====================================================== WARNING: possible circular locking dependency detected 6.1.141-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor/5286 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_d46ba5bef82912c0+0x3d/0x41 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_release+0x593/0x910 kernel/locking/lockdep.c:5686 __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] free_unref_page+0x195/0x3f0 mm/page_alloc.c:3503 __vunmap+0x856/0xa00 mm/vmalloc.c:2718 kcov_put kernel/kcov.c:437 [inline] kcov_close+0x27/0x50 kernel/kcov.c:533 __fput+0x22c/0x920 fs/file_table.c:320 task_work_run+0x1ca/0x250 kernel/task_work.c:203 exit_task_work include/linux/task_work.h:39 [inline] do_exit+0x936/0x2400 kernel/exit.c:871 do_group_exit+0x217/0x2d0 kernel/exit.c:1021 __do_sys_exit_group kernel/exit.c:1032 [inline] __se_sys_exit_group kernel/exit.c:1030 [inline] __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1030 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 syz-executor/5286: #0: ffffc900001e0bc0 ((&dsp_spl_tl)){+.-.}-{0:0}, at: call_timer_fn+0xc1/0x670 kernel/time/timer.c:1501 #1: ffffffff8d8c9cf8 (dsp_lock){..-.}-{2:2}, at: dsp_cmx_send+0x22/0x1b30 drivers/isdn/mISDN/dsp_cmx.c:1643 #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: 5286 Comm: syz-executor Not tainted 6.1.141-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: 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_d46ba5bef82912c0+0x3d/0x41 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 RIP: 0010:lock_release+0x593/0x910 kernel/locking/lockdep.c:5686 Code: 00 00 00 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 75 75 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 66 43 c7 44 2f 09 00 00 43 c6 44 2f 0b 00 RSP: 0018:ffffc9000355f9e0 EFLAGS: 00000206 RAX: 0000000000000001 RBX: ffffffffffffffff RCX: ce509ff8d705bb00 RDX: 0000000000000000 RSI: ffffffff8a6c1160 RDI: ffffffff8abf1360 RBP: ffffc9000355fae8 R08: dffffc0000000000 R09: fffffbfff1bfd0b6 R10: fffffbfff1bfd0b6 R11: 1ffffffff1bfd0b5 R12: ffff88802c544660 R13: dffffc0000000000 R14: ffff88802c544650 R15: 1ffff920006abf48 __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] free_unref_page+0x195/0x3f0 mm/page_alloc.c:3503 __vunmap+0x856/0xa00 mm/vmalloc.c:2718 kcov_put kernel/kcov.c:437 [inline] kcov_close+0x27/0x50 kernel/kcov.c:533 __fput+0x22c/0x920 fs/file_table.c:320 task_work_run+0x1ca/0x250 kernel/task_work.c:203 exit_task_work include/linux/task_work.h:39 [inline] do_exit+0x936/0x2400 kernel/exit.c:871 do_group_exit+0x217/0x2d0 kernel/exit.c:1021 __do_sys_exit_group kernel/exit.c:1032 [inline] __se_sys_exit_group kernel/exit.c:1030 [inline] __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1030 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: 0033:0x7f1c6398e929 Code: Unable to access opcode bytes at 0x7f1c6398e8ff. RSP: 002b:00007ffed2440f98 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000043 RCX: 00007f1c6398e929 RDX: 00007f1c6398d3a0 RSI: 0000000000000004 RDI: 0000000000000043 RBP: 00007f1c63bb6738 R08: 00007ffed243ed36 R09: 0000000000000008 R10: 000000000000001a R11: 0000000000000246 R12: 0000000000000008 R13: 0000000000000003 R14: 0000000000000009 R15: 0000000000000000 ---------------- Code disassembly (best guess): 0: 00 00 add %al,(%rax) 2: 00 00 add %al,(%rax) 4: 9c pushf 5: 8f 84 24 80 00 00 00 pop 0x80(%rsp) c: f6 84 24 81 00 00 00 testb $0x2,0x81(%rsp) 13: 02 14: 75 75 jne 0x8b 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: 66 43 c7 44 2f 09 00 movw $0x0,0x9(%r15,%r13,1) 39: 00 3a: 43 c6 44 2f 0b 00 movb $0x0,0xb(%r15,%r13,1)