rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3623/1:b..l
	(detected by 0, t=10502 jiffies, g=11797, q=663 ncpus=2)
task:udevd           state:R  running task     stack:22600 pid:3623  ppid:1      flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6558
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6870
 irqentry_exit+0x53/0x80 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_acquire+0x26f/0x5a0 kernel/locking/lockdep.c:5666
Code: 2b 00 74 08 4c 89 f7 e8 ff 8b 77 00 f6 44 24 61 02 0f 85 84 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc9000e37f8c0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff92001c6ff24 RCX: 1ffff92001c6fec4
RDX: dffffc0000000000 RSI: ffffffff8b0c14c0 RDI: ffffffff8b5e6980
RBP: ffffc9000e37fa10 R08: dffffc0000000000 R09: fffffbfff224a04d
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92001c6ff20
R13: dffffc0000000000 R14: ffffc9000e37f920 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 __d_lookup+0xa8/0x790 fs/dcache.c:2488
 lookup_fast+0x74/0x490 fs/namei.c:1648
 walk_component+0x57/0x400 fs/namei.c:1994
 lookup_last fs/namei.c:2455 [inline]
 path_lookupat+0x16f/0x450 fs/namei.c:2479
 filename_lookup+0x251/0x600 fs/namei.c:2508
 user_path_at_empty+0x3e/0x60 fs/namei.c:2905
 do_readlinkat+0x114/0x3a0 fs/stat.c:468
 __do_sys_readlink fs/stat.c:501 [inline]
 __se_sys_readlink fs/stat.c:498 [inline]
 __x64_sys_readlink+0x7b/0x90 fs/stat.c:498
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f97fe117d47
RSP: 002b:00007ffc7e26bc98 EFLAGS: 00000246 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00007ffc7e26bca8 RCX: 00007f97fe117d47
RDX: 0000000000000400 RSI: 00007ffc7e26bca8 RDI: 00007ffc7e26c188
RBP: 0000000000000400 R08: 00005624c2a66ac4 R09: 0000000000000000
R10: 0000000000000812 R11: 0000000000000246 R12: 00007ffc7e26c188
R13: 00007ffc7e26c0f8 R14: 00005624c2a35910 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 9627 jiffies! g11797 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:25528 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6558
 schedule+0xbf/0x180 kernel/sched/core.c:6634
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2d2/0x1150 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0xa3/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:567