rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 0, t=10502 jiffies, g=7097, q=12 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10500 (4294969452-4294958952), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10500 jiffies! g7097 f0x2 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:26256 pid:16 tgid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5409 [inline] __schedule+0x17e8/0x4a50 kernel/sched/core.c:6746 __schedule_loop kernel/sched/core.c:6823 [inline] schedule+0x14b/0x320 kernel/sched/core.c:6838 schedule_timeout+0x1be/0x310 kernel/time/timer.c:2582 rcu_gp_fqs_loop+0x2df/0x1370 kernel/rcu/tree.c:1663 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:1862 kthread+0x2f2/0x390 kernel/kthread.c:388 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 5127 Comm: syz-executor844 Not tainted 6.9.0-rc5-syzkaller-00031-g71b1543c83d6 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 RIP: 0010:rcu_is_watching+0x0/0xb0 kernel/rcu/tree.c:696 Code: 4c 89 f6 e8 82 71 6c 03 e9 2b ff ff ff e8 68 6b 03 0a 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 41 57 41 56 53 65 ff 05 08 82 87 7e e8 9b 89 03 0a 89 RSP: 0018:ffffc90000a08bc0 EFLAGS: 00000046 RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffff88807e7bbc00 RDX: ffff88807e7bbc00 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90000a08c80 R08: ffffffff815c5b50 R09: 1ffffffff25e64a0 R10: dffffc0000000000 R11: fffffbfff25e64a1 R12: ffff888028658940 R13: 1ffff1100fcf78a2 R14: ffff88807e7bc510 R15: 1ffff92000141190 FS: 0000555584b6f3c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000002006b000 CR3: 000000002281c000 CR4: 0000000000350ef0 Call Trace: rcu_read_lock_held_common kernel/rcu/update.c:109 [inline] rcu_read_lock_held+0x15/0x50 kernel/rcu/update.c:349 __lock_task_sighand+0x119/0x2e0 kernel/signal.c:1399 lock_task_sighand include/linux/sched/signal.h:746 [inline] send_sigqueue+0x25d/0x760 kernel/signal.c:1997 posix_timer_event kernel/time/posix-timers.c:298 [inline] posix_timer_fn+0x18a/0x3a0 kernel/time/posix-timers.c:324 __run_hrtimer kernel/time/hrtimer.c:1692 [inline] __hrtimer_run_queues+0x5a7/0xd50 kernel/time/hrtimer.c:1756 hrtimer_interrupt+0x396/0x990 kernel/time/hrtimer.c:1818 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1032 [inline] __sysvec_apic_timer_interrupt+0x112/0x3f0 arch/x86/kernel/apic/apic.c:1049 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1043 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202 Code: 90 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 1a 18 e8 f5 48 89 df e8 32 58 e9 f5 e8 fd b4 12 f6 fb bf 01 00 00 00 f2 1d db f5 65 8b 05 63 4a 79 74 85 c0 74 06 5b e9 9c b7 25 00 RSP: 0018:ffffc900047ffc70 EFLAGS: 00000282 RAX: 63e827c788281200 RBX: ffff888028658940 RCX: ffffffff9472a603 RDX: dffffc0000000000 RSI: ffffffff8bcab8a0 RDI: 0000000000000001 RBP: ffffc900047ffdb0 R08: ffffffff8fa8e32f R09: 1ffffffff1f51c65 R10: dffffc0000000000 R11: fffffbfff1f51c66 R12: 0000000000000021 R13: 1ffff110050cb1bb R14: ffff888028658dd8 R15: ffff888028658940 spin_unlock_irq include/linux/spinlock.h:401 [inline] get_signal+0x14dd/0x1740 kernel/signal.c:2914 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218 do_syscall_64+0x102/0x240 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f84553a3e79 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 18 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fffe1fd3438 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007f84553a3e79 RDX: 000000002006b000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00000000000f4240 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000555584b6f370 R13: 0000000000000005 R14: 00007fffe1fd34b0 R15: 00007fffe1fd34a0 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 2.054 msecs