rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=5689, q=83) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294997768-4294987266), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g5689 f0x2 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:28688 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4972 [inline] __schedule+0xa9a/0x4940 kernel/sched/core.c:6253 schedule+0xd2/0x260 kernel/sched/core.c:6326 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1955 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2128 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 0 CPU: 0 PID: 3867 Comm: syz-executor808 Not tainted 5.16.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation.cold+0x1fb/0x200 kernel/rcu/tree_stall.h:481 print_other_cpu_stall kernel/rcu/tree_stall.h:586 [inline] check_cpu_stall kernel/rcu/tree_stall.h:729 [inline] rcu_pending kernel/rcu/tree.c:3878 [inline] rcu_sched_clock_irq+0x2125/0x2200 kernel/rcu/tree.c:2597 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1428 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:tty_alloc_file drivers/tty/tty_io.c:191 [inline] RIP: 0010:tty_open+0x164/0x1000 drivers/tty/tty_io.c:2140 Code: 00 e8 00 1e 85 fd 48 85 c0 48 89 c3 0f 84 bb 0c 00 00 e8 3f b5 3e fd 4d 8d af b0 01 00 00 4c 89 e8 48 c1 e8 03 42 80 3c 30 00 <0f> 85 7f 0c 00 00 49 89 9f b0 01 00 00 8b 5c 24 38 bf 00 00 50 00 RSP: 0018:ffffc90002c9f8c8 EFLAGS: 00000246 RAX: 1ffff1100edff266 RBX: ffff88807a891880 RCX: 0000000000000000 RDX: ffff8880731a3a00 RSI: ffffffff8438f601 RDI: 0000000000000000 RBP: 0000000000000000 R08: 000000002654bddb R09: 0000000031af7b9f R10: 0000000000000001 R11: 0000000000000000 R12: 00000000fffffff5 R13: ffff888076ff9330 R14: dffffc0000000000 R15: ffff888076ff9180 chrdev_open+0x266/0x770 fs/char_dev.c:414 do_dentry_open+0x4c8/0x1250 fs/open.c:822 do_open fs/namei.c:3426 [inline] path_openat+0x1cad/0x2750 fs/namei.c:3559 do_filp_open+0x1aa/0x400 fs/namei.c:3586 do_sys_openat2+0x16d/0x4d0 fs/open.c:1212 do_sys_open fs/open.c:1228 [inline] __do_sys_openat fs/open.c:1244 [inline] __se_sys_openat fs/open.c:1239 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1239 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f6805a00af9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f68059b2318 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f6805a883e8 RCX: 00007f6805a00af9 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007f6805a883e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 7974742f7665642f R13: 00007ffc58b4f34f R14: 00007f68059b2400 R15: 0000000000022000 sched: RT throttling activated ---------------- Code disassembly (best guess): 0: 00 e8 add %ch,%al 2: 00 1e add %bl,(%rsi) 4: 85 fd test %edi,%ebp 6: 48 85 c0 test %rax,%rax 9: 48 89 c3 mov %rax,%rbx c: 0f 84 bb 0c 00 00 je 0xccd 12: e8 3f b5 3e fd callq 0xfd3eb556 17: 4d 8d af b0 01 00 00 lea 0x1b0(%r15),%r13 1e: 4c 89 e8 mov %r13,%rax 21: 48 c1 e8 03 shr $0x3,%rax 25: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1) * 2a: 0f 85 7f 0c 00 00 jne 0xcaf <-- trapping instruction 30: 49 89 9f b0 01 00 00 mov %rbx,0x1b0(%r15) 37: 8b 5c 24 38 mov 0x38(%rsp),%ebx 3b: bf 00 00 50 00 mov $0x500000,%edi