====================================================== WARNING: possible circular locking dependency detected 6.6.96-syzkaller #0 Not tainted ------------------------------------------------------ kworker/u4:0/11 is trying to acquire lock: ffff8880b8f295a8 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:2955 [inline] ffff8880b8f295a8 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3364 [inline] ffff8880b8f295a8 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3449 but task is already holding lock: ffff8880b8f297d8 (&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:3477 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:3793 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:2955 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3364 [inline] kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3449 trie_delete_elem+0x535/0x6a0 kernel/bpf/lpm_trie.c:545 bpf_prog_2c29ac5cdc6b1842+0x42/0x46 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 filter_irq_stacks+0x6c/0x90 kernel/stacktrace.c:395 __stack_depot_save+0x1f/0x630 lib/stackdepot.c:377 kasan_save_stack+0x4d/0x60 mm/kasan/common.c:46 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492 __call_rcu_common kernel/rcu/tree.c:2717 [inline] call_rcu+0x14f/0x920 kernel/rcu/tree.c:2833 kernfs_put+0x1d3/0x360 fs/kernfs/dir.c:578 kernfs_remove_by_name_ns+0xe4/0x150 fs/kernfs/dir.c:1696 kernfs_remove_by_name include/linux/kernfs.h:624 [inline] remove_files fs/sysfs/group.c:28 [inline] sysfs_remove_group+0xfc/0x2a0 fs/sysfs/group.c:292 sysfs_remove_groups+0x54/0xa0 fs/sysfs/group.c:316 device_remove_groups drivers/base/core.c:2792 [inline] device_remove_attrs+0x209/0x260 drivers/base/core.c:2973 device_del+0x503/0x900 drivers/base/core.c:3871 unregister_netdevice_many_notify+0x135e/0x1810 net/core/dev.c:11104 unregister_netdevice_many net/core/dev.c:11130 [inline] default_device_exit_batch+0x9cb/0xa60 net/core/dev.c:11608 ops_exit_list net/core/net_namespace.c:178 [inline] cleanup_net+0x77f/0xb90 net/core/net_namespace.c:652 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 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 *** 9 locks held by kworker/u4:0/11: #0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711 #1: ffffc90000107d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #1: ffffc90000107d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711 #2: ffffffff8dfae950 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x136/0xb90 net/core/net_namespace.c:606 #3: ffffffff8dfbb748 (rtnl_mutex){+.+.}-{3:3}, at: default_device_exit_batch+0xe9/0xa60 net/core/dev.c:11594 #4: ffff88801967f948 (&root->kernfs_rwsem){++++}-{3:3}, at: kernfs_remove_by_name_ns+0x7c/0x150 fs/kernfs/dir.c:1690 #5: ffffc900001f0c00 ((&dsp_spl_tl)){+.-.}-{0:0}, at: call_timer_fn+0xbf/0x530 kernel/time/timer.c:1697 #6: ffffffff8dd22d58 (dsp_lock){..-.}-{2:2}, at: dsp_cmx_send+0x26/0x1b40 drivers/isdn/mISDN/dsp_cmx.c:1632 #7: ffff8880b8f297d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:999 #8: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #8: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #8: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2321 [inline] #8: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run3+0xf4/0x400 kernel/trace/bpf_trace.c:2362 stack backtrace: CPU: 1 PID: 11 Comm: kworker/u4:0 Not tainted 6.6.96-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: netns cleanup_net Call Trace: 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:2955 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3364 [inline] kvfree_call_rcu+0x15a/0x780 kernel/rcu/tree.c:3449 trie_delete_elem+0x535/0x6a0 kernel/bpf/lpm_trie.c:545 bpf_prog_2c29ac5cdc6b1842+0x42/0x46 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 RIP: 0010:filter_irq_stacks+0x6c/0x90 kernel/stacktrace.c:394 Code: e0 01 80 8a 0f 93 c1 48 3d f0 15 80 8a 0f 92 c2 84 d1 75 27 48 3d d0 37 78 8a 0f 92 c1 48 3d db 37 78 8a 0f 93 c0 08 c8 74 11 <48> ff c3 49 83 c7 08 49 39 dc 75 ae 44 89 e3 eb 06 ff c3 eb 02 31 RSP: 0018:ffffc900001070f8 EFLAGS: 00000202 RAX: ffffffff886c2101 RBX: 0000000000000009 RCX: 0000000000000001 RDX: 0000000000000001 RSI: 0000000000000011 RDI: ffffc90000107180 RBP: 0000000000000000 R08: ffff888019e7bc00 R09: 0000000000000002 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000011 R13: dffffc0000000000 R14: ffffc90000107180 R15: ffffc900001071c8 __stack_depot_save+0x1f/0x630 lib/stackdepot.c:377 kasan_save_stack+0x4d/0x60 mm/kasan/common.c:46 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492 __call_rcu_common kernel/rcu/tree.c:2717 [inline] call_rcu+0x14f/0x920 kernel/rcu/tree.c:2833 kernfs_put+0x1d3/0x360 fs/kernfs/dir.c:578 kernfs_remove_by_name_ns+0xe4/0x150 fs/kernfs/dir.c:1696 kernfs_remove_by_name include/linux/kernfs.h:624 [inline] remove_files fs/sysfs/group.c:28 [inline] sysfs_remove_group+0xfc/0x2a0 fs/sysfs/group.c:292 sysfs_remove_groups+0x54/0xa0 fs/sysfs/group.c:316 device_remove_groups drivers/base/core.c:2792 [inline] device_remove_attrs+0x209/0x260 drivers/base/core.c:2973 device_del+0x503/0x900 drivers/base/core.c:3871 unregister_netdevice_many_notify+0x135e/0x1810 net/core/dev.c:11104 unregister_netdevice_many net/core/dev.c:11130 [inline] default_device_exit_batch+0x9cb/0xa60 net/core/dev.c:11608 ops_exit_list net/core/net_namespace.c:178 [inline] cleanup_net+0x77f/0xb90 net/core/net_namespace.c:652 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 ---------------- Code disassembly (best guess): 0: e0 01 loopne 0x3 2: 80 8a 0f 93 c1 48 3d orb $0x3d,0x48c1930f(%rdx) 9: f0 15 80 8a 0f 92 lock adc $0x920f8a80,%eax f: c2 84 d1 ret $0xd184 12: 75 27 jne 0x3b 14: 48 3d d0 37 78 8a cmp $0xffffffff8a7837d0,%rax 1a: 0f 92 c1 setb %cl 1d: 48 3d db 37 78 8a cmp $0xffffffff8a7837db,%rax 23: 0f 93 c0 setae %al 26: 08 c8 or %cl,%al 28: 74 11 je 0x3b * 2a: 48 ff c3 inc %rbx <-- trapping instruction 2d: 49 83 c7 08 add $0x8,%r15 31: 49 39 dc cmp %rbx,%r12 34: 75 ae jne 0xffffffe4 36: 44 89 e3 mov %r12d,%ebx 39: eb 06 jmp 0x41 3b: ff c3 inc %ebx 3d: eb 02 jmp 0x41 3f: 31 .byte 0x31