rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (1 GPs behind) idle=d29/1/0x4000000000000000 softirq=49506/49509 fqs=16 (t=10502 jiffies g=59217 q=1163) rcu: rcu_preempt kthread starved for 10436 jiffies! g59217 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:27800 pid: 15 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117 rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972 rcu_gp_kthread+0x9b/0x370 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: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 12931 Comm: syz.3.2131 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:cpu_max_bits_warn include/linux/cpumask.h:108 [inline] RIP: 0010:cpumask_check include/linux/cpumask.h:115 [inline] RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:344 [inline] RIP: 0010:cpu_online include/linux/cpumask.h:895 [inline] RIP: 0010:trace_user_enter+0x2a/0x190 include/trace/events/context_tracking.h:34 Code: 41 56 53 e8 28 b7 db ff 0f 1f 44 00 00 e8 1e b7 db ff 65 8b 1d df 97 64 7e bf 07 00 00 00 89 de e8 6b ba db ff 83 fb 07 77 55 01 b7 db ff 41 89 de c1 eb 06 48 8d 3c dd 28 f0 89 8d be 08 00 RSP: 0018:ffffc9000411fee0 EFLAGS: 00000097 RAX: ffffffff819d7d85 RBX: 0000000000000000 RCX: ffff888018395940 RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000007 RBP: ffffc9000411ff48 R08: ffffffff8d89f02f R09: 1ffffffff1b13e05 R10: dffffc0000000000 R11: fffffbfff1b13e06 R12: 0000000000000000 R13: 0000000000000000 R14: ffff888018395940 R15: 0000000000000027 FS: 00007f47f1f626c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000006b000 CR3: 000000005fc95000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __context_tracking_enter+0x58/0x90 kernel/context_tracking.c:81 user_enter_irqoff include/linux/context_tracking.h:41 [inline] __exit_to_user_mode kernel/entry/common.c:136 [inline] syscall_exit_to_user_mode+0x3c/0x40 kernel/entry/common.c:309 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f47f3d02b57 Code: 8d 3d b8 8a 0b 00 e8 58 1d fa ff e8 a3 87 00 00 0f 1f 00 b8 68 00 00 00 0f 05 c3 0f 1f 84 00 00 00 00 00 b8 27 00 00 00 0f 05 0f 1f 84 00 00 00 00 00 b8 6e 00 00 00 0f 05 c3 0f 1f 84 00 00 RSP: 002b:00007f47f1f61a48 EFLAGS: 00000206 ORIG_RAX: 0000000000000027 RAX: 0000000000000563 RBX: 00007f47f1f61bb0 RCX: 00007f47f3d02b57 RDX: 00007f47f1f61a80 RSI: 00007f47f1f61bb0 RDI: 0000000000000021 RBP: 0000000000000000 R08: 0000000000000007 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 00007f47f3f82038 R14: 00007f47f3f81fa0 R15: 00007ffeb86a59c8 NMI backtrace for cpu 1 CPU: 1 PID: 12928 Comm: syz.4.2130 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 nmi_cpu_backtrace+0x3a2/0x3d0 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_dump_cpu_stacks+0x22f/0x380 kernel/rcu/tree_stall.h:349 print_cpu_stall+0x31d/0x5f0 kernel/rcu/tree_stall.h:633 check_cpu_stall kernel/rcu/tree_stall.h:727 [inline] rcu_pending kernel/rcu/tree.c:3936 [inline] rcu_sched_clock_irq+0x6ea/0x1120 kernel/rcu/tree.c:2619 update_process_times+0x193/0x200 kernel/time/timer.c:2021 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+0x4b4/0xb70 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:__syscall_enter_from_user_work kernel/entry/common.c:93 [inline] RIP: 0010:syscall_enter_from_user_mode+0x2a/0x70 kernel/entry/common.c:114 Code: 41 56 53 48 89 f3 49 89 fe 48 8b 7c 24 10 e8 3d f6 ff ff eb 31 eb 35 e8 74 8d c2 f7 e8 6f 8b c2 f7 fb 65 48 8b 05 d6 9a 45 76 <48> 8b 70 08 40 f6 c6 3f 74 0b 4c 89 f7 5b 41 5e e9 11 8b aa f7 48 RSP: 0018:ffffc90004817f08 EFLAGS: 00000286 RAX: ffff888022c49dc0 RBX: 0000000000000027 RCX: 05a1cc9f0004aa00 RDX: dffffc0000000000 RSI: ffffffff8a2b2800 RDI: ffffffff8a79fe00 RBP: ffffc90004817f48 R08: ffffffff8d89f02f R09: 1ffffffff1b13e05 R10: dffffc0000000000 R11: fffffbfff1b13e06 R12: 0000000000000000 R13: 0000000000000000 R14: ffffc90004817f58 R15: 0000000000000000 do_syscall_64+0x24/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f8694c04b57 Code: 8d 3d b8 8a 0b 00 e8 58 1d fa ff e8 a3 87 00 00 0f 1f 00 b8 68 00 00 00 0f 05 c3 0f 1f 84 00 00 00 00 00 b8 27 00 00 00 0f 05 0f 1f 84 00 00 00 00 00 b8 6e 00 00 00 0f 05 c3 0f 1f 84 00 00 RSP: 002b:00007f8692e63b08 EFLAGS: 00000202 ORIG_RAX: 0000000000000027 RAX: ffffffffffffffda RBX: 00007f8692e63c70 RCX: 00007f8694c04b57 RDX: 00007f8692e63b40 RSI: 00007f8692e63c70 RDI: 0000000000000021 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007f8694e84038 R14: 00007fffb56f41f0 R15: 00007fffb56f42d8