rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=8bb/1 softirq=73756/73757 fqs=5 
	(t=10501 jiffies g=150625 q=62)
rcu: rcu_preempt kthread starved for 10491 jiffies! g150625 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    24168    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3430 [inline]
 __schedule+0x8f3/0x1f80 kernel/sched/core.c:4155
 schedule+0xd0/0x2a0 kernel/sched/core.c:4230
 schedule_timeout+0x359/0x850 kernel/time/timer.c:1897
 rcu_gp_fqs_loop kernel/rcu/tree.c:1805 [inline]
 rcu_gp_kthread+0xc5a/0x19e0 kernel/rcu/tree.c:1975
 kthread+0x3b5/0x4a0 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
NMI backtrace for cpu 1
CPU: 1 PID: 3777 Comm: syz-executor.0 Not tainted 5.7.0-rc7-next-20200529-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+0x18f/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1e6/0x221 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:165 [inline]
 rcu_dump_cpu_stacks+0x19b/0x1e5 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:3421 [inline]
 rcu_sched_clock_irq.cold+0x55a/0xd33 kernel/rcu/tree.c:2436
 update_process_times+0x25/0x60 kernel/time/timer.c:1726
 tick_sched_handle.isra.0+0x91/0x180 kernel/time/tick-sched.c:176
 tick_sched_timer+0x50/0x140 kernel/time/tick-sched.c:1328
 __run_hrtimer kernel/time/hrtimer.c:1520 [inline]
 __hrtimer_run_queues+0x5ca/0xea0 kernel/time/hrtimer.c:1584
 hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1646
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline]
 __sysvec_apic_timer_interrupt+0x142/0x5e0 arch/x86/kernel/apic/apic.c:1097
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:719
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 sysvec_apic_timer_interrupt+0x207/0x260 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:576
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:765 [inline]
RIP: 0010:lock_acquire+0x267/0x8f0 kernel/locking/lockdep.c:4962
Code: 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 0f 85 c3 05 00 00 48 83 3d 35 65 5b 08 00 0f 84 62 04 00 00 48 8b 3c 24 57 9d <0f> 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 48 03 44 24 08 48 c7
RSP: 0018:ffffc90007dff3c8 EFLAGS: 00000282
RAX: 1ffffffff1369538 RBX: ffff88808cc7e500 RCX: 0000000000000001
RDX: dffffc0000000000 RSI: 000000006bcf50ba RDI: 0000000000000282
RBP: 0000000000000000 R08: 0000000000000001 R09: fffffbfff18b1145
R10: ffffffff8c588a27 R11: fffffbfff18b1144 R12: 0000000000000002
R13: ffffffff89bbde00 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:241 [inline]
 rcu_read_lock include/linux/rcupdate.h:634 [inline]
 wb_get_create_current include/linux/backing-dev.h:303 [inline]
 balance_dirty_pages_ratelimited+0x673/0x1bc0 mm/page-writeback.c:1872
 generic_perform_write+0x325/0x4e0 mm/filemap.c:3373
 ext4_buffered_write_iter+0x1f7/0x450 fs/ext4/file.c:270
 ext4_file_write_iter+0x1ec/0x13f0 fs/ext4/file.c:649
 call_write_iter include/linux/fs.h:1926 [inline]
 do_iter_readv_writev+0x51e/0x790 fs/read_write.c:694
 do_iter_write fs/read_write.c:999 [inline]
 do_iter_write+0x18b/0x600 fs/read_write.c:980
 vfs_iter_write+0x70/0xa0 fs/read_write.c:1040
 iter_file_splice_write+0x695/0xb10 fs/splice.c:750
 do_splice_from+0x86/0x110 fs/splice.c:846
 direct_splice_actor+0xa3/0x110 fs/splice.c:1016
 splice_direct_to_actor+0x38c/0x980 fs/splice.c:971
 do_splice_direct+0x1b4/0x280 fs/splice.c:1059
 do_sendfile+0x555/0xc50 fs/read_write.c:1521
 __do_sys_sendfile64 fs/read_write.c:1576 [inline]
 __se_sys_sendfile64 fs/read_write.c:1568 [inline]
 __x64_sys_sendfile64+0x149/0x210 fs/read_write.c:1568
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45ca69
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f87b028fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00000000004fcec0 RCX: 000000000045ca69
RDX: 00000000200001c0 RSI: 0000000000000003 RDI: 0000000000000003
RBP: 000000000078c040 R08: 0000000000000000 R09: 0000000000000000
R10: 00008080fffffffe R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008f3 R14: 00000000004cbc4a R15: 00007f87b02906d4