rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (10499 ticks this GP) idle=90e/1/0x4000000000000002 softirq=12581/12584 fqs=2784 
	(t=10500 jiffies g=6921 q=148)
rcu: rcu_preempt kthread starved for 4912 jiffies! g6921 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29032    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 1
CPU: 1 PID: 8486 Comm: syz-executor.0 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+0x151/0x590 kernel/fork.c:280
Code: 31 f6 e8 42 af 6e 00 43 80 3c 2e 00 74 08 4c 89 e7 e8 43 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 25 a4 69 00 48 8b 3b be fc ff ff ff e8 28 04 00
RSP: 0018:ffffc900020178e8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11014a21861 RBX: ffff8880a510c308 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0002897d40
RBP: ffffc90002017920 R08: 000000000003a768 R09: fffffbfff120248a
R10: fffffbfff120248a R11: 0000000000000000 R12: ffff8880a510c3a0
R13: dffffc0000000000 R14: 1ffff11014a21874 R15: ffff8880a73b5428
 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:slab_alloc mm/slab.c:3313 [inline]
RIP: 0010:kmem_cache_alloc+0x1a8/0x2e0 mm/slab.c:3484
Code: 8b 7d d0 57 9d 0f 1f 44 00 00 e8 83 b1 ca ff eb 1e e8 1c af ca ff 48 83 3d 7c 10 59 07 00 0f 84 33 01 00 00 48 8b 7d d0 57 9d <0f> 1f 44 00 00 41 0f 18 0e e9 21 00 00 00 89 d8 c1 e8 08 83 e0 01
RSP: 0018:ffffc90002017b38 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: ffff888098948cd4 RBX: 0000000000000c40 RCX: ffffffff815c0597
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000286
RBP: ffffc90002017b70 R08: ffff888098948c98 R09: fffffbfff13c852e
R10: fffffbfff13c852e R11: 0000000000000000 R12: ffff8882194dc380
R13: ffff8880a8b33a80 R14: ffff8880a5409040 R15: 0000000000000c40
 ext4_alloc_inode+0x1f/0x560 fs/ext4/super.c:1073
 alloc_inode fs/inode.c:230 [inline]
 new_inode_pseudo+0x68/0x240 fs/inode.c:919
 new_inode+0x28/0x1c0 fs/inode.c:948
 __ext4_new_inode+0x43d/0x56a0 fs/ext4/ialloc.c:824
 ext4_symlink+0x52a/0xf60 fs/ext4/namei.c:3275
 vfs_symlink+0x36f/0x4f0 fs/namei.c:4123
 do_symlinkat+0x187/0x3f0 fs/namei.c:4150
 __do_sys_symlink fs/namei.c:4169 [inline]
 __se_sys_symlink fs/namei.c:4167 [inline]
 __x64_sys_symlink+0x60/0x70 fs/namei.c:4167
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a3a7
Code: 0f 1f 00 b8 5c 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 6d b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 58 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 4d b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffcb6f20038 EFLAGS: 00000202 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045a3a7
RDX: 00007ffcb6f200d7 RSI: 00000000004c00d3 RDI: 00007ffcb6f200c0
RBP: 0000000000000000 R08: 0000000000000220 R09: 0000000000000017
R10: 0000000000000075 R11: 0000000000000202 R12: 0000000000000001
R13: 00007ffcb6f20070 R14: 0000000000000000 R15: 00007ffcb6f20080