====================================================== WARNING: possible circular locking dependency detected 6.9.0-syzkaller-09429-g61307b7be41a #0 Not tainted ------------------------------------------------------ rcu_preempt/17 is trying to acquire lock: ffff8880b9529430 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3298 [inline] ffff8880b9529430 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3697 [inline] ffff8880b9529430 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x18a/0x790 kernel/rcu/tree.c:3782 but task is already holding lock: ffff8880b952a718 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x112/0x240 kernel/time/timer.c:1051 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&base->lock){-.-.}-{2:2}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162 lock_timer_base+0x112/0x240 kernel/time/timer.c:1051 __mod_timer+0x1ca/0xeb0 kernel/time/timer.c:1132 queue_delayed_work_on+0x1ca/0x390 kernel/workqueue.c:2572 kvfree_call_rcu+0x47f/0x790 kernel/rcu/tree.c:3810 rtnl_register_internal+0x482/0x590 net/core/rtnetlink.c:265 rtnl_register+0x36/0x80 net/core/rtnetlink.c:315 ip_rt_init+0x2fc/0x3a0 net/ipv4/route.c:3702 ip_init+0xe/0x20 net/ipv4/ip_output.c:1663 inet_init+0x3d8/0x580 net/ipv4/af_inet.c:1981 do_one_initcall+0x248/0x880 init/main.c:1248 do_initcall_level+0x157/0x210 init/main.c:1310 do_initcalls+0x3f/0x80 init/main.c:1326 kernel_init_freeable+0x435/0x5d0 init/main.c:1559 kernel_init+0x1d/0x2b0 init/main.c:1448 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #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+0x18cb/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1ed/0x550 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:3298 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3697 [inline] kvfree_call_rcu+0x18a/0x790 kernel/rcu/tree.c:3782 trie_delete_elem+0x546/0x6a0 kernel/bpf/lpm_trie.c:540 bpf_prog_41385012b43a9f2e+0x48/0x4c bpf_dispatcher_nop_func include/linux/bpf.h:1243 [inline] __bpf_prog_run include/linux/filter.h:691 [inline] bpf_prog_run include/linux/filter.h:698 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2403 [inline] bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2444 __traceiter_timer_start+0x75/0xc0 include/trace/events/timer.h:52 trace_timer_start include/trace/events/timer.h:52 [inline] enqueue_timer+0x3ce/0x570 kernel/time/timer.c:663 internal_add_timer kernel/time/timer.c:688 [inline] __mod_timer+0xa0e/0xeb0 kernel/time/timer.c:1183 schedule_timeout+0x1b9/0x310 kernel/time/timer.c:2580 rcu_gp_fqs_loop+0x2df/0x1370 kernel/rcu/tree.c:2000 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2202 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 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 *** 2 locks held by rcu_preempt/17: #0: ffff8880b952a718 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x112/0x240 kernel/time/timer.c:1051 #1: ffffffff8e333d20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline] #1: ffffffff8e333d20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline] #1: ffffffff8e333d20 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2402 [inline] #1: ffffffff8e333d20 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x1fc/0x540 kernel/trace/bpf_trace.c:2444 stack backtrace: CPU: 1 PID: 17 Comm: rcu_preempt Not tainted 6.9.0-syzkaller-09429-g61307b7be41a #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 check_noncircular+0x36a/0x4a0 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+0x18cb/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1ed/0x550 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:3298 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3697 [inline] kvfree_call_rcu+0x18a/0x790 kernel/rcu/tree.c:3782 trie_delete_elem+0x546/0x6a0 kernel/bpf/lpm_trie.c:540 bpf_prog_41385012b43a9f2e+0x48/0x4c bpf_dispatcher_nop_func include/linux/bpf.h:1243 [inline] __bpf_prog_run include/linux/filter.h:691 [inline] bpf_prog_run include/linux/filter.h:698 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2403 [inline] bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2444 __traceiter_timer_start+0x75/0xc0 include/trace/events/timer.h:52 trace_timer_start include/trace/events/timer.h:52 [inline] enqueue_timer+0x3ce/0x570 kernel/time/timer.c:663 internal_add_timer kernel/time/timer.c:688 [inline] __mod_timer+0xa0e/0xeb0 kernel/time/timer.c:1183 schedule_timeout+0x1b9/0x310 kernel/time/timer.c:2580 rcu_gp_fqs_loop+0x2df/0x1370 kernel/rcu/tree.c:2000 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2202 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244