rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (0 ticks this GP) idle=7ac4/1/0x4000000000000000 softirq=54497/54497 fqs=1 rcu: (detected by 0, t=10502 jiffies, g=62977, q=230 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 12310 Comm: syz.1.1742 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/10/2026 RIP: 0010:__this_cpu_preempt_check+0x0/0x20 lib/smp_processor_id.c:63 Code: c6 00 0f 40 8c 48 c7 c7 40 0f 40 8c e9 f9 fe ff ff 66 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 80 0f 40 8c e9 cd fe ff ff 66 2e 0f RSP: 0018:ffffc90000a08d58 EFLAGS: 00000096 RAX: 0000000000000001 RBX: 0000000000000000 RCX: ac156fbfe921c2fb RDX: 0000000000000000 RSI: 00000000109fc3dd RDI: ffffffff8e17df68 RBP: ffff8880486d62c0 R08: 00000000ffffffff R09: 0000000000000d83 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f5c00d996c0(0000) GS:ffff888123ee8000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f54a419c440 CR3: 000000007409e000 CR4: 00000000003526f0 Call Trace: lockdep_recursion_finish kernel/locking/lockdep.c:470 [inline] lock_acquire kernel/locking/lockdep.c:5870 [inline] lock_acquire+0x1c9/0x370 kernel/locking/lockdep.c:5825 __raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158 spin_lock include/linux/spinlock.h:342 [inline] advance_sched+0xe5/0xd20 net/sched/sch_taprio.c:930 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x462/0x9c0 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x3e5/0x940 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x109/0x470 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:198 Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 56 30 29 f6 48 89 df e8 de 7f 29 f6 f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 01 00 00 00 e8 a5 8f 18 f6 65 8b 05 ee 38 a7 08 85 c0 74 16 5b RSP: 0018:ffffc90004a4fd78 EFLAGS: 00000246 RAX: 0000000000000006 RBX: ffffffff9b7333d8 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8e1a3c59 RDI: ffffffff8c400f80 RBP: 0000000000000283 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: ffffffffffffffff R12: 1ffff92000949fb6 R13: 000000000cdfb43b R14: 000000000cdfb43b R15: 0000000000000000 class_raw_spinlock_irqsave_destructor include/linux/spinlock.h:571 [inline] do_settimeofday64+0x326/0x4d0 kernel/time/timekeeping.c:1665 do_sys_settimeofday64+0x1dc/0x260 kernel/time/time.c:195 __do_sys_clock_settime kernel/time/posix-timers.c:1139 [inline] __se_sys_clock_settime kernel/time/posix-timers.c:1123 [inline] __x64_sys_clock_settime+0x1c1/0x2a0 kernel/time/posix-timers.c:1123 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5bfff9de59 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5c00d99028 EFLAGS: 00000246 ORIG_RAX: 00000000000000e3 RAX: ffffffffffffffda RBX: 00007f5c00225fa0 RCX: 00007f5bfff9de59 RDX: 0000000000000000 RSI: 0000200000000040 RDI: 0000000000000000 RBP: 00007f5c00033e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5c00226038 R14: 00007f5c00225fa0 R15: 00007ffd12843cf8 rcu: rcu_preempt kthread starved for 10500 jiffies! g62977 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:27672 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7326 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2325 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 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: 12335 Comm: modprobe Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/10/2026 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0x589/0x16c0 kernel/smp.c:892 Code: b8 00 00 00 00 00 fc ff df 48 8b 54 24 08 49 89 d5 49 89 d4 49 c1 ed 03 41 83 e4 07 49 01 c5 41 83 c4 03 e8 c9 95 0c 00 f3 90 <41> 0f b6 45 00 41 38 c4 7c 08 84 c0 0f 85 2c 0f 00 00 8b 45 08 31 RSP: 0018:ffffc9000245f8a8 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81fd46fd RDX: ffff88801f3a0000 RSI: ffffffff81fd46d7 RDI: ffff88801f3a0000 RBP: ffff8880b8541240 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003 R13: ffffed10170a8249 R14: 0000000000000001 R15: ffff8880b843c880 FS: 0000000000000000(0000) GS:ffff888123de8000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f54a4122e9c CR3: 000000000e992000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1057 __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x45f/0x16f0 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:509 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:499 [inline] tlb_flush_mmu mm/mmu_gather.c:423 [inline] tlb_finish_mmu+0x3fe/0x810 mm/mmu_gather.c:549 exit_mmap+0x454/0xa00 mm/mmap.c:1313 __mmput+0x12a/0x410 kernel/fork.c:1187 mmput+0x67/0x80 kernel/fork.c:1210 exit_mm kernel/exit.c:615 [inline] do_exit+0x8b1/0x2ae0 kernel/exit.c:997 do_group_exit+0xd5/0x2a0 kernel/exit.c:1152 __do_sys_exit_group kernel/exit.c:1163 [inline] __se_sys_exit_group kernel/exit.c:1161 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1161 x64_sys_call+0x102c/0x1530 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f54a42816c5 Code: Unable to access opcode bytes at 0x7f54a428169b. RSP: 002b:00007ffdfa2af978 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007f54a4382fe8 RCX: 00007f54a42816c5 RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000001 RBP: 0000000000000001 R08: 00007ffdfa2af908 R09: 0000000000000000 R10: 00007ffdfa2af7a0 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000001 R14: 00007f54a4381680 R15: 00007f54a4383000