rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P25418/1:b..l rcu: (detected by 1, t=10503 jiffies, g=240805, q=2098 ncpus=2) task:syz.5.14526 state:R running task stack:26920 pid:25418 tgid:25409 ppid:22384 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5504 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7228 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7552 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:batadv_hardif_get_by_netdev+0x165/0x3f0 net/batman-adv/hard-interface.c:84 Code: 29 28 0f 49 81 ff 40 cb 99 9a 0f 84 bb 01 00 00 4c 89 74 24 10 4c 89 6c 24 08 49 8d 5f 18 48 89 d8 48 c1 e8 03 42 80 3c 20 00 <74> 08 48 89 df e8 b1 a8 bf f6 4c 39 33 74 0a e8 07 54 54 f6 e9 03 RSP: 0018:ffffc90005f27720 EFLAGS: 00000246 RAX: 1ffff110082f1e03 RBX: ffff88804178f018 RCX: ffff8880b3848000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90005f277d0 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: fffffbfff1fba375 R12: dffffc0000000000 R13: 1ffff92000be4ee8 R14: ffff8880781a4000 R15: ffff88804178f000 batadv_hard_if_event+0x1226/0x3520 net/batman-adv/hard-interface.c:1108 notifier_call_chain+0x1a5/0x3d0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2288 [inline] call_netdevice_notifiers net/core/dev.c:2302 [inline] register_netdevice+0x18a4/0x1eb0 net/core/dev.c:11477 register_netdev+0x40/0x60 net/core/dev.c:11555 loopback_net_init+0x75/0x150 drivers/net/loopback.c:218 ops_init+0x35d/0x5d0 net/core/net_namespace.c:137 setup_net+0x118/0x350 net/core/net_namespace.c:446 copy_net_ns+0x4f9/0x720 net/core/net_namespace.c:579 create_new_namespaces+0x3f0/0x6b0 kernel/nsproxy.c:132 unshare_nsproxy_namespaces+0x149/0x190 kernel/nsproxy.c:234 ksys_unshare+0x57d/0xa00 kernel/fork.c:3266 __do_sys_unshare kernel/fork.c:3340 [inline] __se_sys_unshare kernel/fork.c:3338 [inline] __x64_sys_unshare+0x38/0x50 kernel/fork.c:3338 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7f07f9ce59 RSP: 002b:00007f7f08d9a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 00007f7f08216180 RCX: 00007f7f07f9ce59 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000006a040000 RBP: 00007f7f08032e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f7f08216218 R14: 00007f7f08216180 R15: 00007ffe9b2ba918 rcu: rcu_preempt kthread starved for 5398 jiffies! g240805 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:R running task stack:28040 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5504 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7228 __schedule_loop kernel/sched/core.c:7307 [inline] schedule+0x164/0x360 kernel/sched/core.c:7322 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 UID: 0 PID: 14320 Comm: kworker/u9:1 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: hci0 hci_cmd_work RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] RIP: 0010:rcu_is_watching+0x10/0xb0 kernel/rcu/tree.c:752 Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 57 41 56 53 65 ff 05 40 56 8f 11 fb 07 fd 09 89 c3 83 f8 08 73 65 49 bf 00 00 00 00 00 fc ff df RSP: 0018:ffffc90000a07a00 EFLAGS: 00000283 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e959a20 RBP: ffffffff8176a21f R08: 0000000000000000 R09: 0000000000000000 R10: ffffc90000a07bb8 R11: ffffffff81b10630 R12: 0000000000000002 R13: ffffffff8e959a20 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88812537c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007feee24b5e80 CR3: 00000000365ec000 CR4: 00000000003526f0 Call Trace: trace_lock_acquire include/trace/events/lock.h:23 [inline] lock_acquire+0x5f/0x350 kernel/locking/lockdep.c:5831 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:840 [inline] class_rcu_constructor include/linux/rcupdate.h:1183 [inline] unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2700 [inline] slab_free mm/slub.c:6310 [inline] kmem_cache_free+0x182/0x650 mm/slub.c:6437 kfree_skb_reason include/linux/skbuff.h:1325 [inline] kfree_skb include/linux/skbuff.h:1334 [inline] ip6_mc_input+0x909/0xbc0 net/ipv6/ip6_input.c:638 ip_sabotage_in+0x1e1/0x270 net/bridge/br_netfilter_hooks.c:988 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK+0x21f/0x3c0 include/linux/netfilter.h:316 __netif_receive_skb_one_core net/core/dev.c:6206 [inline] __netif_receive_skb net/core/dev.c:6319 [inline] netif_receive_skb_internal net/core/dev.c:6405 [inline] netif_receive_skb+0x278/0xbf0 net/core/dev.c:6464 NF_HOOK+0xa4/0x3a0 include/linux/netfilter.h:318 br_handle_frame_finish+0x1192/0x1990 net/bridge/br_input.c:-1 br_nf_hook_thresh+0x3dd/0x4c0 net/bridge/br_netfilter_hooks.c:-1 br_nf_pre_routing_finish_ipv6+0x90c/0xc40 net/bridge/br_netfilter_ipv6.c:-1 NF_HOOK include/linux/netfilter.h:318 [inline] br_nf_pre_routing_ipv6+0x382/0x6f0 net/bridge/br_netfilter_ipv6.c:183 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_bridge_pre net/bridge/br_input.c:291 [inline] br_handle_frame+0x127f/0x1510 net/bridge/br_input.c:442 __netif_receive_skb_core+0x989/0x30b0 net/core/dev.c:6093 __netif_receive_skb_one_core net/core/dev.c:6204 [inline] __netif_receive_skb net/core/dev.c:6319 [inline] process_backlog+0x706/0x1860 net/core/dev.c:6670 __napi_poll+0xaa/0x330 net/core/dev.c:7729 napi_poll net/core/dev.c:7792 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:7949 handle_softirqs+0x225/0x840 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:arch_try_cmpxchg128 arch/x86/include/asm/cmpxchg_64.h:83 [inline] RIP: 0010:__update_freelist_fast mm/slub.c:652 [inline] RIP: 0010:slab_update_freelist mm/slub.c:718 [inline] RIP: 0010:__slab_free+0xbd/0x2c0 mm/slub.c:5623 Code: 44 24 04 74 45 85 c0 74 41 45 31 e4 41 f6 46 0a 20 74 66 48 8b 44 24 40 48 8b 54 24 48 48 89 de 48 8b 5c 24 30 48 8b 4c 24 38 48 0f c7 4e 20 48 89 f3 0f 84 e8 00 00 00 48 89 44 24 40 48 89 RSP: 0018:ffffc900058678f0 EFLAGS: 00000202 RAX: ffff88803cfa6100 RBX: ffff88803cfa6000 RCX: 0000000800100001 RDX: 0000000800100002 RSI: ffffea0000f3e980 RDI: ffff888140412140 RBP: ffffc90005867978 R08: 0000000000000000 R09: ffffffff82315cae R10: dffffc0000000000 R11: fffffbfff20622ff R12: 0000000000000000 R13: ffff88803cfa6100 R14: ffff888140412140 R15: 0000000000000000 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4610 [inline] slab_alloc_node mm/slub.c:4939 [inline] kmem_cache_alloc_noprof+0x2b8/0x650 mm/slub.c:4946 skb_clone+0x212/0x3a0 net/core/skbuff.c:2110 hci_send_cmd_sync net/bluetooth/hci_core.c:4072 [inline] hci_cmd_work+0xc2/0x780 net/bluetooth/hci_core.c:4115 process_one_work kernel/workqueue.c:3314 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3397 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3478 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 net_ratelimit: 17305 callbacks suppressed bridge0: received packet on veth1_to_bridge with own address as source address (addr:b6:2b:c6:39:2a:b1, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:b6:2b:c6:39:2a:b1, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:b6:2b:c6:39:2a:b1, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:b6:2b:c6:39:2a:b1, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:b6:2b:c6:39:2a:b1, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:b6:2b:c6:39:2a:b1, vlan:0) net_ratelimit: 30991 callbacks suppressed bridge0: received packet on veth1_to_bridge with own address as source address (addr:b6:2b:c6:39:2a:b1, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:b6:2b:c6:39:2a:b1, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:b6:2b:c6:39:2a:b1, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:b6:2b:c6:39:2a:b1, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:b6:2b:c6:39:2a:b1, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:b6:2b:c6:39:2a:b1, vlan:0)