time/timer.c:2069 nsim_fib4_rt_add drivers/net/netdevsim/fib.c:367 [inline] nsim_fib4_rt_insert drivers/net/netdevsim/fib.c:430 [inline] nsim_fib4_event drivers/net/netdevsim/fib.c:462 [inline] nsim_fib_event drivers/net/netdevsim/fib.c:882 [inline] nsim_fib_event_work+0x19a6/0x3240 drivers/net/netdevsim/fib.c:1483 process_one_work+0x863/0x1000 kernel/workqueue.c:2310 process_scheduled_works kernel/workqueue.c:2373 [inline] worker_thread+0xdca/0x12a0 kernel/workqueue.c:2459 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_1db1603a7cfa36fb+0x3d/0xa34 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 schedule_timeout+0x157/0x280 kernel/time/timer.c:1913 msleep+0x31/0x50 kernel/time/timer.c:2069 nsim_fib4_rt_add drivers/net/netdevsim/fib.c:367 [inline] nsim_fib4_rt_insert drivers/net/netdevsim/fib.c:430 [inline] nsim_fib4_event drivers/net/netdevsim/fib.c:462 [inline] nsim_fib_event drivers/net/netdevsim/fib.c:882 [inline] nsim_fib_event_work+0x19a6/0x3240 drivers/net/netdevsim/fib.c:1483 process_one_work+0x863/0x1000 kernel/workqueue.c:2310 process_scheduled_works kernel/workqueue.c:2373 [inline] worker_thread+0xdca/0x12a0 kernel/workqueue.c:2459 kthread+0x436/0x520 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/1:3/4158: #0: ffff888016870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1 #1: ffffc90002dbfd00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285 #2: ffff888074219240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x271/0x3240 drivers/net/netdevsim/fib.c:1480 #3: ffff8880b9128098 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:946 #4: ffffffff8c11d9e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311 #5: ffff88802537e1b8 (&trie->lock){....}-{2:2}, at: trie_delete_elem+0x90/0x710 kernel/bpf/lpm_trie.c:467 stack backtrace: CPU: 1 PID: 4158 Comm: kworker/1:3 Not tainted 5.15.180-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Workqueue: events nsim_fib_event_work 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_1db1603a7cfa36fb+0x3d/0xa34 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 schedule_timeout+0x157/0x280 kernel/time/timer.c:1913 msleep+0x31/0x50 kernel/time/timer.c:2069 nsim_fib4_rt_add drivers/net/netdevsim/fib.c:367 [inline] nsim_fib4_rt_insert drivers/net/netdevsim/fib.c:430 [inline] nsim_fib4_event drivers/net/netdevsim/fib.c:462 [inline] nsim_fib_event drivers/net/netdevsim/fib.c:882 [inline] nsim_fib_event_work+0x19a6/0x3240 drivers/net/netdevsim/fib.c:1483 process_one_work+0x863/0x1000 kernel/workqueue.c:2310 process_scheduled_works kernel/workqueue.c:2373 [inline] worker_thread+0xdca/0x12a0 kernel/workqueue.c:2459 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287