======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.5203/25374 is trying to acquire lock:
ffff8880b8e295a8 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:2959 [inline]
ffff8880b8e295a8 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3368 [inline]
ffff8880b8e295a8 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3453

but task is already holding lock:
ffff8880b8e297d8 (&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+0xa8/0xf0 kernel/locking/spinlock.c:162
       lock_timer_base+0x123/0x270 kernel/time/timer.c:999
       __mod_timer+0xf9/0xdb0 kernel/time/timer.c:1080
       queue_delayed_work_on+0x12a/0x1e0 kernel/workqueue.c:1987
       kvfree_call_rcu+0x541/0x780 kernel/rcu/tree.c:3481
       rtnl_register_internal+0x486/0x590 net/core/rtnetlink.c:264
       rtnl_register+0x32/0x70 net/core/rtnetlink.c:314
       ip_rt_init+0x2ec/0x390 net/ipv4/route.c:3792
       ip_init+0xe/0x20 net/ipv4/ip_output.c:1663
       inet_init+0x2c1/0x3e0 net/ipv4/af_inet.c:2024
       do_one_initcall+0x1fd/0x750 init/main.c:1238
       do_initcall_level+0x137/0x1f0 init/main.c:1300
       do_initcalls+0x69/0xd0 init/main.c:1316
       kernel_init_freeable+0x3d2/0x570 init/main.c:1553
       kernel_init+0x1d/0x1c0 init/main.c:1443
       ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

-> #0 (krc.lock){..-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
       lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       krc_this_cpu_lock kernel/rcu/tree.c:2959 [inline]
       add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3368 [inline]
       kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3453
       trie_delete_elem+0x535/0x6a0 kernel/bpf/lpm_trie.c:545
       bpf_prog_5186c38a4019a4cb+0x4a/0x4e
       bpf_dispatcher_nop_func include/linux/bpf.h:1213 [inline]
       __bpf_prog_run include/linux/filter.h:612 [inline]
       bpf_prog_run include/linux/filter.h:619 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline]
       bpf_trace_run3+0x1e7/0x400 kernel/trace/bpf_trace.c:2362
       __bpf_trace_timer_start+0x14a/0x1b0 include/trace/events/timer.h:53
       trace_timer_start include/trace/events/timer.h:53 [inline]
       enqueue_timer+0x398/0x530 kernel/time/timer.c:609
       internal_add_timer kernel/time/timer.c:634 [inline]
       __mod_timer+0x977/0xdb0 kernel/time/timer.c:1131
       dsp_cmx_send+0x1ab8/0x1b40 drivers/isdn/mISDN/dsp_cmx.c:1839
       call_timer_fn+0x16e/0x530 kernel/time/timer.c:1700
       expire_timers kernel/time/timer.c:1751 [inline]
       __run_timers+0x52d/0x7d0 kernel/time/timer.c:2022
       run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2035
       handle_softirqs+0x280/0x820 kernel/softirq.c:578
       __do_softirq kernel/softirq.c:612 [inline]
       invoke_softirq kernel/softirq.c:452 [inline]
       __irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661
       irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
       instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
       sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
       asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
       try_charge_memcg+0x462/0x1810 mm/memcontrol.c:2655
       obj_cgroup_charge_pages mm/memcontrol.c:3109 [inline]
       obj_cgroup_charge+0x358/0x620 mm/memcontrol.c:3400
       memcg_slab_pre_alloc_hook mm/slab.h:508 [inline]
       slab_pre_alloc_hook+0x2eb/0x310 mm/slab.h:719
       slab_alloc_node mm/slub.c:3467 [inline]
       slab_alloc mm/slub.c:3493 [inline]
       __kmem_cache_alloc_lru mm/slub.c:3500 [inline]
       kmem_cache_alloc+0x5a/0x2e0 mm/slub.c:3509
       sk_prot_alloc+0x57/0x210 net/core/sock.c:2088
       sk_alloc+0x3a/0x360 net/core/sock.c:2147
       tipc_sk_create+0x165/0x28b0 net/tipc/socket.c:489
       __sock_create+0x4a6/0x940 net/socket.c:1571
       sock_create net/socket.c:1627 [inline]
       __sys_socketpair+0x236/0x550 net/socket.c:1782
       __do_sys_socketpair net/socket.c:1831 [inline]
       __se_sys_socketpair net/socket.c:1828 [inline]
       __x64_sys_socketpair+0x9b/0xb0 net/socket.c:1828
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 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 syz.4.5203/25374:
 #0: ffffc90000007c00 ((&dsp_spl_tl)){+.-.}-{0:0}, at: call_timer_fn+0xbf/0x530 kernel/time/timer.c:1697
 #1: ffffffff8dd232f8 (dsp_lock){..-.}-{2:2}, at: dsp_cmx_send+0x26/0x1b40 drivers/isdn/mISDN/dsp_cmx.c:1632
 #2: ffff8880b8e297d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:999
 #3: ffffffff8cd2fbe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #3: ffffffff8cd2fbe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #3: ffffffff8cd2fbe0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2321 [inline]
 #3: ffffffff8cd2fbe0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run3+0xf4/0x400 kernel/trace/bpf_trace.c:2362

stack backtrace:
CPU: 0 PID: 25374 Comm: syz.4.5203 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 krc_this_cpu_lock kernel/rcu/tree.c:2959 [inline]
 add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3368 [inline]
 kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3453
 trie_delete_elem+0x535/0x6a0 kernel/bpf/lpm_trie.c:545
 bpf_prog_5186c38a4019a4cb+0x4a/0x4e
 bpf_dispatcher_nop_func include/linux/bpf.h:1213 [inline]
 __bpf_prog_run include/linux/filter.h:612 [inline]
 bpf_prog_run include/linux/filter.h:619 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline]
 bpf_trace_run3+0x1e7/0x400 kernel/trace/bpf_trace.c:2362
 __bpf_trace_timer_start+0x14a/0x1b0 include/trace/events/timer.h:53
 trace_timer_start include/trace/events/timer.h:53 [inline]
 enqueue_timer+0x398/0x530 kernel/time/timer.c:609
 internal_add_timer kernel/time/timer.c:634 [inline]
 __mod_timer+0x977/0xdb0 kernel/time/timer.c:1131
 dsp_cmx_send+0x1ab8/0x1b40 drivers/isdn/mISDN/dsp_cmx.c:1839
 call_timer_fn+0x16e/0x530 kernel/time/timer.c:1700
 expire_timers kernel/time/timer.c:1751 [inline]
 __run_timers+0x52d/0x7d0 kernel/time/timer.c:2022
 run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2035
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:try_charge_memcg+0x462/0x1810 mm/memcontrol.c:2655
Code: b6 04 0f 49 89 cf 84 c0 0f 85 4b 0c 00 00 45 89 26 41 b4 01 e9 df fe ff ff e8 2a 55 89 08 f7 c3 00 02 00 00 74 c4 fb 45 84 e4 <0f> 85 78 10 00 00 e9 26 0d 00 00 44 89 f3 48 8b bc 24 b0 00 00 00
RSP: 0018:ffffc900046177a0 EFLAGS: 00000202
RAX: 454a66effc4a3500 RBX: 0000000000000283 RCX: 454a66effc4a3500
RDX: dffffc0000000000 RSI: ffffffff8aaaba20 RDI: ffffffff8afc7040
RBP: ffffc900046179d0 R08: ffffffff8e4a8f2f R09: 1ffffffff1c951e5
R10: dffffc0000000000 R11: fffffbfff1c951e6 R12: 0000000000000001
R13: ffff88807d6f8000 R14: 0000000000000040 R15: dffffc0000000000
 obj_cgroup_charge_pages mm/memcontrol.c:3109 [inline]
 obj_cgroup_charge+0x358/0x620 mm/memcontrol.c:3400
 memcg_slab_pre_alloc_hook mm/slab.h:508 [inline]
 slab_pre_alloc_hook+0x2eb/0x310 mm/slab.h:719
 slab_alloc_node mm/slub.c:3467 [inline]
 slab_alloc mm/slub.c:3493 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3500 [inline]
 kmem_cache_alloc+0x5a/0x2e0 mm/slub.c:3509
 sk_prot_alloc+0x57/0x210 net/core/sock.c:2088
 sk_alloc+0x3a/0x360 net/core/sock.c:2147
 tipc_sk_create+0x165/0x28b0 net/tipc/socket.c:489
 __sock_create+0x4a6/0x940 net/socket.c:1571
 sock_create net/socket.c:1627 [inline]
 __sys_socketpair+0x236/0x550 net/socket.c:1782
 __do_sys_socketpair net/socket.c:1831 [inline]
 __se_sys_socketpair net/socket.c:1828 [inline]
 __x64_sys_socketpair+0x9b/0xb0 net/socket.c:1828
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff1e618ebe9
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:00007ff1e6f8d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000035
RAX: ffffffffffffffda RBX: 00007ff1e63c5fa0 RCX: 00007ff1e618ebe9
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 000000000000001e
RBP: 00007ff1e6211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000940 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff1e63c6038 R14: 00007ff1e63c5fa0 R15: 00007fff9bd16f98
 </TASK>
----------------
Code disassembly (best guess):
   0:	b6 04                	mov    $0x4,%dh
   2:	0f 49 89 cf 84 c0 0f 	cmovns 0xfc084cf(%rcx),%ecx
   9:	85 4b 0c             	test   %ecx,0xc(%rbx)
   c:	00 00                	add    %al,(%rax)
   e:	45 89 26             	mov    %r12d,(%r14)
  11:	41 b4 01             	mov    $0x1,%r12b
  14:	e9 df fe ff ff       	jmp    0xfffffef8
  19:	e8 2a 55 89 08       	call   0x8895548
  1e:	f7 c3 00 02 00 00    	test   $0x200,%ebx
  24:	74 c4                	je     0xffffffea
  26:	fb                   	sti
  27:	45 84 e4             	test   %r12b,%r12b
* 2a:	0f 85 78 10 00 00    	jne    0x10a8 <-- trapping instruction
  30:	e9 26 0d 00 00       	jmp    0xd5b
  35:	44 89 f3             	mov    %r14d,%ebx
  38:	48 8b bc 24 b0 00 00 	mov    0xb0(%rsp),%rdi
  3f:	00