======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.3.3314/17104 is trying to acquire lock:
ffff88802a045238 (&trie->lock){..-.}-{2:2}, at: trie_delete_elem+0x90/0x710 kernel/bpf/lpm_trie.c:467

but task is already holding lock:
ffff8880b91280d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:946

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&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

-> #1 (krc.lock){..-.}-{2:2}:
       __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_update_elem+0x86e/0xc50 kernel/bpf/lpm_trie.c:396
       bpf_map_update_value+0x57d/0x650 kernel/bpf/syscall.c:223
       generic_map_update_batch+0x525/0x7c0 kernel/bpf/syscall.c:1430
       bpf_map_do_batch+0x466/0x600 kernel/bpf/syscall.c:-1
       __sys_bpf+0x601/0x670 kernel/bpf/syscall.c:-1
       __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

-> #0 (&trie->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_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_e6a446e6ec7b690a+0x40/0x8e8
       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
       __traceiter_timer_start+0x73/0xc0 include/trace/events/timer.h:52
       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
       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
       debug_lockdep_rcu_enabled+0x0/0x30
       rcu_read_unlock include/linux/rcupdate.h:769 [inline]
       count_memcg_event_mm+0x292/0x360 include/linux/memcontrol.h:1082
       handle_mm_fault+0x12d/0x43b0 mm/memory.c:4863
       do_user_addr_fault+0x489/0xc80 arch/x86/mm/fault.c:1357
       handle_page_fault arch/x86/mm/fault.c:1445 [inline]
       exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1501
       asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606

other info that might help us debug this:

Chain exists of:
  &trie->lock --> krc.lock --> &base->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&base->lock);
                               lock(krc.lock);
                               lock(&base->lock);
  lock(&trie->lock);

 *** DEADLOCK ***

5 locks held by syz.3.3314/17104:
 #0: ffff88807daa3228 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
 #0: ffff88807daa3228 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2b9/0xc80 arch/x86/mm/fault.c:1298
 #1: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
 #2: ffffc90000dd0be0 ((&app->join_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline]
 #2: ffffc90000dd0be0 ((&app->join_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbb/0x530 kernel/time/timer.c:1441
 #3: ffff8880b91280d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:946
 #4: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312

stack backtrace:
CPU: 1 PID: 17104 Comm: syz.3.3314 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_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_e6a446e6ec7b690a+0x40/0x8e8
 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
 __traceiter_timer_start+0x73/0xc0 include/trace/events/timer.h:52
 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
 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:debug_lockdep_rcu_enabled+0x0/0x30 kernel/rcu/update.c:279
Code: 7c c7 03 00 75 e8 48 c7 c7 80 1a 0b 8a 48 c7 c6 00 3f 0b 8a e8 01 3b f5 ff 0f 0b eb d1 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 <31> c0 83 3d bb 49 c7 03 00 74 1d 83 3d 32 7c c7 03 00 74 14 65 48
RSP: 0000:ffffc9000324fbf8 EFLAGS: 00000293
RAX: ffffffff81ac499c RBX: 0000000000000000 RCX: ffff888028520000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000324fcb0 R08: dffffc0000000000 R09: fffffbfff1ff541f
R10: fffffbfff1ff541f R11: 1ffffffff1ff541e R12: dffffc0000000000
R13: 1ffff92000649f80 R14: ffff88802a2a8000 R15: 0000000000000200
 rcu_read_unlock include/linux/rcupdate.h:769 [inline]
 count_memcg_event_mm+0x292/0x360 include/linux/memcontrol.h:1082
 handle_mm_fault+0x12d/0x43b0 mm/memory.c:4863
 do_user_addr_fault+0x489/0xc80 arch/x86/mm/fault.c:1357
 handle_page_fault arch/x86/mm/fault.c:1445 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1501
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
RIP: 0033:0x7fcffc41a75c
Code: 23 83 c0 01 44 39 d0 75 dc 48 89 f0 25 ff 1f 00 00 49 89 34 c1 41 88 3c 00 31 c0 c3 66 90 41 38 3c 10 74 0b 41 88 3c 10 31 c0 <49> 89 34 d1 c3 b8 01 00 00 00 c3 66 0f 1f 84 00 00 00 00 00 48 83
RSP: 002b:00007ffc86e2dfc8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 00007fcffd2e2720 RCX: 0000000000000000
RDX: 0000000000001d64 RSI: ffffffff83fa3d64 RDI: 0000000000000000
RBP: ffffffff83fa3d64 R08: 00007fcffc79d000 R09: 00007fcffc79f000
R10: 0000000083fa3d68 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff83fa36cc R15: 0000000000000021
 </TASK>
------------[ cut here ]------------
WARNING: CPU: 1 PID: 17102 at mm/maccess.c:226 copy_from_user_nofault+0x160/0x1c0 mm/maccess.c:226
Modules linked in:
CPU: 1 PID: 17102 Comm: syz.2.3316 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:copy_from_user_nofault+0x160/0x1c0 mm/maccess.c:226
Code: 24 45 31 f6 31 ff 89 de e8 0d f6 d8 ff 85 db 48 c7 c0 f2 ff ff ff 49 0f 44 c6 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 90 f2 d8 ff <0f> 0b e9 1c ff ff ff 44 89 e1 80 e1 07 80 c1 03 38 c1 0f 8c ea fe
RSP: 0000:ffffc90002e3f938 EFLAGS: 00010246
RAX: ffffffff819ed980 RBX: 0000000000000008 RCX: ffff888022708000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed10044e1001
R10: ffffed10044e1001 R11: 1ffff110044e1000 R12: ffff888022709788
R13: 00007ffffffff000 R14: ffffc90002e3f9a8 R15: 0000000000000000
FS:  0000555564b05500(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c32643d CR3: 0000000064b22000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 bpf_probe_read_user_common kernel/trace/bpf_trace.c:157 [inline]
 ____bpf_probe_read_compat kernel/trace/bpf_trace.c:281 [inline]
 bpf_probe_read_compat+0xdd/0x170 kernel/trace/bpf_trace.c:277
 bpf_prog_ee60aafa828f4cb7+0x35/0xee4
 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_run2+0x15b/0x2d0 kernel/trace/bpf_trace.c:1915
 __bpf_trace_kfree+0x6e/0x90 include/trace/events/kmem.h:118
 trace_kfree include/trace/events/kmem.h:118 [inline]
 kfree+0x25f/0x2a0 mm/slub.c:4554
 shmem_free_in_core_inode+0x6f/0xb0 mm/shmem.c:3798
 rcu_do_batch kernel/rcu/tree.c:2523 [inline]
 rcu_core+0x962/0x15d0 kernel/rcu/tree.c:2763
 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+0x52/0xc0 arch/x86/kernel/apic/apic.c:1108
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0033:0x7f48cc4c2fc8
Code: 48 89 d5 74 28 25 ff 0f 00 00 83 f0 3d 8d 04 c0 89 c5 c1 ed 04 31 c5 69 ed 2d eb d4 27 89 e8 c1 e8 0f 31 c5 81 e5 ff 0f 00 00 <48> 31 d5 80 3d 76 30 37 00 00 0f 84 a8 00 00 00 4c 89 f6 48 8b 0d
RSP: 002b:00007fff9dd55fc0 EFLAGS: 00000206
RAX: 0000000000009cc4 RBX: 00007f48cd369720 RCX: 000000000005add7
RDX: ffffffff816c863b RSI: ffffffff816c8c0e RDI: 0000000000000001
RBP: 0000000000000a35 R08: 00007f48cc83a038 R09: 00007f48cc826000
R10: 00007f48cc053008 R11: 0000000000000001 R12: 0000000000000001
R13: 0000000000000000 R14: ffffffff816c863b R15: 000000000005add7
 </TASK>