rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (10499 ticks this GP) idle=862/1/0x4000000000000002 softirq=106470/106470 fqs=4582 
rcu: 	 (t=10500 jiffies g=168933 q=3046)
NMI backtrace for cpu 1
CPU: 1 PID: 6893 Comm: syz-executor0 Not tainted 5.0.0-rc1-next-20190108 #7
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+0x1db/0x2d0 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1be/0x236 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.c:1211
 print_cpu_stall.cold+0x227/0x40c kernel/rcu/tree.c:1348
 check_cpu_stall kernel/rcu/tree.c:1422 [inline]
 rcu_pending kernel/rcu/tree.c:3018 [inline]
 rcu_check_callbacks+0xb32/0x1380 kernel/rcu/tree.c:2521
 update_process_times+0x32/0x80 kernel/time/timer.c:1635
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:161
 tick_sched_timer+0x47/0x130 kernel/time/tick-sched.c:1271
 __run_hrtimer kernel/time/hrtimer.c:1389 [inline]
 __hrtimer_run_queues+0x3a7/0x1050 kernel/time/hrtimer.c:1451
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1035 [inline]
 smp_apic_timer_interrupt+0x18d/0x760 arch/x86/kernel/apic/apic.c:1060
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
 </IRQ>
RIP: 0010:__sanitizer_cov_trace_pc+0x2b/0x50 kernel/kcov.c:104
Code: 48 89 e5 48 8b 75 08 65 48 8b 04 25 40 ee 01 00 65 8b 15 28 d5 7f 7e 81 e2 00 01 1f 00 75 2b 8b 90 e0 12 00 00 83 fa 02 75 20 <48> 8b 88 e8 12 00 00 8b 80 e4 12 00 00 48 8b 11 48 83 c2 01 48 39
RSP: 0018:ffff8880478d6ac8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffff888052126680 RBX: ffff8880478d6bc0 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff87f197f9 RDI: ffff8880478d6bc0
RBP: ffff8880478d6ac8 R08: ffff888052126680 R09: ffffed1015ce5b90
R10: ffffed1015ce5b8f R11: ffff8880ae72dc7b R12: 1ffff11008f1ad7b
R13: ffff8880478d6d40 R14: dffffc0000000000 R15: dffffc0000000000
 xas_load+0x19/0x160 lib/xarray.c:227
 find_get_entry+0x353/0x1090 mm/filemap.c:1476
 pagecache_get_page+0xe5/0x1070 mm/filemap.c:1582
 find_get_page_flags include/linux/pagemap.h:279 [inline]
 __find_get_block_slow fs/buffer.c:205 [inline]
 __find_get_block fs/buffer.c:1331 [inline]
 __find_get_block+0x615/0xf20 fs/buffer.c:1325
 __getblk_slow fs/buffer.c:1058 [inline]
 __getblk_gfp+0x3c2/0x1140 fs/buffer.c:1357
 __bread_gfp+0x2f/0x300 fs/buffer.c:1391
 sb_bread include/linux/buffer_head.h:307 [inline]
 fat_ent_bread+0x16c/0x290 fs/fat/fatent.c:107
 fat_ent_read+0x646/0xc30 fs/fat/fatent.c:366
 fat_free_clusters+0x31c/0xeb0 fs/fat/fatent.c:563
 fat_free fs/fat/file.c:379 [inline]
 fat_truncate_blocks+0x9a1/0x1160 fs/fat/file.c:397
 fat_setattr+0xc3c/0xe20 fs/fat/file.c:541
 notify_change+0xb8d/0x1080 fs/attr.c:334
 do_truncate+0x1ba/0x2d0 fs/open.c:63
 handle_truncate fs/namei.c:3008 [inline]
 do_last fs/namei.c:3424 [inline]
 path_openat+0x3812/0x5660 fs/namei.c:3534
 do_filp_open+0x26f/0x370 fs/namei.c:3564
 do_sys_open+0x59a/0x7c0 fs/open.c:1063
 ksys_open include/linux/syscalls.h:1298 [inline]
 __do_sys_creat fs/open.c:1121 [inline]
 __se_sys_creat fs/open.c:1119 [inline]
 __x64_sys_creat+0x61/0x80 fs/open.c:1119
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457ec9
Code: 6d 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 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f05f5f9cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 0000000000457ec9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f05f5f9d6d4
R13: 00000000004be42a R14: 00000000004ce8b8 R15: 00000000ffffffff