rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6821/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=270353, q=362 ncpus=1)
task:udevd           state:R  running task     stack:25752 pid:6821  tgid:6821  ppid:5237   task_flags:0x40014c flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7288
 irqentry_exit+0x36/0x90 kernel/entry/common.c:197
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:55 [inline]
RIP: 0010:stack_access_ok+0x2c/0x200 arch/x86/kernel/unwind_orc.c:393
Code: 00 00 00 00 00 fc ff df 41 57 41 56 4c 8d 77 08 41 55 41 54 49 89 d4 4c 89 f2 55 48 c1 ea 03 48 89 f5 53 48 89 fb 48 83 ec 08 <80> 3c 02 00 0f 85 94 01 00 00 4c 8d 6b 10 4c 8b 7b 08 48 b8 00 00
RSP: 0018:ffffc90003087718 EFLAGS: 00000296
RAX: dffffc0000000000 RBX: ffffc900030877c8 RCX: ffffffff9141d026
RDX: 1ffff92000610efa RSI: ffffc90003087de0 RDI: ffffc900030877c8
RBP: ffffc90003087de0 R08: ffffffff9141d02a R09: 0000000000000000
R10: 0000000000000001 R11: 000000000000794a R12: 0000000000000008
R13: ffffc900030877c8 R14: ffffc900030877d0 R15: ffffc900030877fc
 deref_stack_reg arch/x86/kernel/unwind_orc.c:403 [inline]
 unwind_next_frame+0xcfe/0x20a0 arch/x86/kernel/unwind_orc.c:585
 arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:548
 __call_rcu_common.constprop.0+0xa5/0xa10 kernel/rcu/tree.c:3123
 slab_free_hook mm/slub.c:2386 [inline]
 slab_free mm/slub.c:4695 [inline]
 kmem_cache_free+0x16d/0x4d0 mm/slub.c:4797
 exit_mmap+0x511/0xb90 mm/mmap.c:1305
 __mmput+0x12a/0x410 kernel/fork.c:1129
 mmput+0x62/0x70 kernel/fork.c:1152
 exit_mm kernel/exit.c:582 [inline]
 do_exit+0x7c7/0x2bf0 kernel/exit.c:949
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 __do_sys_exit_group kernel/exit.c:1113 [inline]
 __se_sys_exit_group kernel/exit.c:1111 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1111
 x64_sys_call+0x14fa/0x1720 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7ee12f16c5
RSP: 002b:00007ffec6c91618 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000056260fbb4040 RCX: 00007f7ee12f16c5
RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000
RBP: 000056260fb92910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffec6c91660 R14: 0000000000000000 R15: 0000000000000000
 </TASK>