rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=57321, q=421) rcu: All QSes seen, last rcu_preempt kthread activity 10474 (4294992570-4294982096), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10474 jiffies! g57321 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:28896 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: 9523 Comm: syz-executor.5 Not tainted 5.16.0-rc5-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_open_by_driver drivers/tty/tty_io.c:2064 [inline] RIP: 0010:tty_open+0x56d/0x1000 drivers/tty/tty_io.c:2146 Code: e8 28 03 3e fd 31 f6 48 c7 c7 20 60 5a 8c c7 44 24 68 ff ff ff ff e8 02 8a 0d 05 89 df 4c 89 fe 48 8d 54 24 68 e8 e3 bf ff ff <48> c7 c7 00 f0 ff ff 48 89 c5 48 89 c6 48 89 44 24 10 48 89 c3 e8 RSP: 0018:ffffc9000b70f8c8 EFLAGS: 00000246 RAX: ffff88801b0e0100 RBX: 0000000000400043 RCX: ffffc90003e29000 RDX: 0000000000040000 RSI: ffffffff8438a374 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: ffff88801b0e0107 R10: ffffffff8438a35d R11: 0000000000400043 R12: 00000000fffffff5 R13: ffff8880248954f0 R14: dffffc0000000000 R15: ffff888024895340 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: 0033:0x7f3e1f233e99 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3e1dba9168 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f3e1f346f60 RCX: 00007f3e1f233e99 RDX: 0000000000000000 RSI: 0000000020000000 RDI: ffffffffffffff9c RBP: 00007f3e1f28dff1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc7fb7a79f R14: 00007f3e1dba9300 R15: 0000000000022000 ---------------- Code disassembly (best guess): 0: e8 28 03 3e fd callq 0xfd3e032d 5: 31 f6 xor %esi,%esi 7: 48 c7 c7 20 60 5a 8c mov $0xffffffff8c5a6020,%rdi e: c7 44 24 68 ff ff ff movl $0xffffffff,0x68(%rsp) 15: ff 16: e8 02 8a 0d 05 callq 0x50d8a1d 1b: 89 df mov %ebx,%edi 1d: 4c 89 fe mov %r15,%rsi 20: 48 8d 54 24 68 lea 0x68(%rsp),%rdx 25: e8 e3 bf ff ff callq 0xffffc00d * 2a: 48 c7 c7 00 f0 ff ff mov $0xfffffffffffff000,%rdi <-- trapping instruction 31: 48 89 c5 mov %rax,%rbp 34: 48 89 c6 mov %rax,%rsi 37: 48 89 44 24 10 mov %rax,0x10(%rsp) 3c: 48 89 c3 mov %rax,%rbx 3f: e8 .byte 0xe8