rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (1 GPs behind) idle=2ce/1/0x4000000000000002 softirq=32524/32525 fqs=17 
	(t=10501 jiffies g=49393 q=264)
rcu: rcu_preempt kthread starved for 10466 jiffies! g49393 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29520    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3252 [inline]
 __schedule+0x755/0x1580 kernel/sched/core.c:3878
 schedule+0xa8/0x270 kernel/sched/core.c:3942
 schedule_timeout+0x486/0xc50 kernel/time/timer.c:1807
 rcu_gp_fqs_loop kernel/rcu/tree.c:1611 [inline]
 rcu_gp_kthread+0x9b2/0x18c0 kernel/rcu/tree.c:1768
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:353
NMI backtrace for cpu 0
CPU: 0 PID: 18403 Comm: syz-executor.2 Not tainted 5.2.0-rc7-next-20190701 #26
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+0x172/0x1f0 lib/dump_stack.c:113
 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+0x183/0x1cf 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:2736 [inline]
 rcu_sched_clock_irq.cold+0x4dd/0xc13 kernel/rcu/tree.c:2183
 update_process_times+0x32/0x80 kernel/time/timer.c:1639
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167
 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1296
 __run_hrtimer kernel/time/hrtimer.c:1389 [inline]
 __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1451
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1068 [inline]
 smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1093
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
 </IRQ>
RIP: 0010:xa_is_value include/linux/xarray.h:79 [inline]
RIP: 0010:pagecache_get_page+0x4e/0x880 mm/filemap.c:1609
Code: cd 41 54 53 89 d3 48 83 ec 28 48 89 7d d0 48 89 75 c8 48 89 45 b8 e8 01 a8 e3 ff 48 8b 75 c8 48 8b 7d d0 e8 24 5b ff ff 31 ff <41> 89 c7 49 89 c4 41 83 e7 01 44 89 fe e8 20 a9 e3 ff 45 84 ff 0f
RSP: 0018:ffff88805584f850 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffea0001c45300 RBX: 0000000000000000 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 1ffff110110311b8 RDI: 0000000000000000
RBP: ffff88805584f8a0 R08: 0000000000000002 R09: ffff888088188d90
R10: fffffbfff134699f R11: ffffffff89a34cff R12: 000000000000ffff
R13: 0000000000000000 R14: dffffc0000000000 R15: dffffc0000000000
 find_get_page include/linux/pagemap.h:260 [inline]
 generic_file_buffered_read mm/filemap.c:2020 [inline]
 generic_file_read_iter+0x5ef/0x1ce0 mm/filemap.c:2297
 ext4_file_read_iter fs/ext4/file.c:77 [inline]
 ext4_file_read_iter+0x1d6/0x420 fs/ext4/file.c:65
 call_read_iter include/linux/fs.h:1864 [inline]
 generic_file_splice_read+0x4af/0x800 fs/splice.c:307
 do_splice_to+0x127/0x180 fs/splice.c:877
 splice_direct_to_actor+0x2d2/0x970 fs/splice.c:954
 do_splice_direct+0x1da/0x2a0 fs/splice.c:1063
 do_sendfile+0x597/0xd00 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1525 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459519
Code: fd 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f4d94074c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000459519
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 00008000fffffffe R11: 0000000000000246 R12: 00007f4d940756d4
R13: 00000000004c6af0 R14: 00000000004dbd68 R15: 00000000ffffffff