rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (2 ticks this GP) idle=767c/1/0x4000000000000000 softirq=15260/15260 fqs=0 rcu: (detected by 0, t=10506 jiffies, g=12605, q=384 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 6080 Comm: syz-executor.0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 RIP: 0010:__this_cpu_preempt_check+0x0/0x20 lib/smp_processor_id.c:63 Code: d1 27 8c e8 f2 2d 78 f5 e8 8d 74 83 f5 eb aa 66 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 0f 1e fa 48 89 fe 48 c7 c7 00 d1 27 8c e9 fd fe ff ff cc cc cc RSP: 0018:ffffc90000a08bf0 EFLAGS: 00000046 RAX: 4c89bcc34f22e702 RBX: 0000000000000006 RCX: 0000000000010203 RDX: 0000000000000002 RSI: ffff88802fe7a2c0 RDI: ffffffff8e16b69a RBP: ffff8880328fe728 R08: ffff88806c50c487 R09: 1ffff1100d8a1890 R10: dffffc0000000000 R11: ffffed100d8a1891 R12: 0000000000000002 R13: 0000000000000002 R14: ffff88802fe7a2c0 R15: ffff8880328fdb80 FS: 00007f0f7c7d66c0(0000) GS:ffff888125557000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f0f7bba8000 CR3: 0000000042a44000 CR4: 00000000003526f0 Call Trace: lockdep_recursion_finish kernel/locking/lockdep.c:470 [inline] lock_release+0x259/0x3d0 kernel/locking/lockdep.c:5891 __raw_spin_unlock include/linux/spinlock_api_smp.h:167 [inline] _raw_spin_unlock+0x16/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:389 [inline] advance_sched+0x99f/0xc90 net/sched/sch_taprio.c:987 __run_hrtimer kernel/time/hrtimer.c:1785 [inline] __hrtimer_run_queues+0x53a/0xcc0 kernel/time/hrtimer.c:1849 hrtimer_interrupt+0x42b/0x1010 kernel/time/hrtimer.c:1911 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x102/0x460 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:194 Code: f7 e8 dd 21 f0 f5 f7 c3 00 02 00 00 74 05 e8 70 8d 1b f6 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 a4 de e1 f5 65 8b 05 0d 80 6a 07 85 c0 74 18 5b 41 5e c3 cc cc RSP: 0018:ffffc900049a6e88 EFLAGS: 00000206 RAX: 0000000000000006 RBX: 0000000000000282 RCX: 0000000000000202 RDX: 0000000000000002 RSI: ffffffff8defadf3 RDI: 0000000000000001 RBP: ffffc900049a7170 R08: ffffffff9011cfb7 R09: 1ffffffff20239f6 R10: dffffc0000000000 R11: fffffbfff20239f7 R12: ffff88802fe7a290 R13: dffffc0000000000 R14: ffff88802fe7a2a8 R15: ffff88802fe7a2f8 spin_unlock_irqrestore include/linux/spinlock.h:407 [inline] taprio_change+0x30fe/0x3e50 net/sched/sch_taprio.c:1985 taprio_init+0x96f/0xbe0 net/sched/sch_taprio.c:2124 qdisc_create+0x7c4/0xf20 net/sched/sch_api.c:1319 __tc_modify_qdisc net/sched/sch_api.c:1753 [inline] tc_modify_qdisc+0x16f0/0x2290 net/sched/sch_api.c:1817 rtnetlink_rcv_msg+0x77e/0xbe0 net/core/rtnetlink.c:7003 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x972/0x9f0 net/socket.c:2592 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2646 __sys_sendmsg net/socket.c:2678 [inline] __do_sys_sendmsg net/socket.c:2683 [inline] __se_sys_sendmsg net/socket.c:2681 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2681 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f0f7ba6e3b9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 d0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f0f7c7d6078 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f0f7bbabf80 RCX: 00007f0f7ba6e3b9 RDX: 0000000000000000 RSI: 00000000200007c0 RDI: 0000000000000004 RBP: 00007f0f7bacf498 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007f0f7bbabf80 R15: 00007ffd31fa74e8 rcu: rcu_preempt kthread starved for 10506 jiffies! g12605 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:27656 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0x15dd/0x52d0 kernel/sched/core.c:6911 __schedule_loop kernel/sched/core.c:6993 [inline] schedule+0x164/0x360 kernel/sched/core.c:7008 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+0x51e/0xb90 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: 0 UID: 0 PID: 5489 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xce5/0x12c0 kernel/smp.c:877 Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 d4 eb 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 7f e7 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 63 e7 RSP: 0018:ffffc900035f7560 EFLAGS: 00000293 RAX: ffffffff81b9cd6d RBX: 1ffff110170e813d RCX: ffff888027811e80 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900035f76a0 R08: ffffffff9011cfb7 R09: 1ffffffff20239f6 R10: dffffc0000000000 R11: fffffbfff20239f7 R12: ffff8880b87409e8 R13: dffffc0000000000 R14: ffff8880b863c000 R15: 0000000000000001 FS: 00007fc666d88780(0000) GS:ffff888125457000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc666cc6ff8 CR3: 000000007959a000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1043 __flush_tlb_multi arch/x86/include/asm/paravirt.h:57 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1382 [inline] flush_tlb_mm_range+0x5c3/0x10c0 arch/x86/mm/tlb.c:1472 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:505 [inline] tlb_flush_mmu+0x1af/0xa30 mm/mmu_gather.c:404 tlb_finish_mmu+0xf9/0x230 mm/mmu_gather.c:530 unmap_region+0x2a5/0x330 mm/vma.c:488 vms_clear_ptes mm/vma.c:1284 [inline] vms_complete_munmap_vmas+0x493/0xc60 mm/vma.c:1326 do_vmi_align_munmap+0x3b7/0x4b0 mm/vma.c:1585 do_vmi_munmap+0x252/0x2d0 mm/vma.c:1633 __vm_munmap+0x22c/0x3d0 mm/vma.c:3254 __do_sys_munmap mm/mmap.c:1078 [inline] __se_sys_munmap mm/mmap.c:1075 [inline] __x64_sys_munmap+0x60/0x70 mm/mmap.c:1075 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc666e89097 Code: 73 01 c3 48 8b 0d 61 2d 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 0b 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 31 2d 0d 00 f7 d8 64 89 01 48 RSP: 002b:00007ffebca1ed18 EFLAGS: 00000202 ORIG_RAX: 000000000000000b RAX: ffffffffffffffda RBX: 0000000000009000 RCX: 00007fc666e89097 RDX: 00007fc666e76dd0 RSI: 0000000000009000 RDI: 00007fc666cbe000 RBP: 00007fc666cbe000 R08: 00000000000017c1 R09: 0000000000000000 R10: 0000000000000008 R11: 0000000000000202 R12: 0000000000000000 R13: 00007ffebca1ed50 R14: 0000000000000001 R15: 00007fc666e76dd0 hrtimer: interrupt took 109080596325 ns