rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P27354/1:b..l rcu: (detected by 1, t=10503 jiffies, g=137117, q=1943 ncpus=2) task:syz.1.6002 state:R running task stack:26656 pid:27354 tgid:27344 ppid:17528 task_flags:0x400040 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x17b4/0x5680 kernel/sched/core.c:7189 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7370 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __local_bh_enable_ip+0xe1/0x130 kernel/softirq.c:457 nl80211_netlink_notify+0x46b/0x840 net/wireless/nl80211.c:22542 notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85 blocking_notifier_call_chain+0x6a/0x90 kernel/notifier.c:380 netlink_release+0x123b/0x1ad0 net/netlink/af_netlink.c:761 __sock_release net/socket.c:722 [inline] sock_close+0xc3/0x240 net/socket.c:1514 __fput+0x44f/0xa60 fs/file_table.c:510 fput_close_sync+0x11f/0x240 fs/file_table.c:615 __do_sys_close fs/open.c:1507 [inline] __se_sys_close fs/open.c:1492 [inline] __x64_sys_close+0x7e/0x110 fs/open.c:1492 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7efd3c35d60e RSP: 002b:00007efd3d176f38 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: ffffffffffffffda RBX: 00007efd3d1786c0 RCX: 00007efd3c35d60e RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000007 RBP: 0000000000000007 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007efd3c616128 R14: 00007efd3c616090 R15: 00007ffd5a10aa58 rcu: rcu_preempt kthread starved for 1529 jiffies! g137117 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 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:28096 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x17b4/0x5680 kernel/sched/core.c:7189 __schedule_loop kernel/sched/core.c:7268 [inline] schedule+0x164/0x360 kernel/sched/core.c:7283 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297 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: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 2 Comm: kthreadd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:br_handle_vlan+0x4/0x530 net/bridge/br_vlan.c:484 Code: 07 38 c1 0f 8c 52 ff ff ff 4c 89 e7 e8 f5 d6 af f7 e9 45 ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 <55> 41 57 41 56 41 55 41 54 53 48 83 ec 20 48 89 cb 49 89 d4 48 89 RSP: 0018:ffffc90000007268 EFLAGS: 00000246 RAX: 1ffff1100f89bf00 RBX: ffff8880a8a9e140 RCX: ffff8880a8a9e140 RDX: ffff8880a86bb000 RSI: ffff88807c4df800 RDI: ffff88803008ce40 RBP: 0000000000000000 R08: ffff888032b92be3 R09: 1ffff1100657257c R10: dffffc0000000000 R11: ffffed100657257d R12: 0000000000000001 R13: ffff88807c4df800 R14: ffff8880a86bb000 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff88812528d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f362812fa90 CR3: 0000000035f82000 CR4: 00000000003526f0 Call Trace: __br_forward+0xbb/0x540 net/bridge/br_forward.c:87 deliver_clone net/bridge/br_forward.c:131 [inline] maybe_deliver net/bridge/br_forward.c:191 [inline] br_flood+0x6ee/0xb80 net/bridge/br_forward.c:238 br_handle_frame_finish+0x1521/0x1c80 net/bridge/br_input.c:229 br_nf_hook_thresh+0x3dd/0x4c0 net/bridge/br_netfilter_hooks.c:-1 br_nf_pre_routing_finish_ipv6+0x91f/0xc30 net/bridge/br_netfilter_ipv6.c:-1 NF_HOOK include/linux/netfilter.h:318 [inline] br_nf_pre_routing_ipv6+0x374/0x6f0 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+0x1277/0x1510 net/bridge/br_input.c:442 __netif_receive_skb_core+0x98f/0x3170 net/core/dev.c:6089 __netif_receive_skb_one_core net/core/dev.c:6200 [inline] __netif_receive_skb net/core/dev.c:6315 [inline] process_backlog+0x76d/0x1950 net/core/dev.c:6666 __napi_poll+0xae/0x340 net/core/dev.c:7733 napi_poll net/core/dev.c:7796 [inline] net_rx_action+0x627/0xf70 net/core/dev.c:7953 handle_softirqs+0x22a/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:1061 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_release+0x2d7/0x3c0 kernel/locking/lockdep.c:5893 Code: 93 97 11 00 00 00 00 eb b5 e8 b5 d2 06 0a f7 c3 00 02 00 00 74 b9 65 48 8b 05 a5 4d 97 11 48 3b 44 24 28 75 44 fb 48 83 c4 30 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 0a c5 09 0a cc 48 8d 3d a2 2f 92 RSP: 0018:ffffc90000077100 EFLAGS: 00000286 RAX: 750407705b0b6600 RBX: 0000000000000202 RCX: 0000000000000046 RDX: 0000000000000001 RSI: ffffffff8e219c55 RDI: ffffffff8c28ade0 RBP: ffff88801d6a4938 R08: ffffc90000077df8 R09: 0000000000000000 R10: ffffc90000077258 R11: fffff5200000ee4d R12: 0000000000000001 R13: 0000000000000001 R14: ffffffff8e95cd60 R15: ffff88801d6a3d80 rcu_lock_release include/linux/rcupdate.h:310 [inline] rcu_read_unlock include/linux/rcupdate.h:869 [inline] class_rcu_destructor include/linux/rcupdate.h:1181 [inline] unwind_next_frame+0x1bba/0x2550 arch/x86/kernel/unwind_orc.c:709 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 save_stack+0x122/0x230 mm/page_owner.c:165 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320 reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1402 [inline] __free_frozen_pages+0xbc7/0xd30 mm/page_alloc.c:2943 __slab_free+0x274/0x2c0 mm/slub.c:5612 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:4569 [inline] slab_alloc_node mm/slub.c:4898 [inline] kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4905 alloc_pid+0x1ae/0x1300 kernel/pid.c:188 copy_process+0x21d1/0x4440 kernel/fork.c:2280 kernel_clone+0x284/0x8f0 kernel/fork.c:2721 kernel_thread+0x13f/0x1b0 kernel/fork.c:2782 create_kthread kernel/kthread.c:459 [inline] kthreadd+0x4ec/0x6e0 kernel/kthread.c:817 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245