rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (2 ticks this GP) idle=27f4/1/0x4000000000000000 softirq=15997/15997 fqs=0 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5186/2:b..l rcu: (detected by 1, t=10514 jiffies, g=9877, q=921 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 5960 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:arch_atomic_try_cmpxchg arch/x86/include/asm/atomic.h:107 [inline] RIP: 0010:raw_atomic_try_cmpxchg_acquire include/linux/atomic/atomic-arch-fallback.h:2170 [inline] RIP: 0010:atomic_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1302 [inline] RIP: 0010:queued_spin_lock include/asm-generic/qspinlock.h:111 [inline] RIP: 0010:do_raw_spin_lock+0x130/0x2b0 kernel/locking/spinlock_debug.c:116 Code: 00 00 48 89 df be 04 00 00 00 c7 44 24 28 00 00 00 00 e8 13 8b 8e 00 be 04 00 00 00 48 8d 7c 24 28 e8 04 8b 8e 00 8b 44 24 28 01 00 00 00 89 44 24 04 f0 0f b1 13 0f 85 94 00 00 00 65 44 8b RSP: 0000:ffffc90000007da8 EFLAGS: 00000097 RAX: 0000000000000000 RBX: ffff8880b8428440 RCX: ffffffff819a555c RDX: fffff52000000fba RSI: 0000000000000004 RDI: ffffc90000007dd0 RBP: 1ffff92000000fb6 R08: 0000000000000001 R09: fffff52000000fba R10: 0000000000000003 R11: ffff88802d010b30 R12: ffff8880b8428448 R13: ffff8880b8428450 R14: ffff88807907c300 R15: 0000000000000001 FS: 00007f858717f880(0000) GS:ffff8881248f1000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000558b11eb8fe8 CR3: 00000000763b6000 CR4: 00000000003526f0 Call Trace: __run_hrtimer kernel/time/hrtimer.c:1781 [inline] __hrtimer_run_queues+0x2bc/0xc40 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x10b/0x3c0 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xdfd/0x15e0 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 45 5f 0c 00 f3 90 <41> 0f b6 45 00 40 38 c5 7c 08 84 c0 0f 85 b6 05 00 00 8b 43 08 31 RSP: 0000:ffffc90003fcf8a8 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b8540cc0 RCX: ffffffff81b29d31 RDX: ffff88802d010000 RSI: ffffffff81b29d0b RDI: 0000000000000005 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: ffff88802d010b30 R12: dffffc0000000000 R13: ffffed10170a8199 R14: 0000000000000001 R15: 0000000000000001 on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1043 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1382 [inline] flush_tlb_mm_range+0x2f0/0x12c0 arch/x86/mm/tlb.c:1472 flush_tlb_page arch/x86/include/asm/tlbflush.h:324 [inline] ptep_clear_flush+0x136/0x180 mm/pgtable-generic.c:103 wp_page_copy mm/memory.c:3785 [inline] do_wp_page+0x171f/0x5010 mm/memory.c:4180 handle_pte_fault mm/memory.c:6289 [inline] __handle_mm_fault+0x1bd2/0x2bb0 mm/memory.c:6411 handle_mm_fault+0x3fe/0xad0 mm/memory.c:6580 do_user_addr_fault+0x60c/0x1370 arch/x86/mm/fault.c:1336 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x64/0xc0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 RIP: 0033:0x7f8586ab5db7 Code: 00 00 00 41 55 48 89 d0 49 89 fd 41 54 49 89 f4 53 4c 89 c3 48 83 ec 10 48 39 4f 60 0f 84 c1 00 00 00 42 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 RSP: 002b:00007ffdc96b93c0 EFLAGS: 00010202 RAX: 0000000000006010 RBX: 00000000000001f0 RCX: 0000558b11eb8fe0 RDX: 0000000000006010 RSI: 0000558b11eb2fd0 RDI: 00007f8586bf1ac0 RBP: 00007f8586bf1ac0 R08: 00000000000001f0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000558b11eb2fd0 R13: 00007f8586bf1ac0 R14: 00000000000001f0 R15: 00007f8586bf1ac0 task:udevd state:R running task stack:26552 pid:5186 tgid:5186 ppid:1 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:7047 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock_irqrestore+0x61/0x80 kernel/locking/spinlock.c:194 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline] unlock_task_sighand include/linux/sched/signal.h:756 [inline] do_send_sig_info kernel/signal.c:1270 [inline] group_send_sig_info+0x2d5/0x300 kernel/signal.c:1419 kill_pid_info_type+0x92/0x2a0 kernel/signal.c:1459 kill_pid_info kernel/signal.c:1473 [inline] kill_proc_info+0x6f/0x1b0 kernel/signal.c:1480 kill_something_info+0x2a2/0x310 kernel/signal.c:1577 __do_sys_kill kernel/signal.c:3953 [inline] __se_sys_kill kernel/signal.c:3947 [inline] __x64_sys_kill+0xd7/0x140 kernel/signal.c:3947 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f8586a5f357 RSP: 002b:00007ffdc96b9618 EFLAGS: 00000297 ORIG_RAX: 000000000000003e RAX: ffffffffffffffda RBX: 00007ffdc96b9620 RCX: 00007f8586a5f357 RDX: 0000558b11c87080 RSI: 000000000000000f RDI: 0000000000001748 RBP: 0000000000000000 R08: 0000000000000010 R09: 0000558b11eba020 R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000000 R13: 0000558aed515100 R14: 0000000000000000 R15: 0000000000000000 rcu: rcu_preempt kthread timer wakeup didn't happen for 10513 jiffies! g9877 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=6747 rcu: rcu_preempt kthread starved for 10514 jiffies! g9877 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:28440 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6960 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246