rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10491 ticks this GP) idle=a02/1/0x4000000000000002 softirq=12839/12839 fqs=47 
	(t=10501 jiffies g=14393 q=172)
rcu: rcu_preempt kthread starved for 10404 jiffies! g14393 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29248    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x934/0x1f90 kernel/sched/core.c:4081
 schedule+0xdc/0x2b0 kernel/sched/core.c:4155
 schedule_timeout+0x49a/0xc60 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1668 [inline]
 rcu_gp_kthread+0xa10/0x1b20 kernel/rcu/tree.c:1835
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 1
CPU: 1 PID: 10154 Comm: syz-executor.4 Not tainted 5.5.0-rc2-next-20191220-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+0x197/0x210 lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x1a2/0x1ef kernel/rcu/tree_stall.h:254
 print_cpu_stall kernel/rcu/tree_stall.h:475 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:549 [inline]
 rcu_pending kernel/rcu/tree.c:3095 [inline]
 rcu_sched_clock_irq.cold+0x570/0xcc0 kernel/rcu/tree.c:2295
 update_process_times+0x2d/0x70 kernel/time/timer.c:1726
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167
 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1310
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline]
RIP: 0010:lock_is_held_type+0x272/0x320 kernel/locking/lockdep.c:4524
Code: ff df c7 83 9c 08 00 00 00 00 00 00 48 c1 e8 03 80 3c 10 00 0f 85 88 00 00 00 48 83 3d ce 30 39 08 00 74 31 48 8b 7d c0 57 9d <0f> 1f 44 00 00 48 83 c4 20 44 89 e0 5b 41 5c 41 5d 41 5e 41 5f 5d
RSP: 0018:ffffc900016d7538 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff13275cb RBX: ffff88804f5e0080 RCX: ffff88804f5e0920
RDX: dffffc0000000000 RSI: ffff888092f554f0 RDI: 0000000000000286
RBP: ffffc900016d7580 R08: ffff88804f5e0080 R09: ffffed1015d27074
R10: ffffed1015d27073 R11: ffff8880ae93839b R12: 0000000000000000
R13: ffff88804f5e0948 R14: ffff888092f554f0 R15: 0000000000000002
 lock_is_held include/linux/lockdep.h:361 [inline]
 xa_head include/linux/xarray.h:1129 [inline]
 xas_start+0x1af/0x560 lib/xarray.c:187
 xas_load+0x21/0x150 lib/xarray.c:232
 find_get_entry+0x14e/0x9e0 mm/filemap.c:1533
 pagecache_get_page+0x4c/0x9e0 mm/filemap.c:1635
 find_get_page include/linux/pagemap.h:260 [inline]
 generic_file_buffered_read mm/filemap.c:2047 [inline]
 generic_file_read_iter+0x722/0x2ac0 mm/filemap.c:2324
 ext4_file_read_iter fs/ext4/file.c:130 [inline]
 ext4_file_read_iter+0x1db/0x640 fs/ext4/file.c:113
 call_read_iter include/linux/fs.h:1895 [inline]
 generic_file_splice_read+0x4af/0x800 fs/splice.c:313
 do_splice_to+0x127/0x180 fs/splice.c:892
 splice_direct_to_actor+0x320/0xa30 fs/splice.c:971
 do_splice_direct+0x1da/0x2a0 fs/splice.c:1080
 do_sendfile+0x597/0xd00 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1519 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x15a/0x220 fs/read_write.c:1511
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a919
Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fd3beec4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a919
RDX: 00000000200001c0 RSI: 0000000000000005 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 00008080fffffffe R11: 0000000000000246 R12: 00007fd3beec56d4
R13: 00000000004c925e R14: 00000000004e0f88 R15: 00000000ffffffff