syzbot

======================================================
WARNING: possible circular locking dependency detected
6.1.147-syzkaller #0 Not tainted
------------------------------------------------------
syz.0.32/4453 is trying to acquire lock:
ffff8880b8e281d8 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:2995 [inline]
ffff8880b8e281d8 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3315 [inline]
ffff8880b8e281d8 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x184/0x870 kernel/rcu/tree.c:3406

but task is already holding lock:
ffff8880b8e28418 (&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:3176 [inline]
       kvfree_call_rcu+0x4cb/0x870 kernel/rcu/tree.c:3432
       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:3793
       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:2995 [inline]
       add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3315 [inline]
       kvfree_call_rcu+0x184/0x870 kernel/rcu/tree.c:3406
       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
       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
       dsp_cmx_send+0x1ab4/0x1b30 drivers/isdn/mISDN/dsp_cmx.c:1850
       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
       lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666
       rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
       rcu_read_lock include/linux/rcupdate.h:791 [inline]
       __range_close fs/file.c:691 [inline]
       __close_range+0x1e6/0x730 fs/file.c:755
       __do_sys_close_range fs/open.c:1476 [inline]
       __se_sys_close_range fs/open.c:1473 [inline]
       __x64_sys_close_range+0x76/0x80 fs/open.c:1473
       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 ***

5 locks held by syz.0.32/4453:
 #0: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: __range_close fs/file.c:691 [inline]
 #0: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: __close_range+0x1c5/0x730 fs/file.c:755
 #1: ffffc90000007bc0 ((&dsp_spl_tl)){+.-.}-{0:0}, at: call_timer_fn+0xc1/0x670 kernel/time/timer.c:1501
 #2: ffffffff8dac8ab8 (dsp_lock){..-.}-{2:2}, at: dsp_cmx_send+0x22/0x1b30 drivers/isdn/mISDN/dsp_cmx.c:1643
 #3: ffff8880b8e28418 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:999
 #4: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #4: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #4: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline]
 #4: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run3+0xf0/0x400 kernel/trace/bpf_trace.c:2325

stack backtrace:
CPU: 0 PID: 4453 Comm: syz.0.32 Not tainted 6.1.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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:2995 [inline]
 add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3315 [inline]
 kvfree_call_rcu+0x184/0x870 kernel/rcu/tree.c:3406
 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
 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
 dsp_cmx_send+0x1ab4/0x1b30 drivers/isdn/mISDN/dsp_cmx.c:1850
 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:lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc90003f67d00 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 9d8abf30e8bb1500
RDX: 0000000000000000 RSI: ffffffff8a8c15e0 RDI: ffffffff8adef320
RBP: ffffc90003f67e08 R08: dffffc0000000000 R09: fffffbfff215ba49
R10: fffffbfff215ba49 R11: 1ffffffff215ba48 R12: 0000000000000000
R13: 1ffff920007ecfac R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 __range_close fs/file.c:691 [inline]
 __close_range+0x1e6/0x730 fs/file.c:755
 __do_sys_close_range fs/open.c:1476 [inline]
 __se_sys_close_range fs/open.c:1473 [inline]
 __x64_sys_close_range+0x76/0x80 fs/open.c:1473
 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: 0033:0x7f994fb8ebe9
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:00007ffddda32558 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: ffffffffffffffda RBX: 00000000000165b9 RCX: 00007f994fb8ebe9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000001 R09: 00000006dda3284f
R10: 0000001b2cf20000 R11: 0000000000000246 R12: 00007f994fdb5fac
R13: 00007f994fdb5fa0 R14: ffffffffffffffff R15: 0000000000000003
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 9c 8f 84 24 80 00 	add    %bl,0x802484(%rdi,%rcx,4)
   7:	00 00                	add    %al,(%rax)
   9:	f6 84 24 81 00 00 00 	testb  $0x2,0x81(%rsp)
  10:	02
  11:	0f 85 f5 00 00 00    	jne    0x10c
  17:	41 f7 c6 00 02 00 00 	test   $0x200,%r14d
  1e:	74 01                	je     0x21
  20:	fb                   	sti
  21:	48 c7 44 24 60 0e 36 	movq   $0x45e0360e,0x60(%rsp)
  28:	e0 45
* 2a:	4b c7 44 3d 00 00 00 	movq   $0x0,0x0(%r13,%r15,1) <-- trapping instruction
  31:	00 00
  33:	66 43 c7 44 3d 09 00 	movw   $0x0,0x9(%r13,%r15,1)
  3a:	00
  3b:	43                   	rex.XB
  3c:	c6                   	.byte 0xc6
  3d:	44                   	rex.R
  3e:	3d                   	.byte 0x3d
  3f:	0b                   	.byte 0xb