rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (2 GPs behind) idle=86c4/0/0x1 softirq=27162/27163 fqs=0 rcu: (detected by 1, t=10504 jiffies, g=15657, q=865 ncpus=2) 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:timerqueue_add+0x1cd/0x330 lib/timerqueue.c:41 Code: 45 84 f6 0f 85 a9 00 00 00 e8 cf 13 2b f6 48 8b 34 24 48 89 ef e8 c3 86 ff ff e8 be 13 2b f6 44 89 f0 48 83 c4 08 5b 5d 41 5c <41> 5d 41 5e 41 5f c3 cc cc cc cc e8 a3 13 2b f6 48 89 ea 48 b8 00 RSP: 0018:ffffc90000007e20 EFLAGS: 00000082 RAX: 00000000522d8301 RBX: ffff8880b8427d80 RCX: ffffffff8b907998 RDX: ffffffff8e2977c0 RSI: ffffffff8b907b12 RDI: ffff8880522d8340 RBP: 0000000000000001 R08: 0000000000000006 R09: ffff8880522d8340 R10: ffff8880522d8340 R11: ffffffff9b0622d8 R12: ffff8880b8427c80 R13: 0000000000000000 R14: ffff8880522d8301 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8881246b5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055cc1b6d1300 CR3: 00000000749c1000 CR4: 00000000003526f0 Call Trace: __run_hrtimer kernel/time/hrtimer.c:1778 [inline] __hrtimer_run_queues+0x8ff/0xad0 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x10b/0x3f0 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0x9f/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: cc 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 b3 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: 00000000000c85bb RBX: 0000000000000000 RCX: ffffffff8b945c29 RDX: 0000000000000000 RSI: ffffffff8de522e8 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 rcu: rcu_preempt kthread starved for 10504 jiffies! g15657 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: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: CPU: 1 UID: 0 PID: 6693 Comm: dhcpcd-run-hook Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xdfd/0x1600 kernel/smp.c:877 Code: 57 48 8b 54 24 10 4c 89 74 24 10 49 89 d5 48 89 d5 48 89 54 24 18 49 c1 ed 03 83 e5 07 4d 01 e5 83 c5 03 e8 d5 ff 0b 00 f3 90 <41> 0f b6 45 00 40 38 c5 7c 08 84 c0 0f 85 e0 05 00 00 8b 43 08 31 RSP: 0018:ffffc90003717930 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b8442000 RCX: ffffffff81af8f21 RDX: ffff888032e34880 RSI: ffffffff81af8efb RDI: 0000000000000005 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: dffffc0000000000 R13: ffffed1017088401 R14: 0000000000000001 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881247b5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9fa5839368 CR3: 00000000316b4000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x40/0x90 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+0x4a0/0x17a0 arch/x86/mm/tlb.c:1451 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:490 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:480 [inline] tlb_flush_mmu mm/mmu_gather.c:403 [inline] tlb_finish_mmu+0x3c9/0x7c0 mm/mmu_gather.c:497 exit_mmap+0x403/0xb90 mm/mmap.c:1293 __mmput+0x12a/0x410 kernel/fork.c:1129 mmput+0x62/0x70 kernel/fork.c:1152 exit_mm kernel/exit.c:582 [inline] do_exit+0x7c7/0x2bf0 kernel/exit.c:949 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102 __do_sys_exit_group kernel/exit.c:1113 [inline] __se_sys_exit_group kernel/exit.c:1111 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1111 x64_sys_call+0x14fa/0x1720 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9fa56696c5 Code: Unable to access opcode bytes at 0x7f9fa566969b. RSP: 002b:00007ffc816c4268 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007ffc816c4504 RCX: 00007f9fa56696c5 RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000000 RBP: 0000000000000003 R08: 00007ffc816c4360 R09: 0000000000000002 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007ffc816c45a0 R14: 00007f9fa5879000 R15: 000055cbf8b36d98