rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=8de/1/0x4000000000000000 softirq=9268/9294 fqs=0 
	(t=17067 jiffies g=3897 q=544)
rcu: rcu_preempt kthread starved for 17067 jiffies! g3897 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
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:I stack:14328 pid:   10 ppid:     2 flags:0x00004000
Call Trace:
 context_switch kernel/sched/core.c:3774 [inline]
 __schedule+0x404/0x890 kernel/sched/core.c:4523
 schedule+0x38/0xe0 kernel/sched/core.c:4601
 schedule_timeout+0x1be/0x2e0 kernel/time/timer.c:1871
 rcu_gp_fqs_loop kernel/rcu/tree.c:1925 [inline]
 rcu_gp_kthread+0x707/0xc60 kernel/rcu/tree.c:2099
 kthread+0x145/0x170 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
NMI backtrace for cpu 1
CPU: 1 PID: 7 Comm: kworker/u4:0 Not tainted 5.10.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xa3/0xc8 lib/dump_stack.c:118
 nmi_cpu_backtrace.cold.8+0x53/0x6d lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0xd5/0xf0 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0xa2/0xce kernel/rcu/tree_stall.h:318
 print_cpu_stall kernel/rcu/tree_stall.h:551 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:625 [inline]
 rcu_pending kernel/rcu/tree.c:3694 [inline]
 rcu_sched_clock_irq.cold.93+0x61/0x52b kernel/rcu/tree.c:2567
 update_process_times+0x50/0x80 kernel/time/timer.c:1709
 tick_sched_handle.isra.24+0x1a/0x50 kernel/time/tick-sched.c:176
 tick_sched_timer+0x6c/0x80 kernel/time/tick-sched.c:1328
 __run_hrtimer kernel/time/hrtimer.c:1519 [inline]
 __hrtimer_run_queues+0x1e3/0x4f0 kernel/time/hrtimer.c:1583
 hrtimer_interrupt+0xf9/0x210 kernel/time/hrtimer.c:1645
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline]
 __sysvec_apic_timer_interrupt+0x8e/0x290 arch/x86/kernel/apic/apic.c:1097
 asm_call_irq_on_stack+0xf/0x20
 </IRQ>
 __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline]
 run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline]
 sysvec_apic_timer_interrupt+0xcc/0xf0 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:653 [inline]
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x32/0x70 kernel/locking/spinlock.c:191
Code: 53 48 89 f3 48 8b 74 24 10 e8 0a f8 15 fe 48 89 ef e8 e2 3c 16 fe f6 c7 02 75 2c 48 83 3d ed 6f 1f 01 00 74 31 48 89 df 57 9d <0f> 1f 44 00 00 bf 01 00 00 00 e8 9f 99 12 fe 65 8b 05 08 2b f4 7c
RSP: 0018:ffffc90000ca3800 EFLAGS: 00000282
RAX: 00000000000b3dfb RBX: 0000000000000282 RCX: 0000000000000007
RDX: 0000000000000000 RSI: ffffffff83f3001b RDI: 0000000000000282
RBP: ffff88810f35d7e8 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 00000000000317c8 R12: 0000000000000000
R13: ffff888100e9d000 R14: ffff88810f35d5b8 R15: ffff88810f35d7e0
 spin_unlock_irqrestore include/linux/spinlock.h:409 [inline]
 __test_set_page_writeback+0x205/0x510 mm/page-writeback.c:2809
 set_page_writeback include/linux/page-flags.h:563 [inline]
 ext4_bio_write_page+0x9e/0x590 fs/ext4/page-io.c:458
 mpage_submit_page+0x5c/0x80 fs/ext4/inode.c:2090
 mpage_map_and_submit_buffers+0x169/0x270 fs/ext4/inode.c:2338
 mpage_map_and_submit_extent fs/ext4/inode.c:2477 [inline]
 ext4_writepages+0xa55/0x11a0 fs/ext4/inode.c:2790
 do_writepages+0x39/0xe0 mm/page-writeback.c:2352
 __writeback_single_inode+0x5d/0x670 fs/fs-writeback.c:1461
 writeback_sb_inodes+0x1fb/0x510 fs/fs-writeback.c:1721
 __writeback_inodes_wb+0x5a/0xc0 fs/fs-writeback.c:1790
 wb_writeback+0x32a/0x4c0 fs/fs-writeback.c:1896
 wb_check_old_data_flush fs/fs-writeback.c:1998 [inline]
 wb_do_writeback fs/fs-writeback.c:2051 [inline]
 wb_workfn+0x49d/0x6f0 fs/fs-writeback.c:2080
 process_one_work+0x273/0x600 kernel/workqueue.c:2272
 worker_thread+0x38/0x380 kernel/workqueue.c:2418
 kthread+0x145/0x170 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296