rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=ee9c/0/0x1 softirq=16477/16478 fqs=150 rcu: (detected by 0, t=10502 jiffies, g=9117, q=370 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 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 07/12/2025 RIP: 0010:__kasan_check_read+0xa/0x20 mm/kasan/shadow.c:31 Code: 31 ed eb cf cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 89 f6 48 8b 0c 24 <31> d2 e9 ef e4 ff ff 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 RSP: 0018:ffffc90000a08c40 EFLAGS: 00000046 RAX: 0000000000000000 RBX: ffffffff99d980e0 RCX: ffffffff819e033d RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff99d980e0 RBP: ffffc90000a08d08 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000141170 R12: dffffc0000000000 R13: dffffc0000000000 R14: ffffffff99d980e4 R15: 1ffff92000141190 FS: 0000000000000000(0000) GS:ffff888125d1b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fb55d269f98 CR3: 000000000df36000 CR4: 0000000000350ef0 Call Trace: instrument_atomic_read include/linux/instrumented.h:68 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] queued_spin_is_locked include/asm-generic/qspinlock.h:57 [inline] debug_spin_unlock kernel/locking/spinlock_debug.c:101 [inline] do_raw_spin_unlock+0x4d/0x240 kernel/locking/spinlock_debug.c:141 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:150 [inline] _raw_spin_unlock_irqrestore+0x78/0x110 kernel/locking/spinlock.c:194 debug_hrtimer_deactivate kernel/time/hrtimer.c:450 [inline] debug_deactivate+0x1d/0x200 kernel/time/hrtimer.c:490 __run_hrtimer kernel/time/hrtimer.c:1729 [inline] __hrtimer_run_queues+0x2b0/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 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+0x13/0x20 arch/x86/kernel/paravirt.c:82 Code: 3e cd 96 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 f3 b6 0e 00 f3 0f 1e fa fb f4 13 cd 96 f5 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90000197de0 EFLAGS: 000002c2 RAX: 7b150d282ec6a900 RBX: ffffffff819683b8 RCX: 7b150d282ec6a900 RDX: 0000000000000001 RSI: ffffffff8be33660 RDI: ffffffff819683b8 RBP: ffffc90000197f20 R08: ffff8880b8732f9b R09: 1ffff110170e65f3 R10: dffffc0000000000 R11: ffffed10170e65f4 R12: ffffffff8fa38330 R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff11003954b40 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:757 default_idle_call+0x74/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:190 [inline] do_idle+0x1e8/0x510 kernel/sched/idle.c:330 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:428 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:315 common_startup_64+0x13e/0x147 rcu: rcu_preempt kthread starved for 10202 jiffies! g9117 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:27496 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0x165/0x360 kernel/sched/core.c:7058 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+0x3fc/0x770 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: 0 UID: 0 PID: 5863 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:get_current arch/x86/include/asm/current.h:25 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70 kernel/kcov.c:216 Code: 8b 3d c4 49 fe 0b 48 89 de 5b e9 73 98 58 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0c 25 08 50 a0 92 65 8b 15 e8 a4 e0 10 81 e2 00 01 ff 00 RSP: 0000:ffffc90002e57718 EFLAGS: 00000202 RAX: ffffffff81b44ceb RBX: 1ffff110170e7f61 RCX: ffff888078ac3c00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90002e578a0 R08: ffffffff8fa38337 R09: 1ffffffff1f47066 R10: dffffc0000000000 R11: fffffbfff1f47067 R12: ffff8880b873fb08 R13: dffffc0000000000 R14: ffff8880b863b1c0 R15: 0000000000000001 FS: 00007fcc4f3e6880(0000) GS:ffff888125c1b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000056208b7637c0 CR3: 0000000026a39000 CR4: 0000000000350ef0 Call Trace: csd_lock_wait kernel/smp.c:342 [inline] smp_call_function_many_cond+0xd4b/0x12d0 kernel/smp.c:877 on_each_cpu_cond_mask+0x3f/0x80 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+0x6b1/0x12d0 arch/x86/mm/tlb.c:1451 flush_tlb_page arch/x86/include/asm/tlbflush.h:324 [inline] ptep_clear_flush+0x120/0x170 mm/pgtable-generic.c:101 wp_page_copy mm/memory.c:3618 [inline] do_wp_page+0x1bc2/0x5800 mm/memory.c:4013 handle_pte_fault mm/memory.c:6068 [inline] __handle_mm_fault+0x1033/0x5440 mm/memory.c:6195 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 RIP: 0033:0x7fcc4ecb5dda Code: f6 44 01 08 01 74 59 48 83 61 08 fe 48 3d ff 03 00 00 76 69 49 8b 55 70 49 8d 75 60 48 39 72 18 0f 85 ba 00 00 00 66 0f ef c0 <41> 0f 11 44 24 20 49 89 54 24 10 49 89 74 24 18 4c 89 66 10 4c 89 RSP: 002b:00007ffcf3655c10 EFLAGS: 00010246 RAX: 0000000000003000 RBX: 00000000000008a0 RCX: 000056208b765f00 RDX: 000056208b7375b0 RSI: 00007fcc4edf1b20 RDI: 000056208b765f00 RBP: 00007fcc4edf1ac0 R08: 00000000000008a0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 000056208b7637a0 R13: 00007fcc4edf1ac0 R14: 00000000000008a0 R15: 00007fcc4edf1ac0