======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.208/4617 is trying to acquire lock:
ffff8880b8e28218 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:2995 [inline]
ffff8880b8e28218 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3315 [inline]
ffff8880b8e28218 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x18b/0x890 kernel/rcu/tree.c:3406

but task is already holding lock:
ffff8880b8e28458 (&base->lock){-.-.}-{2:2}, at: __run_timers+0x127/0x810 kernel/time/timer.c:2005

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+0xb0/0x100 kernel/locking/spinlock.c:162
       lock_timer_base+0x123/0x270 kernel/time/timer.c:999
       __mod_timer+0xf9/0xd20 kernel/time/timer.c:1080
       queue_delayed_work_on+0x12d/0x1f0 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+0x4fb/0x890 kernel/rcu/tree.c:3432
       rtnl_register_internal+0x485/0x590 net/core/rtnetlink.c:260
       rtnl_register+0x2e/0x70 net/core/rtnetlink.c:310
       ip_rt_init+0x324/0x3b6 net/ipv4/route.c:3753
       ip_init+0xa/0x14 net/ipv4/ip_output.c:1779
       inet_init+0x2bd/0x3cf net/ipv4/af_inet.c:2033
       do_one_initcall+0x257/0x800 init/main.c:1309
       do_initcall_level+0x13d/0x1ed init/main.c:1382
       do_initcalls+0x4b/0x8a init/main.c:1398
       kernel_init_freeable+0x401/0x5ab init/main.c:1637
       kernel_init+0x19/0x1b0 init/main.c:1525
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

-> #0 (krc.lock){..-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3095 [inline]
       check_prevs_add kernel/locking/lockdep.c:3214 [inline]
       validate_chain kernel/locking/lockdep.c:3830 [inline]
       __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063
       lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676
       __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+0x18b/0x890 kernel/rcu/tree.c:3406
       trie_delete_elem+0x4e9/0x620 kernel/bpf/lpm_trie.c:543
       bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e
       bpf_dispatcher_nop_func include/linux/bpf.h:1012 [inline]
       __bpf_prog_run include/linux/filter.h:607 [inline]
       bpf_prog_run include/linux/filter.h:614 [inline]
       bpf_prog_run_array include/linux/bpf.h:1668 [inline]
       trace_call_bpf+0x322/0x6b0 kernel/trace/bpf_trace.c:135
       perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10027
       perf_trace_timer_class+0x264/0x2e0 include/trace/events/timer.h:12
       trace_timer_cancel include/trace/events/timer.h:138 [inline]
       debug_deactivate kernel/time/timer.c:832 [inline]
       detach_timer+0x2c0/0x350 kernel/time/timer.c:878
       expire_timers kernel/time/timer.c:1735 [inline]
       __run_timers+0x4ed/0x810 kernel/time/timer.c:2023
       run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
       handle_softirqs+0x291/0x910 kernel/softirq.c:596
       __do_softirq kernel/softirq.c:630 [inline]
       invoke_softirq kernel/softirq.c:470 [inline]
       __irq_exit_rcu+0x13b/0x230 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_release+0x5ab/0x920 kernel/locking/lockdep.c:5700
       __raw_spin_unlock include/linux/spinlock_api_smp.h:141 [inline]
       _raw_spin_unlock+0x12/0x40 kernel/locking/spinlock.c:186
       spin_unlock include/linux/spinlock.h:391 [inline]
       dentry_unlink_inode+0x186/0x3b0 fs/dcache.c:398
       __dentry_kill+0x412/0x630 fs/dcache.c:611
       dentry_kill+0xb8/0x290 fs/dcache.c:-1
       dput+0xfa/0x1d0 fs/dcache.c:918
       __fput+0x597/0x8b0 fs/file_table.c:328
       task_work_run+0x1d0/0x260 kernel/task_work.c:203
       resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
       exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
       exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
       __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
       syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
       do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
       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 ***

3 locks held by syz.0.208/4617:
 #0: ffff888140cce410 (&sb->s_type->i_lock_key#15){+.+.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
 #0: ffff888140cce410 (&sb->s_type->i_lock_key#15){+.+.}-{2:2}, at: dentry_kill+0x4b/0x290 fs/dcache.c:721
 #1: ffff8880b8e28458 (&base->lock){-.-.}-{2:2}, at: __run_timers+0x127/0x810 kernel/time/timer.c:2005
 #2: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #2: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #2: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: trace_call_bpf+0xbf/0x6b0 kernel/trace/bpf_trace.c:134

stack backtrace:
CPU: 0 PID: 4617 Comm: syz.0.208 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3095 [inline]
 check_prevs_add kernel/locking/lockdep.c:3214 [inline]
 validate_chain kernel/locking/lockdep.c:3830 [inline]
 __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676
 __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+0x18b/0x890 kernel/rcu/tree.c:3406
 trie_delete_elem+0x4e9/0x620 kernel/bpf/lpm_trie.c:543
 bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e
 bpf_dispatcher_nop_func include/linux/bpf.h:1012 [inline]
 __bpf_prog_run include/linux/filter.h:607 [inline]
 bpf_prog_run include/linux/filter.h:614 [inline]
 bpf_prog_run_array include/linux/bpf.h:1668 [inline]
 trace_call_bpf+0x322/0x6b0 kernel/trace/bpf_trace.c:135
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10027
 perf_trace_timer_class+0x264/0x2e0 include/trace/events/timer.h:12
 trace_timer_cancel include/trace/events/timer.h:138 [inline]
 debug_deactivate kernel/time/timer.c:832 [inline]
 detach_timer+0x2c0/0x350 kernel/time/timer.c:878
 expire_timers kernel/time/timer.c:1735 [inline]
 __run_timers+0x4ed/0x810 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x291/0x910 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 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_release+0x5ab/0x920 kernel/locking/lockdep.c:5700
Code: 00 00 00 f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 2f 04 f8 75 70 f7 44 24 50 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 2f 00 00 00 00 43 c7 44 2f 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc900040e7b60 EFLAGS: 00000206
RAX: 0000000000000001 RBX: ffffffffffffffff RCX: b5291e8ea04f3b00
RDX: 00000000ffffffff RSI: ffffffff8a8c2920 RDI: ffffffff8adf5de0
RBP: ffffc900040e7c80 R08: dffffc0000000000 R09: 1ffffffff2161e4f
R10: dffffc0000000000 R11: fffffbfff2161e50 R12: ffff888079f3e4e0
R13: dffffc0000000000 R14: ffff888079f3e4d0 R15: 1ffff9200081cf78
 __raw_spin_unlock include/linux/spinlock_api_smp.h:141 [inline]
 _raw_spin_unlock+0x12/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 dentry_unlink_inode+0x186/0x3b0 fs/dcache.c:398
 __dentry_kill+0x412/0x630 fs/dcache.c:611
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xfa/0x1d0 fs/dcache.c:918
 __fput+0x597/0x8b0 fs/file_table.c:328
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ffa96d9de99
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffef26bfb88 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffef26bfc70 RCX: 00007ffa96d9de99
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000001be5b R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2db20000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffa97025fac R14: 00007ffa97025fa8 R15: 00007ffa97025fa0
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	00 f7                	add    %dh,%bh
   4:	84 24 80             	test   %ah,(%rax,%rax,4)
   7:	00 00                	add    %al,(%rax)
   9:	00 00                	add    %al,(%rax)
   b:	02 00                	add    (%rax),%al
   d:	00 43 c6             	add    %al,-0x3a(%rbx)
  10:	44 2f                	rex.R (bad)
  12:	04 f8                	add    $0xf8,%al
  14:	75 70                	jne    0x86
  16:	f7 44 24 50 00 02 00 	testl  $0x200,0x50(%rsp)
  1d:	00
  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 04 2f 00 00 00 	movq   $0x0,(%r15,%r13,1) <-- trapping instruction
  31:	00
  32:	43 c7 44 2f 08 00 00 	movl   $0x0,0x8(%r15,%r13,1)
  39:	00 00
  3b:	65                   	gs
  3c:	48                   	rex.W
  3d:	8b                   	.byte 0x8b
  3e:	04 25                	add    $0x25,%al