rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=ab64/1/0x4000000000000000 softirq=101376/101376 fqs=0 rcu: (detected by 1, t=10505 jiffies, g=119061, q=1485 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 17161 Comm: dhcpcd-run-hook Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:210 Code: 89 fb e8 23 00 00 00 48 8b 3d 14 0e 89 0c 48 89 de 5b e9 63 01 62 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 48 8b 04 24 65 48 8b 0d b8 ed a5 11 65 8b 15 d9 ed a5 RSP: 0018:ffffc90000007dd0 EFLAGS: 00000097 RAX: ffffffff81b31096 RBX: 0000000000000000 RCX: 0000000000010000 RDX: ffff888044d58000 RSI: 0000000000000000 RDI: 0000000000000007 RBP: ffff888020b3c300 R08: ffff888020b3c19f R09: 1ffff11004167833 R10: dffffc0000000000 R11: ffffed1004167834 R12: ffff888044d58b88 R13: 0000000000000001 R14: ffff8880b8628460 R15: 1ffff110170c5082 FS: 0000000000000000(0000) GS:ffff888124f5a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffec48ff798 CR3: 000000000e946000 CR4: 0000000000350ef0 Call Trace: cpu_max_bits_warn include/linux/cpumask.h:140 [inline] cpumask_check include/linux/cpumask.h:147 [inline] cpumask_test_cpu include/linux/cpumask.h:651 [inline] cpu_online include/linux/cpumask.h:1233 [inline] trace_hrtimer_expire_exit include/trace/events/timer.h:321 [inline] __run_hrtimer kernel/time/hrtimer.c:2035 [inline] __hrtimer_run_queues+0x404/0xa10 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x448/0x910 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872 Code: ff ff ff e8 c1 3f 2c 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 ab 3a ca 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 7b 1b 6e ff cc 48 8d 3d f8 d5 b8 RSP: 0018:ffffc90005d67540 EFLAGS: 00000282 RAX: 14ae2db391c41800 RBX: 0000000000000000 RCX: 0000000000000046 RDX: 00000000a69b4a9e RSI: ffffffff8e4aed03 RDI: ffffffff8c4bd280 RBP: ffffffff8176f21f R08: ffffffff8176f21f R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8eb59c60 R12: 0000000000000002 R13: ffffffff8eb59c60 R14: 0000000000000000 R15: 0000000000000246 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:840 [inline] class_rcu_constructor include/linux/rcupdate.h:1183 [inline] unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556 slab_free_hook mm/slub.c:2666 [inline] slab_free mm/slub.c:6405 [inline] kmem_cache_free+0x44f/0x650 mm/slub.c:6532 tear_down_vmas+0x312/0x520 mm/mmap.c:1262 exit_mmap+0x4ca/0x9f0 mm/mmap.c:1320 __mmput+0x118/0x420 kernel/fork.c:1187 exit_mm+0x221/0x2d0 kernel/exit.c:610 do_exit+0x6cd/0x2360 kernel/exit.c:992 do_group_exit+0x22d/0x2f0 kernel/exit.c:1147 __do_sys_exit_group kernel/exit.c:1158 [inline] __se_sys_exit_group kernel/exit.c:1156 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1156 x64_sys_call+0x221a/0x2240 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa0091976c5 Code: Unable to access opcode bytes at 0x7fa00919769b. RSP: 002b:00007ffec48ffe38 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007ffec4900104 RCX: 00007fa0091976c5 RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000000 RBP: 0000000000000003 R08: 00007ffec48fff30 R09: 0000000000000002 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007ffec4900170 R14: 00007fa0093a7000 R15: 000055b0bcb26d98 rcu: rcu_preempt kthread starved for 10505 jiffies! g119061 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:27752 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7326 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325 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: CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64 Code: 1c 81 02 e9 fe df 41 f5 cc cc cc 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 0a 1b 00 fb f4 d7 df 41 f5 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 RSP: 0018:ffffc90000197e40 EFLAGS: 00000242 RAX: 0000000003f3bd83 RBX: ffffffff819ab2dc RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8e229adb RDI: ffffffff8c4bd280 RBP: ffffc90000197f10 R08: ffff8880b87338db R09: 1ffff110170e671b R10: dffffc0000000000 R11: ffffed10170e671c R12: 0000000000000000 R13: 1ffff11003bd5000 R14: 1ffff92000032fd0 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff88812505a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa009367368 CR3: 00000000336c4000 CR4: 0000000000350ef0 Call Trace: arch_safe_halt arch/x86/kernel/process.c:767 [inline] default_idle+0x9/0x20 arch/x86/kernel/process.c:768 default_idle_call+0x72/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:199 [inline] do_idle+0x1cc/0x540 kernel/sched/idle.c:355 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:454 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x157