rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 1, t=10502 jiffies, g=11985, q=18) rcu: All QSes seen, last rcu_preempt kthread activity 8612 (4294978939-4294970327), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 8612 jiffies! g11985 f0x2 RCU_GP_CLEANUP(7) ->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:28952 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0x940/0x26f0 kernel/sched/core.c:6287 preempt_schedule_common+0x45/0xc0 kernel/sched/core.c:6459 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline] _raw_spin_unlock_irq+0x3c/0x40 kernel/locking/spinlock.c:202 rcu_gp_cleanup+0x26c/0xb30 kernel/rcu/tree.c:2061 rcu_gp_kthread+0x1ef/0x320 kernel/rcu/tree.c:2134 kthread+0x3e5/0x4d0 kernel/kthread.c:319 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 1 CPU: 1 PID: 6673 Comm: syz-executor055 Not tainted 5.15.0-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:105 nmi_trigger_cpumask_backtrace+0x1ae/0x220 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:3880 [inline] rcu_sched_clock_irq+0x2125/0x2200 kernel/rcu/tree.c:2599 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:1421 __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:__schedule+0x948/0x26f0 kernel/sched/core.c:6166 Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 cb 17 00 00 4c 89 ef 4d 89 7c 24 10 4c 89 fe e8 20 8c c9 f7 48 89 c7 e8 38 72 18 f8 <48> 8b 8d 38 ff ff ff 48 b8 00 00 00 00 00 fc ff df 48 c7 04 01 00 RSP: 0018:ffffc900030b77c0 EFLAGS: 00000206 RAX: 0000000000d8a0eb RBX: 0000000000000000 RCX: 1ffffffff1adbf69 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900030b7888 R08: 0000000000000001 R09: 0000000000000001 R10: ffffffff817b5f48 R11: 0000000000000000 R12: ffff8880b9d31ac0 R13: ffff8880b9d32580 R14: 0000000000000001 R15: ffff8880763c4200 schedule+0xd3/0x270 kernel/sched/core.c:6366 tty_open+0x885/0x1000 drivers/tty/tty_io.c:2153 chrdev_open+0x266/0x770 fs/char_dev.c:414 do_dentry_open+0x4c8/0x11d0 fs/open.c:822 do_open fs/namei.c:3428 [inline] path_openat+0x1c9a/0x2740 fs/namei.c:3561 do_filp_open+0x1aa/0x400 fs/namei.c:3588 do_sys_openat2+0x16d/0x4d0 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+0x13f/0x1f0 fs/open.c:1227 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: 0033:0x7f32873feaf9 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:00007f32873b0318 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f32874863e8 RCX: 00007f32873feaf9 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007f32874863e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 7974742f7665642f R13: 00007fff74f6908f R14: 00007f32873b0400 R15: 0000000000022000 ---------------- Code disassembly (best guess): 0: df 48 89 fisttps -0x77(%rax) 3: fa cli 4: 48 c1 ea 03 shr $0x3,%rdx 8: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) c: 0f 85 cb 17 00 00 jne 0x17dd 12: 4c 89 ef mov %r13,%rdi 15: 4d 89 7c 24 10 mov %r15,0x10(%r12) 1a: 4c 89 fe mov %r15,%rsi 1d: e8 20 8c c9 f7 callq 0xf7c98c42 22: 48 89 c7 mov %rax,%rdi 25: e8 38 72 18 f8 callq 0xf8187262 * 2a: 48 8b 8d 38 ff ff ff mov -0xc8(%rbp),%rcx <-- trapping instruction 31: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 38: fc ff df 3b: 48 rex.W 3c: c7 .byte 0xc7 3d: 04 01 add $0x1,%al