rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=76d/1/0x4000000000000000 softirq=43217/43221 fqs=265 (detected by 1, t=10505 jiffies, g=50265, q=24721) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 21108 Comm: syz.2.7400 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 RIP: 0010:rcu_read_lock include/linux/rcupdate.h:740 [inline] RIP: 0010:__perf_output_begin kernel/events/ring_buffer.c:163 [inline] RIP: 0010:perf_output_begin_forward+0x97/0xa30 kernel/events/ring_buffer.c:271 Code: 49 c1 ec 03 48 b8 f1 f1 f1 f1 00 00 00 f3 49 89 04 0c 41 c7 44 0c 08 f3 f3 f3 f3 e8 23 c1 dd ff e8 4e 51 ca ff e8 89 56 00 00 04 2b 0f 08 41 89 c6 31 ff 89 c6 e8 68 c4 dd ff 45 85 f6 74 15 RSP: 0000:ffffc90004e97340 EFLAGS: 00000082 RAX: ef2aee64be444300 RBX: ffff88805c39cd98 RCX: ef2aee64be444300 RDX: 0000000000000000 RSI: ffffffff8a0b2ac0 RDI: ffffffff8a59a4c0 RBP: ffffc90004e97470 R08: dffffc0000000000 R09: fffffbfff1ff7a19 R10: fffffbfff1ff7a19 R11: 1ffffffff1ff7a18 R12: 1ffff920009d2e78 R13: 0000000000000018 R14: ffffc90004e974c0 R15: ffffc90004e97680 FS: 000055555d853500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2eb63fff CR3: 0000000077d46000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __perf_event_output kernel/events/core.c:7804 [inline] perf_event_output_forward+0x15c/0x280 kernel/events/core.c:7822 __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515 perf_tp_event+0x32c/0xb50 kernel/events/core.c:10047 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021 perf_trace_preemptirq_template+0x2be/0x380 include/trace/events/preemptirq.h:14 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713 RIP: 0010:rcu_read_unlock_special+0x84/0x480 kernel/rcu/tree_plugin.h:674 Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 ad 13 9e 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b RSP: 0000:ffffc90004e97ac0 EFLAGS: 00000206 RAX: ef2aee64be444300 RBX: 1ffff920009d2f5c RCX: ef2aee64be444300 RDX: dffffc0000000000 RSI: ffffffff8a0b1820 RDI: ffffffff8a59a4c0 RBP: ffffc90004e97b98 R08: dffffc0000000000 R09: fffffbfff1ff7a19 R10: fffffbfff1ff7a19 R11: 1ffffffff1ff7a18 R12: ffffffff8c120b00 R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422 rcu_read_unlock include/linux/rcupdate.h:771 [inline] __unlock_page_memcg+0xea/0x100 mm/memcontrol.c:2093 do_set_pte+0x3c9/0x530 mm/memory.c:4069 finish_fault+0x52e/0x8d0 mm/memory.c:4143 do_shared_fault mm/memory.c:4336 [inline] do_fault mm/memory.c:4396 [inline] handle_pte_fault mm/memory.c:4650 [inline] __handle_mm_fault mm/memory.c:4785 [inline] handle_mm_fault+0x2157/0x43c0 mm/memory.c:4883 do_user_addr_fault+0x489/0xc80 arch/x86/mm/fault.c:1357 handle_page_fault arch/x86/mm/fault.c:1445 [inline] exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1501 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606 RIP: 0033:0x7f3f59b841f1 Code: 65 5a ff ff 48 8b 05 86 45 eb 00 0f b6 4c 24 10 be 08 00 00 00 48 89 df 83 05 62 45 eb 00 01 48 8d 50 ff 48 89 15 67 45 eb 00 <88> 48 ff 8b 2d 4e 45 eb 00 e8 31 5a ff ff 48 8b 05 5a 45 eb 00 41 RSP: 002b:00007fff9c228660 EFLAGS: 00010202 RAX: 0000001b2eb64000 RBX: 00007f3f5aa38720 RCX: 0000000000000003 RDX: 0000001b2eb63fff RSI: 0000000000000008 RDI: 00007f3f5aa38720 RBP: 00007f3f59f09038 R08: 0000000000000000 R09: 0000000000000000 R10: 00007f3f5aa38700 R11: 0000000000000001 R12: 0000000000000003 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 9180 jiffies! g50265 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:27744 pid: 15 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11bb/0x4390 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 1 CPU: 1 PID: 9 Comm: kworker/u4:0 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Workqueue: writeback wb_workfn (flush-8:0) Call Trace: dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline] rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487 print_other_cpu_stall+0x10c8/0x1220 kernel/rcu/tree_stall.h:592 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline] rcu_pending kernel/rcu/tree.c:3936 [inline] rcu_sched_clock_irq+0x831/0x1110 kernel/rcu/tree.c:2619 update_process_times+0x193/0x200 kernel/time/timer.c:1818 tick_sched_handle kernel/time/tick-sched.c:254 [inline] tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline] __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline] RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline] RIP: 0010:kvm_wait+0x141/0x190 arch/x86/kernel/kvm.c:918 Code: 89 df 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 47 0f b6 1f e8 5f e0 49 00 44 38 e3 75 10 66 90 0f 00 2d e1 65 d4 08 fb f4 33 ff ff ff fb e9 2d ff ff ff e8 8f 26 75 08 89 f9 80 e1 07 38 RSP: 0018:ffffc90000ce65c0 EFLAGS: 00000246 RAX: 283126bf5f616400 RBX: 0000000000000003 RCX: 283126bf5f616400 RDX: dffffc0000000000 RSI: ffffffff8a0b1820 RDI: ffffffff8a59a4c0 RBP: ffffc90000ce6670 R08: dffffc0000000000 R09: fffffbfff1ff7a19 R10: fffffbfff1ff7a19 R11: 1ffffffff1ff7a18 R12: 0000000000000003 R13: ffff8880b913b154 R14: dffffc0000000000 R15: 1ffff9200019ccb8 pv_wait arch/x86/include/asm/paravirt.h:597 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline] __pv_queued_spin_lock_slowpath+0x60f/0x9c0 kernel/locking/qspinlock.c:508 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline] queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51 queued_spin_lock include/asm-generic/qspinlock.h:85 [inline] do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115 page_vma_mapped_walk+0x1468/0x1740 mm/page_vma_mapped.c:-1 page_mkclean_one+0x148/0x380 mm/rmap.c:926 rmap_walk_file+0x408/0x610 mm/rmap.c:2378 rmap_walk mm/rmap.c:2396 [inline] page_mkclean+0x2da/0x3e0 mm/rmap.c:1006 clear_page_dirty_for_io+0x402/0x9e0 mm/page-writeback.c:2749 mpage_submit_page+0x8a/0x210 fs/ext4/inode.c:2093 mpage_process_page_bufs+0x6d8/0x8b0 fs/ext4/inode.c:2227 mpage_prepare_extent_to_map+0xb7d/0xf70 fs/ext4/inode.c:2655 ext4_writepages+0xa09/0x2d20 fs/ext4/inode.c:2783 do_writepages+0x48d/0x6d0 mm/page-writeback.c:2386 __writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1647 writeback_sb_inodes+0x9fe/0x1610 fs/fs-writeback.c:1930 __writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2001 wb_writeback+0x455/0xb90 fs/fs-writeback.c:2106 wb_check_old_data_flush fs/fs-writeback.c:2206 [inline] wb_do_writeback fs/fs-writeback.c:2259 [inline] wb_workfn+0xaaa/0xe60 fs/fs-writeback.c:2288 process_one_work+0x863/0x1000 kernel/workqueue.c:2310 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287