rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (1 GPs behind) idle=6064/1/0x4000000000000000 softirq=26074/26081 fqs=201 rcu: (t=10502 jiffies g=17021 q=320 ncpus=2) rcu: rcu_preempt kthread starved for 10101 jiffies! g17021 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:27672 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:7058 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2285 kthread+0x3c2/0x780 kernel/kthread.c:463 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148 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: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:__sanitizer_cov_trace_pc+0x66/0x70 kernel/kcov.c:235 Code: 82 18 16 00 00 83 f8 02 75 20 48 8b 8a 20 16 00 00 8b 92 1c 16 00 00 48 8b 01 48 83 c0 01 48 39 d0 73 07 48 89 01 48 89 34 c1 cc cc cc cc 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90000006848 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 00000000000000f2 RCX: ffffffff81caf853 RDX: ffffffff8e2977c0 RSI: ffffffff81caf877 RDI: 0000000000000004 RBP: 0000000000000000 R08: 0000000000000004 R09: 00000000000000f2 R10: 00000000000000f2 R11: 0000000000000000 R12: ffffffff9228fece R13: dffffc0000000000 R14: 00000000000000f2 R15: ffffffffa0201a4c FS: 0000000000000000(0000) GS:ffff8881246b5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9a761639e6 CR3: 000000003564b000 CR4: 00000000003526f0 Call Trace: bpf_ksym_find+0x127/0x1c0 kernel/bpf/core.c:745 is_bpf_text_address+0x58/0x1a0 kernel/bpf/core.c:777 kernel_text_address kernel/extable.c:125 [inline] kernel_text_address+0x8d/0x100 kernel/extable.c:94 __kernel_text_address+0xd/0x40 kernel/extable.c:79 unwind_get_return_address+0x59/0xa0 arch/x86/kernel/unwind_orc.c:369 arch_stack_walk+0xa6/0x100 arch/x86/kernel/stacktrace.c:26 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:243 [inline] __kasan_slab_free+0x60/0x70 mm/kasan/common.c:275 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2422 [inline] slab_free mm/slub.c:4695 [inline] kmem_cache_free+0x2d1/0x4d0 mm/slub.c:4797 __skb_ext_put+0x102/0x2c0 net/core/skbuff.c:7153 __skb_ext_del+0xf3/0x340 net/core/skbuff.c:7120 skb_ext_del include/linux/skbuff.h:4929 [inline] nf_bridge_info_free net/bridge/br_netfilter_hooks.c:156 [inline] br_nf_dev_queue_xmit+0x7b7/0x2a80 net/bridge/br_netfilter_hooks.c:919 NF_HOOK include/linux/netfilter.h:318 [inline] NF_HOOK include/linux/netfilter.h:312 [inline] br_nf_post_routing+0x8e7/0x1190 net/bridge/br_netfilter_hooks.c:966 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xbb/0x200 net/netfilter/core.c:623 nf_hook+0x45e/0x780 include/linux/netfilter.h:273 NF_HOOK include/linux/netfilter.h:316 [inline] br_forward_finish+0xcd/0x130 net/bridge/br_forward.c:66 br_nf_hook_thresh+0x304/0x410 net/bridge/br_netfilter_hooks.c:1167 br_nf_forward_finish+0x66a/0xba0 net/bridge/br_netfilter_hooks.c:662 NF_HOOK include/linux/netfilter.h:318 [inline] NF_HOOK include/linux/netfilter.h:312 [inline] br_nf_forward_ip.part.0+0x609/0x810 net/bridge/br_netfilter_hooks.c:716 br_nf_forward_ip net/bridge/br_netfilter_hooks.c:676 [inline] br_nf_forward+0xf0f/0x1be0 net/bridge/br_netfilter_hooks.c:773 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xbb/0x200 net/netfilter/core.c:623 nf_hook+0x45e/0x780 include/linux/netfilter.h:273 NF_HOOK include/linux/netfilter.h:316 [inline] __br_forward+0x1be/0x5b0 net/bridge/br_forward.c:115 deliver_clone net/bridge/br_forward.c:131 [inline] br_flood+0x39c/0x650 net/bridge/br_forward.c:249 br_handle_frame_finish+0xf2d/0x1ca0 net/bridge/br_input.c:221 br_nf_hook_thresh+0x304/0x410 net/bridge/br_netfilter_hooks.c:1167 br_nf_pre_routing_finish_ipv6+0x76a/0xfb0 net/bridge/br_netfilter_ipv6.c:154 NF_HOOK include/linux/netfilter.h:318 [inline] br_nf_pre_routing_ipv6+0x3cd/0x8c0 net/bridge/br_netfilter_ipv6.c:184 br_nf_pre_routing+0x860/0x15b0 net/bridge/br_netfilter_hooks.c:508 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_bridge_pre net/bridge/br_input.c:283 [inline] br_handle_frame+0xad5/0x14b0 net/bridge/br_input.c:434 __netif_receive_skb_core.constprop.0+0xa22/0x48c0 net/core/dev.c:5878 __netif_receive_skb_one_core+0xb0/0x1e0 net/core/dev.c:5989 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6104 process_backlog+0x442/0x15e0 net/core/dev.c:6456 __napi_poll.constprop.0+0xb7/0x550 net/core/dev.c:7506 napi_poll net/core/dev.c:7569 [inline] net_rx_action+0xa9f/0xfe0 net/core/dev.c:7696 handle_softirqs+0x219/0x8e0 kernel/softirq.c:579 __do_softirq kernel/softirq.c:613 [inline] invoke_softirq kernel/softirq.c:453 [inline] __irq_exit_rcu+0x109/0x170 kernel/softirq.c:680 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82 Code: dc 61 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 53 c3 15 00 fb f4 8c 09 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffffff8e207e08 EFLAGS: 000002c2 RAX: 0000000001240d6b RBX: 0000000000000000 RCX: ffffffff8b944c29 RDX: 0000000000000000 RSI: ffffffff8de522e0 RDI: ffffffff8c162d80 RBP: fffffbfff1c52ef8 R08: 0000000000000001 R09: ffffed1017086655 R10: ffff8880b84332ab R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff8e2977c0 R14: ffffffff90ab6b90 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:757 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:190 [inline] do_idle+0x391/0x510 kernel/sched/idle.c:330 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428 rest_init+0x16b/0x2b0 init/main.c:744 start_kernel+0x3ee/0x4d0 init/main.c:1097 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:307 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:288 common_startup_64+0x13e/0x148 CPU: 1 UID: 0 PID: 1298 Comm: aoe_tx0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194 Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 26 ce 00 f6 48 89 df e8 0e 22 01 f6 f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 01 00 00 00 e8 e5 1e f1 f5 65 8b 05 be bb 3f 08 85 c0 74 16 5b RSP: 0018:ffffc9000455f968 EFLAGS: 00000246 RAX: 0000000000000002 RBX: ffffffff9b115ba0 RCX: 0000000000000002 RDX: 0000000000000000 RSI: ffffffff8de522e0 RDI: ffffffff8c162d80 RBP: 0000000000000293 R08: 0000000000000001 R09: 0000000000000001 R10: ffffffff90ab6b97 R11: 0000000000000000 R12: ffffffff8f2ed540 R13: ffffffff9b115ca8 R14: 0000000000000000 R15: ffffffff9b115ce0 FS: 0000000000000000(0000) GS:ffff8881247b5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000003480 CR3: 000000007e818000 CR4: 00000000003526f0 Call Trace: spin_unlock_irqrestore include/linux/spinlock.h:406 [inline] uart_port_unlock_irqrestore include/linux/serial_core.h:788 [inline] uart_port_unlock_deref drivers/tty/serial/serial_core.c:91 [inline] uart_port_unlock_deref drivers/tty/serial/serial_core.c:88 [inline] uart_write_room+0x2d9/0x940 drivers/tty/serial/serial_core.c:650 tty_write_room+0x66/0x90 drivers/tty/tty_ioctl.c:69 handle_tx+0x14f/0x630 drivers/net/caif/caif_serial.c:212 __netdev_start_xmit include/linux/netdevice.h:5222 [inline] netdev_start_xmit include/linux/netdevice.h:5231 [inline] xmit_one net/core/dev.c:3839 [inline] dev_hard_start_xmit+0x94/0x740 net/core/dev.c:3855 __dev_queue_xmit+0xa46/0x4490 net/core/dev.c:4725 dev_queue_xmit include/linux/netdevice.h:3361 [inline] tx+0xcc/0x190 drivers/block/aoe/aoenet.c:62 kthread+0x1e4/0x3e0 drivers/block/aoe/aoecmd.c:1241 kthread+0x3c2/0x780 kernel/kthread.c:463 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 net_ratelimit: 8309 callbacks suppressed bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) net_ratelimit: 15124 callbacks suppressed bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)