rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=1784/1/0x4000000000000000 softirq=18321/18321 fqs=142 rcu: (detected by 1, t=10502 jiffies, g=13465, q=350 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 6109 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 RIP: 0010:__netif_schedule+0x7a/0x2c0 net/core/dev.c:3375 Code: c1 ed 03 48 b8 f1 f1 f1 f1 00 f2 f2 f2 48 b9 00 00 00 00 00 fc ff df 49 89 44 0d 00 66 41 c7 44 0d 09 f3 f3 41 c6 44 0d 0b f3 71 32 5d f8 48 8d bb 58 01 00 00 be 08 00 00 00 e8 a0 a7 c0 f8 RSP: 0018:ffffc90000007b80 EFLAGS: 00000806 RAX: f2f2f200f1f1f1f1 RBX: ffff88807e794000 RCX: dffffc0000000000 RDX: 0000000000010000 RSI: ffffffff8be33e60 RDI: ffff88807e794000 RBP: ffffc90000007c60 R08: 0000000000000000 R09: ffffffff899b5638 R10: dffffc0000000000 R11: ffffed100fcf285e R12: ffff88807e794360 R13: 1ffff92000000f74 R14: 18656a822b6de01c R15: ffff888058dcb000 FS: 00007fa9b86ee6c0(0000) GS:ffff888125c15000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000600 CR3: 0000000032d44000 CR4: 00000000003526f0 Call Trace: advance_sched+0xa9a/0xc90 net/sched/sch_taprio.c:991 __run_hrtimer kernel/time/hrtimer.c:1761 [inline] __hrtimer_run_queues+0x529/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lockdep_unregister_key+0x2c5/0x310 kernel/locking/lockdep.c:6616 Code: 65 48 8b 05 4d 1d 03 11 48 3b 44 24 10 0f 84 26 fe ff ff e8 0d c4 dc 09 e8 38 c5 dc 09 41 f7 c7 00 02 00 00 74 bd fb 40 84 ed <75> bc eb cd 90 0f 0b 90 e9 19 ff ff ff 90 0f 0b 90 e9 2a ff ff ff RSP: 0018:ffffc90003abf088 EFLAGS: 00000246 RAX: f3c0b4823a3e7f00 RBX: ffff888030e54a98 RCX: f3c0b4823a3e7f00 RDX: ffffffff93647338 RSI: ffffffff8d9cd9ce RDI: ffffffff8be33e80 RBP: ffff888030e54a00 R08: 0000000000000000 R09: ffffffff81aa9548 R10: dffffc0000000000 R11: fffffbfff1f474a7 R12: 0000000000000000 R13: 0000000000001000 R14: 0000000000000000 R15: 0000000000000a07 __qdisc_destroy+0x166/0x420 net/sched/sch_generic.c:1083 taprio_attach+0x25a/0x380 net/sched/sch_taprio.c:2160 qdisc_graft+0x1175/0x1590 net/sched/sch_api.c:1162 __tc_modify_qdisc net/sched/sch_api.c:1756 [inline] tc_modify_qdisc+0x189b/0x20e0 net/sched/sch_api.c:1812 rtnetlink_rcv_msg+0x779/0xb70 net/core/rtnetlink.c:6955 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x82c/0x9e0 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg+0x219/0x270 net/socket.c:729 ____sys_sendmsg+0x505/0x830 net/socket.c:2614 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668 __sys_sendmsg net/socket.c:2700 [inline] __do_sys_sendmsg net/socket.c:2705 [inline] __se_sys_sendmsg net/socket.c:2703 [inline] __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2703 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa9b778eba9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fa9b86ee038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fa9b79d5fa0 RCX: 00007fa9b778eba9 RDX: 0000000000000000 RSI: 00002000000007c0 RDI: 0000000000000004 RBP: 00007fa9b7811e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fa9b79d6038 R14: 00007fa9b79d5fa0 R15: 00007fa9b7affa28 rcu: rcu_preempt kthread starved for 9790 jiffies! g13465 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:27432 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0x165/0x360 kernel/sched/core.c:7058 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x436/0x7d0 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: CPU: 1 UID: 0 PID: 5530 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xd33/0x12d0 kernel/smp.c:877 Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 56 63 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 01 5f 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 e5 5e RSP: 0018:ffffc900039ff540 EFLAGS: 00000293 RAX: ffffffff81b45e7b RBX: 1ffff110170c8341 RCX: ffff88802ea2da00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900039ff6c0 R08: ffffffff8fa3a537 R09: 1ffffffff1f474a6 R10: dffffc0000000000 R11: fffffbfff1f474a7 R12: ffff8880b8641a08 R13: dffffc0000000000 R14: ffff8880b873b1c0 R15: 0000000000000000 FS: 00007f389d950740(0000) GS:ffff888125d15000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005555830835c8 CR3: 00000000337a8000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1044 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x6b1/0x12d0 arch/x86/mm/tlb.c:1451 dup_mmap+0x15a0/0x1ac0 mm/mmap.c:1873 dup_mm kernel/fork.c:1485 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1537 copy_process+0x1706/0x3c00 kernel/fork.c:2175 kernel_clone+0x21e/0x840 kernel/fork.c:2605 __do_sys_clone kernel/fork.c:2748 [inline] __se_sys_clone kernel/fork.c:2732 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2732 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f389da24636 Code: 89 df e8 6d e8 f6 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffedda3b710 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffedda3b718 RCX: 00007f389da24636 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007ffedda5bc60 R08: 0000000000000000 R09: 0000000000000001 R10: 00007f389d950a10 R11: 0000000000000246 R12: 00007ffedda3b850 R13: 0000000000000000 R14: 0000000000000000 R15: 000055691e79bac0