rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10499 ticks this GP) idle=522/1/0x4000000000000002 softirq=10976/10976 fqs=0 
	(t=10500 jiffies g=6225 q=97)
rcu: rcu_preempt kthread starved for 10500 jiffies! g6225 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29104    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081
 schedule+0x181/0x210 kernel/sched/core.c:4155
 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline]
 rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 0
CPU: 0 PID: 8169 Comm: udevd Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fb/0x318 lib/dump_stack.c:118
 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x15a/0x220 kernel/rcu/tree_stall.h:254
 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:529 [inline]
 rcu_pending kernel/rcu/tree.c:2827 [inline]
 rcu_sched_clock_irq+0xe25/0x1ad0 kernel/rcu/tree.c:2271
 update_process_times+0x12d/0x180 kernel/time/timer.c:1726
 tick_sched_handle kernel/time/tick-sched.c:167 [inline]
 tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310
 __run_hrtimer kernel/time/hrtimer.c:1514 [inline]
 __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1576
 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1638
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:free_thread_stack+0x18b/0x590 kernel/fork.c:284
Code: ff ff e8 28 04 00 00 43 80 3c 2e 00 74 08 4c 89 e7 e8 09 a4 69 00 49 8b 1c 24 48 83 c3 08 48 89 d8 48 c1 e8 03 42 80 3c 28 00 <74> 08 48 89 df e8 eb a3 69 00 48 8b 1b e9 82 ff ff ff e8 de 2c 2e
RSP: 0018:ffffc90001f576c8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff110128ac461 RBX: ffff888094562308 RCX: ffff888096934280
RDX: 0000000000000000 RSI: 00000000fffffffc RDI: ffffea00024e5780
RBP: ffffc90001f57700 R08: dffffc0000000000 R09: fffffbfff1287025
R10: fffffbfff1287025 R11: 0000000000000000 R12: ffff8880945623a0
R13: dffffc0000000000 R14: 1ffff110128ac474 R15: ffff8880949b7428
 release_task_stack kernel/fork.c:440 [inline]
 put_task_stack+0xa3/0x130 kernel/fork.c:451
 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256
 context_switch kernel/sched/core.c:3388 [inline]
 __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081
 preempt_schedule_irq+0xc1/0x140 kernel/sched/core.c:4338
 retint_kernel+0x1b/0x2b
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline]
RIP: 0010:kmem_cache_free+0xc8/0xf0 mm/slab.c:3695
Code: 58 07 00 74 42 4c 89 f7 57 9d 0f 1f 44 00 00 e8 0e 98 ca ff eb 19 e8 a7 95 ca ff 48 83 3d 07 f7 58 07 00 74 24 4c 89 f7 57 9d <0f> 1f 44 00 00 4c 89 e7 4c 89 fe e8 58 01 00 00 5b 41 5c 41 5e 41
RSP: 0018:ffffc90001f57910 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02
RAX: ffff888096934b14 RBX: ffff88821bc46700 RCX: ffffffff815c0597
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000286
RBP: ffffc90001f57930 R08: ffff888096934ad8 R09: fffffbfff13c852d
R10: fffffbfff13c852d R11: 0000000000000000 R12: ffffffff81a708d0
R13: ffff8880a86a7bd0 R14: 0000000000000286 R15: ffff8880a096c5b0
 anon_vma_chain_free mm/rmap.c:135 [inline]
 unlink_anon_vmas+0x310/0x690 mm/rmap.c:421
 free_pgtables+0x88/0x300 mm/memory.c:399
 exit_mmap+0x28a/0x530 mm/mmap.c:3141
 __mmput+0x120/0x3a0 kernel/fork.c:1082
 mmput+0x5d/0x70 kernel/fork.c:1103
 exec_mmap fs/exec.c:1047 [inline]
 flush_old_exec+0x551/0x6d0 fs/exec.c:1280
 load_elf_binary+0x652/0x3670 fs/binfmt_elf.c:847
 search_binary_handler+0x1a5/0x660 fs/exec.c:1658
 exec_binprm fs/exec.c:1701 [inline]
 __do_execve_file+0x1573/0x1cd0 fs/exec.c:1821
 do_execveat_common fs/exec.c:1867 [inline]
 do_execve fs/exec.c:1884 [inline]
 __do_sys_execve fs/exec.c:1960 [inline]
 __se_sys_execve fs/exec.c:1955 [inline]
 __x64_sys_execve+0x94/0xb0 fs/exec.c:1955
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f431fb6f207
Code: Bad RIP value.
RSP: 002b:00007ffcf3aa8c58 EFLAGS: 00000202 ORIG_RAX: 000000000000003b
RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007f431fb6f207
RDX: 0000000001e61880 RSI: 00007ffcf3aa8d50 RDI: 00007ffcf3aa9d60
RBP: 0000000000625500 R08: 000000000000112a R09: 000000000000112a
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000001e61880
R13: 0000000000000007 R14: 0000000001e50250 R15: 0000000000000005