rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 1, t=10502 jiffies, g=47065, q=72) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294996835-4294986332), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10504 jiffies! g47065 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:26544 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb72/0x1460 kernel/sched/core.c:6287 schedule+0x14b/0x210 kernel/sched/core.c:6366 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x1fd/0x770 kernel/rcu/tree.c:1957 rcu_gp_kthread+0xa5/0x350 kernel/rcu/tree.c:2130 kthread+0x453/0x480 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 1 CPU: 1 PID: 17000 Comm: syz-executor.5 Not tainted 5.15.0-rc6-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+0x1dc/0x2d8 lib/dump_stack.c:106 nmi_cpu_backtrace+0x45f/0x490 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x16a/0x280 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation+0x1ff/0x270 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:3880 [inline] rcu_sched_clock_irq+0x23d5/0x2bc0 kernel/rcu/tree.c:2599 update_process_times+0x197/0x200 kernel/time/timer.c:1785 tick_sched_handle kernel/time/tick-sched.c:226 [inline] tick_sched_timer+0x27d/0x420 kernel/time/tick-sched.c:1421 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x4cb/0xa60 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x3b3/0x1040 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0xf9/0x270 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0010:__schedule+0xb7a/0x1460 kernel/sched/core.c:6295 Code: 40 0a 00 00 fc 4c 89 fe 48 8d 94 24 a0 00 00 00 e8 6b d1 5f f7 48 8b 7c 24 08 4c 89 fe e8 4e 54 04 f7 48 89 c7 e8 46 16 5e f7 <48> c7 44 24 60 0e 36 e0 45 48 b8 00 00 00 00 00 fc ff df 48 8b 4c RSP: 0018:ffffc900039cf4c0 EFLAGS: 00000282 RAX: ec14fbb1d663a100 RBX: ffff8880b9d31558 RCX: ffffffff90933903 RDX: dffffc0000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900039cf5e0 R08: ffffffff818a06c0 R09: ffffed10173a62a9 R10: ffffed10173a62a9 R11: 0000000000000000 R12: 1ffff110173a6400 R13: 0000000000000000 R14: ffff8880b9d32000 R15: dffffc0000000000 schedule+0x14b/0x210 kernel/sched/core.c:6366 tty_open+0x9b0/0xdd0 drivers/tty/tty_io.c:2153 chrdev_open+0x5fb/0x680 fs/char_dev.c:414 do_dentry_open+0x7cb/0x1020 fs/open.c:822 do_open fs/namei.c:3428 [inline] path_openat+0x28b4/0x3670 fs/namei.c:3561 do_filp_open+0x277/0x4f0 fs/namei.c:3588 do_sys_openat2+0x13b/0x500 fs/open.c:1200 do_sys_open fs/open.c:1216 [inline] __do_sys_openat fs/open.c:1232 [inline] __se_sys_openat fs/open.c:1227 [inline] __x64_sys_openat+0x243/0x290 fs/open.c:1227 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f5a50ce2a39 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:00007f5a4e258188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f5a50de5f60 RCX: 00007f5a50ce2a39 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007f5a50d3ce8f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffea9cbda7f R14: 00007f5a4e258300 R15: 0000000000022000 ---------------- Code disassembly (best guess): 0: 40 0a 00 or (%rax),%al 3: 00 fc add %bh,%ah 5: 4c 89 fe mov %r15,%rsi 8: 48 8d 94 24 a0 00 00 lea 0xa0(%rsp),%rdx f: 00 10: e8 6b d1 5f f7 callq 0xf75fd180 15: 48 8b 7c 24 08 mov 0x8(%rsp),%rdi 1a: 4c 89 fe mov %r15,%rsi 1d: e8 4e 54 04 f7 callq 0xf7045470 22: 48 89 c7 mov %rax,%rdi 25: e8 46 16 5e f7 callq 0xf75e1670 * 2a: 48 c7 44 24 60 0e 36 movq $0x45e0360e,0x60(%rsp) <-- trapping instruction 31: e0 45 33: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 3a: fc ff df 3d: 48 rex.W 3e: 8b .byte 0x8b 3f: 4c rex.WR