rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=b4d4/1/0x4000000000000000 softirq=40518/40519 fqs=2 rcu: (detected by 1, t=10502 jiffies, g=39049, q=114 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 11110 Comm: syz.3.1640 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:check_preemption_disabled+0x25/0x120 lib/smp_processor_id.c:16 Code: 90 90 90 90 90 55 41 57 41 56 53 48 83 ec 10 65 48 8b 05 de b4 27 07 48 89 44 24 08 65 8b 05 e6 b4 27 07 65 8b 0d db b4 27 07 c1 ff ff ff 7f 74 23 65 48 8b 0d bb b4 27 07 48 3b 4c 24 08 0f RSP: 0018:ffffc90000007bb0 EFLAGS: 00000082 RAX: 0000000000000000 RBX: ffffffff89602478 RCX: 0000000080010002 RDX: 0000000000010000 RSI: ffffffff8bbf08c0 RDI: ffffffff8bbf0880 RBP: 0000000000000001 R08: ffff8880583b015f R09: 1ffff1100b07602b R10: dffffc0000000000 R11: ffffed100b07602c R12: ffff8880583b0360 R13: ffffffff89602478 R14: ffffffff8df3d6e0 R15: ffff88807de41000 FS: 000055558de6f500(0000) GS:ffff88812613b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9301ddcf98 CR3: 000000002fe27000 CR4: 0000000000350ef0 Call Trace: rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] rcu_is_watching+0x15/0xb0 kernel/rcu/tree.c:751 trace_lock_release include/trace/events/lock.h:69 [inline] lock_release+0x4b/0x3e0 kernel/locking/lockdep.c:5879 rcu_lock_release include/linux/rcupdate.h:341 [inline] rcu_read_unlock include/linux/rcupdate.h:897 [inline] advance_sched+0xb23/0xc90 net/sched/sch_taprio.c:992 __run_hrtimer kernel/time/hrtimer.c:1777 [inline] __hrtimer_run_queues+0x52c/0xc60 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline] __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1058 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:finish_task_switch+0x26b/0x950 kernel/sched/core.c:5193 Code: 0f 84 3c 01 00 00 48 85 db 0f 85 63 01 00 00 e9 27 05 00 00 4c 8b 75 d0 4c 89 e7 e8 3f 0d b8 09 e8 7a b9 36 00 fb 4c 8b 65 c0 <49> 8d bc 24 58 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0 RSP: 0018:ffffc9000f1677b8 EFLAGS: 00000286 RAX: 2a2061c8b2749500 RBX: 0000000000000000 RCX: 2a2061c8b2749500 RDX: 0000000000000000 RSI: ffffffff8d70e34e RDI: ffffffff8bbf08e0 RBP: ffffc9000f167810 R08: ffffffff8f7ced77 R09: 1ffffffff1ef9dae R10: dffffc0000000000 R11: fffffbfff1ef9daf R12: ffff88807ddfdac0 R13: dffffc0000000000 R14: ffff88802e599e40 R15: ffff8880b883abd8 context_switch kernel/sched/core.c:5328 [inline] __schedule+0x17a0/0x4cc0 kernel/sched/core.c:6929 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7113 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7137 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 class_preempt_destructor include/linux/preempt.h:470 [inline] try_to_wake_up+0x82b/0x12b0 kernel/sched/core.c:4300 wake_up_process kernel/sched/core.c:4424 [inline] wake_up_q+0x85/0xd0 kernel/sched/core.c:1086 futex_wake+0x4a0/0x560 kernel/futex/waitwake.c:198 do_futex+0x395/0x420 kernel/futex/syscalls.c:135 __do_sys_futex kernel/futex/syscalls.c:207 [inline] __se_sys_futex+0x36f/0x400 kernel/futex/syscalls.c:188 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9300f8f749 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:00007ffec15d8d18 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: ffffffffffffffda RBX: 00007f93011e5fa8 RCX: 00007f9300f8f749 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f93011e5fa8 RBP: 0000000000000000 R08: 00007ffec15d8bb7 R09: 00000001c15d900f R10: 00007f93011e5fa0 R11: 0000000000000246 R12: 00007f93011e5fac R13: 00007f93011e5fa0 R14: 00000000000000f0 R15: 0000000000000002 rcu: rcu_preempt kthread starved for 10498 jiffies! g39049 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:26464 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 __schedule_loop kernel/sched/core.c:7011 [inline] schedule+0x165/0x360 kernel/sched/core.c:7026 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+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 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: 11111 Comm: syz.0.1639 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 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 e6 73 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 91 6f 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 75 6f RSP: 0018:ffffc9000c52f480 EFLAGS: 00000293 RAX: ffffffff81b4944b RBX: 1ffff11017108441 RCX: ffff888055515ac0 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000c52f600 R08: ffffffff8f7ced77 R09: 1ffffffff1ef9dae R10: dffffc0000000000 R11: fffffbfff1ef9daf R12: ffff8880b8842208 R13: dffffc0000000000 R14: ffff8880b893b240 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88812623b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f48e4bb7198 CR3: 000000005c140000 CR4: 0000000000350ef0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1043 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1381 [inline] flush_tlb_mm_range+0x6b1/0x12d0 arch/x86/mm/tlb.c:1471 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:490 [inline] tlb_flush_mmu+0x1a7/0x680 mm/mmu_gather.c:403 tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:497 exit_mmap+0x444/0xb40 mm/mmap.c:1293 __mmput+0x118/0x430 kernel/fork.c:1133 exit_mm+0x1da/0x2c0 kernel/exit.c:582 do_exit+0x648/0x2300 kernel/exit.c:954 do_group_exit+0x21c/0x2d0 kernel/exit.c:1107 get_signal+0x1285/0x1340 kernel/signal.c:3034 arch_do_signal_or_restart+0xa0/0x790 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x72/0x130 kernel/entry/common.c:40 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f0206f8f749 Code: Unable to access opcode bytes at 0x7f0206f8f71f. RSP: 002b:00007f0207efe0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 00007f02071e5fa8 RCX: 00007f0206f8f749 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f02071e5fac RBP: 00007f02071e5fa0 R08: 3fffffffffffffff R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000 R13: 00007f02071e6038 R14: 00007ffca87cd570 R15: 00007ffca87cd658