======================================================
WARNING: possible circular locking dependency detected
6.1.141-syzkaller #0 Not tainted
------------------------------------------------------
udevd/3623 is trying to acquire lock:
ffff8880b8f281d8 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:2991 [inline]
ffff8880b8f281d8 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3311 [inline]
ffff8880b8f281d8 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x184/0x870 kernel/rcu/tree.c:3402

but task is already holding lock:
ffff8880b8f28418 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:999

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #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:999
       __mod_timer+0x117/0xd20 kernel/time/timer.c:1072
       queue_delayed_work_on+0x126/0x1e0 kernel/workqueue.c:1704
       queue_delayed_work include/linux/workqueue.h:527 [inline]
       schedule_delayed_monitor_work kernel/rcu/tree.c:3172 [inline]
       kvfree_call_rcu+0x4cb/0x870 kernel/rcu/tree.c:3428
       rtnl_register_internal+0x489/0x590 net/core/rtnetlink.c:260
       rtnl_register+0x2e/0x70 net/core/rtnetlink.c:310
       ip_rt_init+0x323/0x3b5 net/ipv4/route.c:3789
       ip_init+0xa/0x14 net/ipv4/ip_output.c:1771
       inet_init+0x2bd/0x3cf net/ipv4/af_inet.c:2033
       do_one_initcall+0x214/0x7a0 init/main.c:1298
       do_initcall_level+0x137/0x1e4 init/main.c:1371
       do_initcalls+0x4b/0x8a init/main.c:1387
       kernel_init_freeable+0x3fa/0x5ac init/main.c:1626
       kernel_init+0x19/0x1b0 init/main.c:1514
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

-> #0 (krc.lock){..-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
       lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
       krc_this_cpu_lock kernel/rcu/tree.c:2991 [inline]
       add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3311 [inline]
       kvfree_call_rcu+0x184/0x870 kernel/rcu/tree.c:3402
       trie_delete_elem+0x52d/0x690 kernel/bpf/lpm_trie.c:545
       bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e
       bpf_dispatcher_nop_func include/linux/bpf.h:1001 [inline]
       __bpf_prog_run include/linux/filter.h:603 [inline]
       bpf_prog_run include/linux/filter.h:610 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2285 [inline]
       bpf_trace_run3+0x1e3/0x400 kernel/trace/bpf_trace.c:2325
       __traceiter_timer_start+0x73/0xc0 include/trace/events/timer.h:53
       trace_timer_start include/trace/events/timer.h:53 [inline]
       enqueue_timer+0x411/0x5c0 kernel/time/timer.c:609
       internal_add_timer kernel/time/timer.c:634 [inline]
       __mod_timer+0x8e1/0xd20 kernel/time/timer.c:1115
       mrp_join_timer_arm net/802/mrp.c:596 [inline]
       mrp_join_timer+0x13b/0x170 net/802/mrp.c:611
       call_timer_fn+0x1a0/0x670 kernel/time/timer.c:1504
       expire_timers kernel/time/timer.c:1549 [inline]
       __run_timers+0x525/0x7c0 kernel/time/timer.c:1820
       run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1833
       handle_softirqs+0x2a1/0x920 kernel/softirq.c:596
       __do_softirq kernel/softirq.c:630 [inline]
       invoke_softirq kernel/softirq.c:470 [inline]
       __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679
       irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
       instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
       sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
       asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
       unwind_next_frame+0x1802/0x20b0 arch/x86/kernel/unwind_orc.c:622
       arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
       stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
       kasan_save_stack+0x3a/0x60 mm/kasan/common.c:45
       __kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486
       call_rcu+0x14b/0x970 kernel/rcu/tree.c:2845
       __dentry_kill+0x4ef/0x650 fs/dcache.c:625
       dentry_kill+0xb8/0x290 fs/dcache.c:-1
       dput+0xfa/0x1d0 fs/dcache.c:918
       handle_mounts fs/namei.c:1551 [inline]
       step_into+0xa12/0xf10 fs/namei.c:1836
       lookup_last fs/namei.c:2455 [inline]
       path_lookupat+0x169/0x440 fs/namei.c:2479
       filename_lookup+0x1f0/0x500 fs/namei.c:2508
       user_path_at_empty+0x3e/0x60 fs/namei.c:2905
       do_readlinkat+0xd4/0x480 fs/stat.c:468
       __do_sys_readlink fs/stat.c:501 [inline]
       __se_sys_readlink fs/stat.c:498 [inline]
       __x64_sys_readlink+0x7b/0x90 fs/stat.c:498
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

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 ***

4 locks held by udevd/3623:
 #0: ffffc900001e0bc0 ((&app->join_timer)){+.-.}-{0:0}, at: call_timer_fn+0xc1/0x670 kernel/time/timer.c:1501
 #1: ffff8880576a9cc8 (&app->lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #1: ffff8880576a9cc8 (&app->lock){+.-.}-{2:2}, at: mrp_join_timer+0xd4/0x170 net/802/mrp.c:609
 #2: ffff8880b8f28418 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:999
 #3: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #3: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #3: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline]
 #3: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run3+0xf0/0x400 kernel/trace/bpf_trace.c:2325

stack backtrace:
CPU: 1 PID: 3623 Comm: udevd Not tainted 6.1.141-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 krc_this_cpu_lock kernel/rcu/tree.c:2991 [inline]
 add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3311 [inline]
 kvfree_call_rcu+0x184/0x870 kernel/rcu/tree.c:3402
 trie_delete_elem+0x52d/0x690 kernel/bpf/lpm_trie.c:545
 bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e
 bpf_dispatcher_nop_func include/linux/bpf.h:1001 [inline]
 __bpf_prog_run include/linux/filter.h:603 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2285 [inline]
 bpf_trace_run3+0x1e3/0x400 kernel/trace/bpf_trace.c:2325
 __traceiter_timer_start+0x73/0xc0 include/trace/events/timer.h:53
 trace_timer_start include/trace/events/timer.h:53 [inline]
 enqueue_timer+0x411/0x5c0 kernel/time/timer.c:609
 internal_add_timer kernel/time/timer.c:634 [inline]
 __mod_timer+0x8e1/0xd20 kernel/time/timer.c:1115
 mrp_join_timer_arm net/802/mrp.c:596 [inline]
 mrp_join_timer+0x13b/0x170 net/802/mrp.c:611
 call_timer_fn+0x1a0/0x670 kernel/time/timer.c:1504
 expire_timers kernel/time/timer.c:1549 [inline]
 __run_timers+0x525/0x7c0 kernel/time/timer.c:1820
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1833
 handle_softirqs+0x2a1/0x920 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:unwind_next_frame+0x1802/0x20b0 arch/x86/kernel/unwind_orc.c:622
Code: 99 00 49 8b 06 4d 39 fc 0f 96 c1 4c 39 f8 0f 97 c2 20 ca 80 fa 01 0f 85 82 00 00 00 49 8d 4f 08 4c 39 e1 76 79 48 39 c1 77 74 <4c> 3b bc 24 98 00 00 00 77 6a 4c 8d 73 28 4c 89 f0 48 c1 e8 03 42
RSP: 0018:ffffc90003087410 EFLAGS: 00000287
RAX: ffffc90003088000 RBX: ffffc900030874e8 RCX: ffffc90003087f00
RDX: ffffc90003087501 RSI: dffffc0000000000 RDI: ffffc900030874f0
RBP: ffffffff8e89a1dc R08: ffffc90003087ee8 R09: ffffc90003087538
R10: fffff52000610ea9 R11: 1ffff92000610ea7 R12: ffffc90003080000
R13: dffffc0000000000 R14: ffffc900030874f8 R15: ffffc90003087ef8
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486
 call_rcu+0x14b/0x970 kernel/rcu/tree.c:2845
 __dentry_kill+0x4ef/0x650 fs/dcache.c:625
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xfa/0x1d0 fs/dcache.c:918
 handle_mounts fs/namei.c:1551 [inline]
 step_into+0xa12/0xf10 fs/namei.c:1836
 lookup_last fs/namei.c:2455 [inline]
 path_lookupat+0x169/0x440 fs/namei.c:2479
 filename_lookup+0x1f0/0x500 fs/namei.c:2508
 user_path_at_empty+0x3e/0x60 fs/namei.c:2905
 do_readlinkat+0xd4/0x480 fs/stat.c:468
 __do_sys_readlink fs/stat.c:501 [inline]
 __se_sys_readlink fs/stat.c:498 [inline]
 __x64_sys_readlink+0x7b/0x90 fs/stat.c:498
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f655ad153a7
Code: 00 00 90 48 83 ec 10 48 63 ff 45 31 c9 45 31 c0 6a 00 31 c9 e8 8a 20 f9 ff 48 83 c4 18 c3 0f 1f 44 00 00 b8 59 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 21 ba 0d 00 f7 d8 64 89 02 48
RSP: 002b:00007ffe3eb3d6b8 EFLAGS: 00000206 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00007ffe3eb3d8c0 RCX: 00007f655ad153a7
RDX: 0000000000000200 RSI: 00007ffe3eb3d6c0 RDI: 00007ffe3eb3d8c0
RBP: 00005649df505910 R08: 0000000000000064 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 00007ffe3eb3d6c0
R13: 00005649ab500100 R14: 0000000000000000 R15: 00007ffe3eb3def0
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	49 8b 06             	mov    (%r14),%rax
   3:	4d 39 fc             	cmp    %r15,%r12
   6:	0f 96 c1             	setbe  %cl
   9:	4c 39 f8             	cmp    %r15,%rax
   c:	0f 97 c2             	seta   %dl
   f:	20 ca                	and    %cl,%dl
  11:	80 fa 01             	cmp    $0x1,%dl
  14:	0f 85 82 00 00 00    	jne    0x9c
  1a:	49 8d 4f 08          	lea    0x8(%r15),%rcx
  1e:	4c 39 e1             	cmp    %r12,%rcx
  21:	76 79                	jbe    0x9c
  23:	48 39 c1             	cmp    %rax,%rcx
  26:	77 74                	ja     0x9c
* 28:	4c 3b bc 24 98 00 00 	cmp    0x98(%rsp),%r15 <-- trapping instruction
  2f:	00
  30:	77 6a                	ja     0x9c
  32:	4c 8d 73 28          	lea    0x28(%rbx),%r14
  36:	4c 89 f0             	mov    %r14,%rax
  39:	48 c1 e8 03          	shr    $0x3,%rax
  3d:	42                   	rex.X