syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.22/4324 is trying to acquire lock:
ffff8880b9027eb8 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3203 [inline]
ffff8880b9027eb8 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3510 [inline]
ffff8880b9027eb8 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x186/0x7c0 kernel/rcu/tree.c:3601

but task is already holding lock:
ffff88807d446238 (&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_41385012b43a9f2e+0x40/0x4c
       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+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
       dsp_cmx_send+0x1ab4/0x1b30 drivers/isdn/mISDN/dsp_cmx.c:1850
       call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
       expire_timers kernel/time/timer.c:1496 [inline]
       __run_timers+0x525/0x7c0 kernel/time/timer.c:1767
       run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
       handle_softirqs+0x328/0x820 kernel/softirq.c:576
       __do_softirq kernel/softirq.c:610 [inline]
       invoke_softirq kernel/softirq.c:450 [inline]
       __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
       irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
       instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
       sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
       asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
       __text_poke+0x646/0x7b0 arch/x86/kernel/alternative.c:1389
       text_poke arch/x86/kernel/alternative.c:1413 [inline]
       text_poke_bp_batch+0x417/0x7c0 arch/x86/kernel/alternative.c:1664
       text_poke_flush arch/x86/kernel/alternative.c:1833 [inline]
       text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1840
       arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
       static_key_enable_cpuslocked+0x11f/0x240 kernel/jump_label.c:177
       static_key_enable+0x16/0x20 kernel/jump_label.c:190
       tracepoint_add_func+0x83b/0x9a0 kernel/tracepoint.c:361
       tracepoint_probe_register_prio_may_exist+0x5c/0x90 kernel/tracepoint.c:482
       bpf_raw_tracepoint_open+0x69d/0x780 kernel/bpf/syscall.c:3119
       __sys_bpf+0x48b/0x670 kernel/bpf/syscall.c:4699
       __do_sys_bpf kernel/bpf/syscall.c:4761 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:4759 [inline]
       __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4759
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #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:3629
       rtnl_register_internal+0x489/0x590 net/core/rtnetlink.c:225
       rtnl_register+0x2e/0x70 net/core/rtnetlink.c:275
       ip_rt_init+0x2e0/0x3a0 net/ipv4/route.c:3803
       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:1316
       do_initcall_level+0x137/0x1f0 init/main.c:1389
       do_initcalls+0x4b/0x90 init/main.c:1405
       kernel_init_freeable+0x3ce/0x560 init/main.c:1629
       kernel_init+0x19/0x1b0 init/main.c:1520
       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:3203 [inline]
       add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3510 [inline]
       kvfree_call_rcu+0x186/0x7c0 kernel/rcu/tree.c:3601
       trie_delete_elem+0x58c/0x710 kernel/bpf/lpm_trie.c:-1
       bpf_prog_41385012b43a9f2e+0x40/0x4c
       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+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
       dsp_cmx_send+0x1ab4/0x1b30 drivers/isdn/mISDN/dsp_cmx.c:1850
       call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
       expire_timers kernel/time/timer.c:1496 [inline]
       __run_timers+0x525/0x7c0 kernel/time/timer.c:1767
       run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
       handle_softirqs+0x328/0x820 kernel/softirq.c:576
       __do_softirq kernel/softirq.c:610 [inline]
       invoke_softirq kernel/softirq.c:450 [inline]
       __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
       irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
       instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
       sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
       asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
       __text_poke+0x646/0x7b0 arch/x86/kernel/alternative.c:1389
       text_poke arch/x86/kernel/alternative.c:1413 [inline]
       text_poke_bp_batch+0x417/0x7c0 arch/x86/kernel/alternative.c:1664
       text_poke_flush arch/x86/kernel/alternative.c:1833 [inline]
       text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1840
       arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
       static_key_enable_cpuslocked+0x11f/0x240 kernel/jump_label.c:177
       static_key_enable+0x16/0x20 kernel/jump_label.c:190
       tracepoint_add_func+0x83b/0x9a0 kernel/tracepoint.c:361
       tracepoint_probe_register_prio_may_exist+0x5c/0x90 kernel/tracepoint.c:482
       bpf_raw_tracepoint_open+0x69d/0x780 kernel/bpf/syscall.c:3119
       __sys_bpf+0x48b/0x670 kernel/bpf/syscall.c:4699
       __do_sys_bpf kernel/bpf/syscall.c:4761 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:4759 [inline]
       __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4759
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

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 ***

10 locks held by syz.0.22/4324:
 #0: ffffffff8c15c488 (tracepoints_mutex){+.+.}-{3:3}, at: tracepoint_probe_register_prio_may_exist+0x40/0x90 kernel/tracepoint.c:478
 #1: ffffffff8bfbae90 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_enable+0xe/0x20 kernel/jump_label.c:189
 #2: ffffffff8c1a8568 (jump_label_mutex){+.+.}-{3:3}, at: jump_label_lock kernel/jump_label.c:27 [inline]
 #2: ffffffff8c1a8568 (jump_label_mutex){+.+.}-{3:3}, at: static_key_enable_cpuslocked+0xc2/0x240 kernel/jump_label.c:174
 #3: ffffffff8bfd1f48 (text_mutex){+.+.}-{3:3}, at: arch_jump_label_transform_apply+0xe/0x20 arch/x86/kernel/jump_label.c:145
 #4: ffff888016866078 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
 #4: ffff888016866078 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: __get_locked_pte+0x162/0x1b0 mm/memory.c:1760
 #5: ffffc90000007be0 ((&dsp_spl_tl)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline]
 #5: ffffc90000007be0 ((&dsp_spl_tl)){+.-.}-{0:0}, at: call_timer_fn+0xbb/0x530 kernel/time/timer.c:1441
 #6: ffffffff8cfdd4d8 (dsp_lock){..-.}-{2:2}, at: dsp_cmx_send+0x22/0x1b30 drivers/isdn/mISDN/dsp_cmx.c:1643
 #7: ffff8880b90280d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:946
 #8: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
 #9: ffff88807d446238 (&trie->lock){..-.}-{2:2}, at: trie_delete_elem+0x90/0x710 kernel/bpf/lpm_trie.c:467

stack backtrace:
CPU: 0 PID: 4324 Comm: syz.0.22 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <IRQ>
 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:3203 [inline]
 add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3510 [inline]
 kvfree_call_rcu+0x186/0x7c0 kernel/rcu/tree.c:3601
 trie_delete_elem+0x58c/0x710 kernel/bpf/lpm_trie.c:-1
 bpf_prog_41385012b43a9f2e+0x40/0x4c
 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+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
 dsp_cmx_send+0x1ab4/0x1b30 drivers/isdn/mISDN/dsp_cmx.c:1850
 call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
 expire_timers kernel/time/timer.c:1496 [inline]
 __run_timers+0x525/0x7c0 kernel/time/timer.c:1767
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
 handle_softirqs+0x328/0x820 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:spin_unlock include/linux/spinlock.h:404 [inline]
RIP: 0010:__text_poke+0x646/0x7b0 arch/x86/kernel/alternative.c:1389
Code: 00 00 00 00 00 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 75 6f 41 f7 c6 00 02 00 00 74 01 fb 48 8b bc 24 c0 00 00 00 <e8> 05 6b 80 08 48 c7 44 24 60 0e 36 e0 45 48 b8 00 00 00 00 00 fc
RSP: 0018:ffffc9000325f8c0 EFLAGS: 00000206
RAX: bbf37241554d7200 RBX: 1ffff9200064bf24 RCX: bbf37241554d7200
RDX: dffffc0000000000 RSI: ffffffff8a0b1be0 RDI: ffff888016866060
RBP: ffffc9000325f9f0 R08: dffffc0000000000 R09: fffffbfff1ff5419
R10: fffffbfff1ff5419 R11: 1ffffffff1ff5418 R12: ffff8880770dbb80
R13: ffff888016867558 R14: 0000000000000282 R15: ffffffff81675a39
 text_poke arch/x86/kernel/alternative.c:1413 [inline]
 text_poke_bp_batch+0x417/0x7c0 arch/x86/kernel/alternative.c:1664
 text_poke_flush arch/x86/kernel/alternative.c:1833 [inline]
 text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1840
 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x11f/0x240 kernel/jump_label.c:177
 static_key_enable+0x16/0x20 kernel/jump_label.c:190
 tracepoint_add_func+0x83b/0x9a0 kernel/tracepoint.c:361
 tracepoint_probe_register_prio_may_exist+0x5c/0x90 kernel/tracepoint.c:482
 bpf_raw_tracepoint_open+0x69d/0x780 kernel/bpf/syscall.c:3119
 __sys_bpf+0x48b/0x670 kernel/bpf/syscall.c:4699
 __do_sys_bpf kernel/bpf/syscall.c:4761 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4759 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4759
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f618f46a749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd68be1168 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f618f6c0fa0 RCX: 00007f618f46a749
RDX: 0000000000000010 RSI: 0000200000000040 RDI: 0000000000000011
RBP: 00007f618f4eef91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f618f6c0fa0 R14: 00007f618f6c0fa0 R15: 0000000000000003
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	00 00                	add    %al,(%rax)
   4:	00 00                	add    %al,(%rax)
   6:	9c                   	pushf
   7:	8f 84 24 80 00 00 00 	pop    0x80(%rsp)
   e:	f6 84 24 81 00 00 00 	testb  $0x2,0x81(%rsp)
  15:	02
  16:	75 6f                	jne    0x87
  18:	41 f7 c6 00 02 00 00 	test   $0x200,%r14d
  1f:	74 01                	je     0x22
  21:	fb                   	sti
  22:	48 8b bc 24 c0 00 00 	mov    0xc0(%rsp),%rdi
  29:	00
* 2a:	e8 05 6b 80 08       	call   0x8806b34 <-- trapping instruction
  2f:	48 c7 44 24 60 0e 36 	movq   $0x45e0360e,0x60(%rsp)
  36:	e0 45
  38:	48                   	rex.W
  39:	b8 00 00 00 00       	mov    $0x0,%eax
  3e:	00 fc                	add    %bh,%ah