rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P2963/1:b..l (detected by 1, t=10502 jiffies, g=148437, q=233) task:udevd state:R running task stack:22176 pid: 2963 ppid: 1 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5073 [inline] __schedule+0x939/0xea0 kernel/sched/core.c:6388 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6696 irqentry_exit+0x56/0x90 kernel/entry/common.c:428 asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0010:__legitimize_mnt+0x56/0x180 fs/namespace.c:632 Code: 49 bc 00 00 00 00 00 fc ff df 49 8d 5f 30 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 60 bd e9 ff 48 8b 03 65 ff 00 83 44 24 fc 00 8b 1d 2e 20 94 0a 89 df 89 ee e8 95 d9 98 ff 39 RSP: 0018:ffffc90002baf960 EFLAGS: 00000206 RAX: 0000607f4620a014 RBX: ffff8880121dac50 RCX: 0000000000000000 RDX: ffff88807c5d8000 RSI: 000000000000e60e RDI: 000000000000e60e RBP: 000000000000e60e R08: ffffffff81ed26d3 R09: ffffc90002baf920 R10: fffff52000575f2d R11: 1ffff92000575f24 R12: dffffc0000000000 R13: dffffc0000000000 R14: 0000000000000002 R15: ffff8880121dac20 __legitimize_path fs/namei.c:691 [inline] legitimize_path fs/namei.c:708 [inline] try_to_unlazy+0x3ab/0xaa0 fs/namei.c:777 may_lookup fs/namei.c:1734 [inline] link_path_walk+0x296/0xd80 fs/namei.c:2289 path_lookupat+0xab/0x450 fs/namei.c:2498 filename_lookup+0x277/0x640 fs/namei.c:2528 user_path_at_empty+0x40/0x1a0 fs/namei.c:2851 do_readlinkat+0x11b/0x3b0 fs/stat.c:456 __do_sys_readlink fs/stat.c:489 [inline] __se_sys_readlink fs/stat.c:486 [inline] __x64_sys_readlink+0x7b/0x90 fs/stat.c:486 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7ff43cb27277 RSP: 002b:00007fff6b8f5df8 EFLAGS: 00000202 ORIG_RAX: 0000000000000059 RAX: ffffffffffffffda RBX: 00007fff6b8f6618 RCX: 00007ff43cb27277 RDX: 0000000000000200 RSI: 00007fff6b8f5e08 RDI: 00007fff6b8f6008 RBP: 0000557280f1f910 R08: 0000000000000000 R09: 00007fff6b8f5ca0 R10: 00000000000019c0 R11: 0000000000000202 R12: 00007fff6b8f5e08 R13: 00007fff6b8f6008 R14: 0000000000000000 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 10219 jiffies! g148437 f0x0 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:26424 pid: 16 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5073 [inline] __schedule+0x939/0xea0 kernel/sched/core.c:6388 schedule+0xeb/0x1b0 kernel/sched/core.c:6460 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1884 rcu_gp_fqs_loop+0x2b9/0xfb0 kernel/rcu/tree.c:1971 rcu_gp_kthread+0xa5/0x360 kernel/rcu/tree.c:2144 kthread+0x266/0x300 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Tainted: G S 5.18.0-rc3-syzkaller-00190-gc00c5e1d157b #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+0x1e3/0x2cb lib/dump_stack.c:106 nmi_cpu_backtrace+0x473/0x4a0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x168/0x280 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation+0x1da/0x250 kernel/rcu/tree_stall.h:490 print_other_cpu_stall+0x13fa/0x1550 kernel/rcu/tree_stall.h:595 check_cpu_stall kernel/rcu/tree_stall.h:741 [inline] rcu_pending kernel/rcu/tree.c:3923 [inline] rcu_sched_clock_irq+0x928/0x18d0 kernel/rcu/tree.c:2625 update_process_times+0x197/0x200 kernel/time/timer.c:1788 tick_sched_handle kernel/time/tick-sched.c:243 [inline] tick_sched_timer+0x377/0x540 kernel/time/tick-sched.c:1473 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x4cb/0xa60 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x3a6/0xfd0 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0xf9/0x280 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:native_save_fl arch/x86/include/asm/irqflags.h:22 [inline] RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline] RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:130 [inline] RIP: 0010:acpi_safe_halt drivers/acpi/processor_idle.c:116 [inline] RIP: 0010:acpi_idle_do_entry drivers/acpi/processor_idle.c:556 [inline] RIP: 0010:acpi_idle_enter+0x42d/0x790 drivers/acpi/processor_idle.c:691 Code: fc 48 83 e3 08 44 8b 7c 24 04 0f 85 22 01 00 00 4c 8d 74 24 40 e8 93 fd 00 fd eb 0c e8 ac 59 fa fc 0f 00 2d f5 a1 68 06 fb f4 <4c> 89 f3 48 c1 eb 03 42 80 3c 23 00 74 08 4c 89 f7 e8 5d 3f 4b fd RSP: 0018:ffffc90000d77c00 EFLAGS: 00000286 RAX: 6b78443496649d00 RBX: 0000000000000000 RCX: ffffffff90b7a603 RDX: dffffc0000000000 RSI: ffffffff8a8d0480 RDI: ffffffff8ae88c20 RBP: ffffc90000d77cb0 R08: ffffffff818ca320 R09: ffffed10024093b1 R10: ffffed10024093b1 R11: 1ffff110024093b0 R12: dffffc0000000000 R13: ffff8880115be064 R14: ffffc90000d77c40 R15: 0000000000000001 cpuidle_enter_state+0x517/0xed0 drivers/cpuidle/cpuidle.c:237 cpuidle_enter+0x59/0x90 drivers/cpuidle/cpuidle.c:351 call_cpuidle kernel/sched/idle.c:155 [inline] cpuidle_idle_call kernel/sched/idle.c:236 [inline] do_idle+0x3d2/0x640 kernel/sched/idle.c:303 cpu_startup_entry+0x15/0x20 kernel/sched/idle.c:400 secondary_startup_64_no_verify+0xc4/0xcb ---------------- Code disassembly (best guess): 0: 49 bc 00 00 00 00 00 movabs $0xdffffc0000000000,%r12 7: fc ff df a: 49 8d 5f 30 lea 0x30(%r15),%rbx e: 48 89 d8 mov %rbx,%rax 11: 48 c1 e8 03 shr $0x3,%rax 15: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) 1a: 74 08 je 0x24 1c: 48 89 df mov %rbx,%rdi 1f: e8 60 bd e9 ff callq 0xffe9bd84 24: 48 8b 03 mov (%rbx),%rax 27: 65 ff 00 incl %gs:(%rax) * 2a: f0 83 44 24 fc 00 lock addl $0x0,-0x4(%rsp) <-- trapping instruction 30: 8b 1d 2e 20 94 0a mov 0xa94202e(%rip),%ebx # 0xa942064 36: 89 df mov %ebx,%edi 38: 89 ee mov %ebp,%esi 3a: e8 95 d9 98 ff callq 0xff98d9d4 3f: 39 .byte 0x39