rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 0, t=10502 jiffies, g=6173, q=12 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10501 (4294965706-4294955205), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g6173 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:24656 pid:16 tgid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5409 [inline] __schedule+0x1781/0x49d0 kernel/sched/core.c:6736 __schedule_loop kernel/sched/core.c:6813 [inline] schedule+0x14b/0x320 kernel/sched/core.c:6828 schedule_timeout+0x1be/0x310 kernel/time/timer.c:2572 rcu_gp_fqs_loop+0x2df/0x1370 kernel/rcu/tree.c:1663 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:1862 kthread+0x2f0/0x390 kernel/kthread.c:388 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243 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: 5103 Comm: syz-executor398 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 RIP: 0010:get_current arch/x86/include/asm/current.h:49 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70 kernel/kcov.c:206 Code: 8b 3d 6c cd 1a 0c 48 89 de 5b e9 03 ad 54 00 0f 1f 00 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 40 d0 03 00 65 8b 15 e0 db 6e 7e f7 c2 00 01 ff 00 RSP: 0018:ffffc90000a08bd0 EFLAGS: 00000002 RAX: ffffffff815ba4a8 RBX: 0000000000000001 RCX: ffff88801835bc00 RDX: ffff88801835bc00 RSI: ffffffff8bfdfee0 RDI: ffffffff8bfdfea0 RBP: ffffc90000a08c80 R08: ffffffff815ba496 R09: fffff52000141158 R10: dffffc0000000000 R11: fffff52000141158 R12: ffff888029209bc0 R13: 1ffff1100306b8a2 R14: ffff88801835c510 R15: 1ffff92000141190 FS: 000055556344b3c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f57d09fe4c0 CR3: 000000007cdc8000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_read_unlock include/linux/rcupdate.h:779 [inline] __lock_task_sighand+0x238/0x2e0 kernel/signal.c:1419 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+0x595/0xd00 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+0x107/0x3a0 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 da 67 fb f5 48 89 df e8 92 a7 fc f5 e8 fd cc 25 f6 fb bf 01 00 00 00 22 94 ee f5 65 8b 05 33 79 8d 74 85 c0 74 06 5b c3 cc cc cc cc RSP: 0018:ffffc9000460fc70 EFLAGS: 00000282 RAX: b46a0e4d4379ac00 RBX: ffff888029209bc0 RCX: ffffffff944a6603 RDX: dffffc0000000000 RSI: ffffffff8baac1e0 RDI: 0000000000000001 RBP: ffffc9000460fdb0 R08: ffffffff8f860def R09: 1ffffffff1f0c1bd R10: dffffc0000000000 R11: fffffbfff1f0c1be R12: 1ffff1100524140b R13: 000000001c000004 R14: 0000000000000021 R15: ffff88802920a058 spin_unlock_irq include/linux/spinlock.h:401 [inline] get_signal+0x156e/0x1850 kernel/signal.c:2910 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop kernel/entry/common.c:105 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:201 [inline] syscall_exit_to_user_mode+0xc9/0x360 kernel/entry/common.c:212 do_syscall_64+0x10a/0x240 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x6d/0x75 RIP: 0033:0x7f57d09e6e79 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:00007ffd49b88a68 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007f57d09e6e79 RDX: 000000002006b000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00000000000f4240 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000001 R14: 00007ffd49b88ae0 R15: 00007ffd49b88ad0 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.626 msecs