======================================================
WARNING: possible circular locking dependency detected
5.15.186-syzkaller #0 Not tainted
------------------------------------------------------
syz.3.17/4330 is trying to acquire lock:
ffff8880b9027e78 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3199 [inline]
ffff8880b9027e78 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3506 [inline]
ffff8880b9027e78 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x186/0x7c0 kernel/rcu/tree.c:3597

but task is already holding lock:
ffff8880229211b8 (&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
       0xffffffffa0016061
       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
       mrp_join_timer_arm net/802/mrp.c:596 [inline]
       mrp_join_timer+0x142/0x180 net/802/mrp.c:611
       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
       check_kcov_mode kernel/kcov.c:174 [inline]
       __sanitizer_cov_trace_pc+0x32/0x60 kernel/kcov.c:206
       find_va_links mm/vmalloc.c:894 [inline]
       merge_or_add_vmap_area mm/vmalloc.c:1087 [inline]
       merge_or_add_vmap_area_augment mm/vmalloc.c:1161 [inline]
       __purge_vmap_area_lazy+0x410/0x18f0 mm/vmalloc.c:1697
       _vm_unmap_aliases+0x410/0x4a0 mm/vmalloc.c:2107
       change_page_attr_set_clr+0x311/0xc10 arch/x86/mm/pat/set_memory.c:1740
       change_page_attr_clear arch/x86/mm/pat/set_memory.c:1797 [inline]
       set_memory_ro+0x89/0xd0 arch/x86/mm/pat/set_memory.c:1943
       bpf_jit_binary_lock_ro include/linux/filter.h:899 [inline]
       bpf_int_jit_compile+0xc4a8/0xcc80 arch/x86/net/bpf_jit_comp.c:2478
       bpf_prog_select_runtime+0x74f/0xaa0 kernel/bpf/core.c:1934
       bpf_prog_load+0x106e/0x1550 kernel/bpf/syscall.c:2352
       __sys_bpf+0x4c2/0x670 kernel/bpf/syscall.c:4651
       __do_sys_bpf kernel/bpf/syscall.c:4755 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:4753 [inline]
       __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4753
       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: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:3795
       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_8c8ab8634bca3061+0x3a/0xb98
       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
       __bpf_trace_kmem_cache_free+0x99/0xc0 include/trace/events/kmem.h:138
       trace_kmem_cache_free include/trace/events/kmem.h:138 [inline]
       kmem_cache_free+0x1e7/0x210 mm/slub.c:3516
       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+0x13b/0x200 kernel/softirq.c:477
       __local_bh_enable_ip+0x174/0x1b0 kernel/softirq.c:401
       sk_psock_init+0x65b/0x730 net/core/skmsg.c:755
       sock_map_link+0x64e/0xd10 net/core/sock_map.c:278
       sock_map_update_common+0xe1/0x5f0 net/core/sock_map.c:488
       sock_map_update_elem_sys+0x3bf/0x5d0 net/core/sock_map.c:588
       map_update_elem+0x626/0x770 kernel/bpf/syscall.c:1188
       __sys_bpf+0x3fb/0x670 kernel/bpf/syscall.c:4639
       __do_sys_bpf kernel/bpf/syscall.c:4755 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:4753 [inline]
       __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4753
       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 ***

5 locks held by syz.3.17/4330:
 #0: ffff888026fdb120 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1694 [inline]
 #0: ffff888026fdb120 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_sk_acquire net/core/sock_map.c:119 [inline]
 #0: ffff888026fdb120 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_update_elem_sys+0x1a3/0x5d0 net/core/sock_map.c:584
 #1: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
 #2: ffffffff8c11c0c0 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x0/0x20
 #3: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
 #4: ffff8880229211b8 (&trie->lock){..-.}-{2:2}, at: trie_delete_elem+0x90/0x710 kernel/bpf/lpm_trie.c:467

stack backtrace:
CPU: 0 PID: 4330 Comm: syz.3.17 Not tainted 5.15.186-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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: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_8c8ab8634bca3061+0x3a/0xb98
 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
 __bpf_trace_kmem_cache_free+0x99/0xc0 include/trace/events/kmem.h:138
 trace_kmem_cache_free include/trace/events/kmem.h:138 [inline]
 kmem_cache_free+0x1e7/0x210 mm/slub.c:3516
 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+0x13b/0x200 kernel/softirq.c:477
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x174/0x1b0 kernel/softirq.c:401
 sk_psock_init+0x65b/0x730 net/core/skmsg.c:755
 sock_map_link+0x64e/0xd10 net/core/sock_map.c:278
 sock_map_update_common+0xe1/0x5f0 net/core/sock_map.c:488
 sock_map_update_elem_sys+0x3bf/0x5d0 net/core/sock_map.c:588
 map_update_elem+0x626/0x770 kernel/bpf/syscall.c:1188
 __sys_bpf+0x3fb/0x670 kernel/bpf/syscall.c:4639
 __do_sys_bpf kernel/bpf/syscall.c:4755 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4753 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4753
 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: 0033:0x7f5fad50f929
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:00007f5fab377038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f5fad736fa0 RCX: 00007f5fad50f929
RDX: 0000000000000020 RSI: 0000200000000740 RDI: 0000000000000002
RBP: 00007f5fad591b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f5fad736fa0 R15: 00007fffda74a018
 </TASK>