rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10499 ticks this GP) idle=5ca/1/0x4000000000000002 softirq=27623/27623 fqs=0 
	(t=10501 jiffies g=23877 q=97)
rcu: rcu_preempt kthread starved for 10502 jiffies! g23877 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29384    10      2 0x80004000
Call Trace:
 schedule+0xd0/0x2a0 kernel/sched/core.c:4154
 schedule_timeout+0x474/0xba0 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1658 [inline]
 rcu_gp_kthread+0x9d9/0x17d0 kernel/rcu/tree.c:1818
 kthread+0x357/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 1
CPU: 1 PID: 12485 Comm: syz-executor.3 Not tainted 5.6.0-rc5-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+0x188/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x169/0x1b3 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:3030 [inline]
 rcu_sched_clock_irq.cold+0x518/0xc55 kernel/rcu/tree.c:2276
 update_process_times+0x25/0x60 kernel/time/timer.c:1726
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:171
 tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1314
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x32c/0xdd0 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline]
 smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1144
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:rcu_read_lock_held+0x2c/0xb0 kernel/rcu/update.c:278
Code: 00 00 00 00 00 fc ff df 53 48 83 ec 60 48 c7 04 24 b3 8a b5 41 48 89 e3 48 c7 44 24 08 4f c4 24 89 48 8d 7c 24 20 48 c1 eb 03 <48> c7 44 24 10 60 bf 5e 81 48 01 d8 c7 00 f1 f1 f1 f1 c7 40 04 01
RSP: 0018:ffffc900083d7588 EFLAGS: 00000a06 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: 1ffff9200107aeb1 RCX: ffffc90010a30000
RDX: 0000000000040000 RSI: ffffffff87b80877 RDI: ffffc900083d75a8
RBP: 0000000000000033 R08: ffff888069242580 R09: ffffed1015ce7074
R10: ffffed1015ce7073 R11: ffff8880ae73839b R12: ffff888092367700
R13: ffff888092324742 R14: 0000000000000000 R15: ffff888092324742
 xa_entry include/linux/xarray.h:1180 [inline]
 xas_descend+0x2bc/0x360 lib/xarray.c:204
 xas_load+0xe5/0x140 lib/xarray.c:240
 find_get_entry+0x138/0x770 mm/filemap.c:1511
 pagecache_get_page+0x47/0xa10 mm/filemap.c:1613
 find_get_page include/linux/pagemap.h:260 [inline]
 generic_file_buffered_read mm/filemap.c:2025 [inline]
 generic_file_read_iter+0x6ae/0x2a40 mm/filemap.c:2302
 ext4_file_read_iter fs/ext4/file.c:131 [inline]
 ext4_file_read_iter+0x1d1/0x600 fs/ext4/file.c:114
 call_read_iter include/linux/fs.h:1895 [inline]
 generic_file_splice_read+0x473/0x770 fs/splice.c:313
 do_splice_to+0x10e/0x160 fs/splice.c:892
 splice_direct_to_actor+0x307/0x980 fs/splice.c:971
 do_splice_direct+0x1a8/0x270 fs/splice.c:1080
 do_sendfile+0x549/0xc40 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1575 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0x149/0x210 fs/read_write.c:1567
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c4a9
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:00007f8c20e5dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f8c20e5e6d4 RCX: 000000000045c4a9
RDX: 00000000200001c0 RSI: 0000000000000006 RDI: 0000000000000006
RBP: 000000000076c1a0 R08: 0000000000000000 R09: 0000000000000000
R10: 00008080fffffffe R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008d1 R14: 00000000004cb3b0 R15: 000000000076c1ac