rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (1 GPs behind) idle=f16/1/0x4000000000000002 softirq=25161/25166 fqs=0 
	(t=10500 jiffies g=25061 q=52)
rcu: rcu_preempt kthread starved for 10500 jiffies! g25061 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    28952    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3386 [inline]
 __schedule+0x87f/0xcd0 kernel/sched/core.c:4082
 schedule+0x188/0x210 kernel/sched/core.c:4156
 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1658 [inline]
 rcu_gp_kthread+0xe8d/0x17e0 kernel/rcu/tree.c:1818
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 0
CPU: 0 PID: 13464 Comm: syz-executor.0 Not tainted 5.6.0-rc1-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+0x1fb/0x318 lib/dump_stack.c:118
 nmi_cpu_backtrace+0xaa/0x190 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x16f/0x290 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x15a/0x220 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+0x1521/0x1aa0 kernel/rcu/tree.c:2276
 update_process_times+0x12d/0x180 kernel/time/timer.c:1726
 tick_sched_handle kernel/time/tick-sched.c:171 [inline]
 tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1314
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x3f3/0x840 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x37c/0xda0 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline]
 smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1144
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:cpu_max_bits_warn include/linux/cpumask.h:137 [inline]
RIP: 0010:cpumask_check include/linux/cpumask.h:144 [inline]
RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:360 [inline]
RIP: 0010:trace_ext4_journal_start+0x185/0x2f0 include/trace/events/ext4.h:1764
Code: f6 65 ff 0d 49 61 04 7e 0f 94 c3 40 0f 94 c6 31 ff e8 7f 45 79 ff 84 db 0f 85 5a 01 00 00 e8 e2 42 79 ff 65 8b 1d a3 f6 03 7e <bf> 3f 00 00 00 89 de e8 7f 46 79 ff 83 fb 3f 0f 87 15 01 00 00 e8
RSP: 0018:ffffc900032774a0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffffff81fdbb50 RBX: 0000000000000000 RCX: 0000000000040000
RDX: ffffc90006462000 RSI: 000000000003ffff RDI: 0000000000040000
RBP: ffffc900032774d8 R08: ffffffff82057ebe R09: 0000000000000008
R10: ffffed1015d47004 R11: 0000000000000000 R12: 0000000000000002
R13: 0000000000000002 R14: ffff8880995de000 R15: ffff8880995de000
 __ext4_journal_start_sb+0x3e/0x170 fs/ext4/ext4_jbd2.c:97
 __ext4_journal_start fs/ext4/ext4_jbd2.h:325 [inline]
 ext4_dirty_inode+0xae/0x110 fs/ext4/inode.c:5798
 __mark_inode_dirty+0xbf/0x720 fs/fs-writeback.c:2258
 mark_inode_dirty include/linux/fs.h:2183 [inline]
 generic_write_end+0x302/0x440 fs/buffer.c:2199
 ext4_da_write_end+0x784/0x900 fs/ext4/inode.c:3092
 generic_perform_write+0x341/0x4f0 mm/filemap.c:3298
 ext4_buffered_write_iter+0x443/0x5c0 fs/ext4/file.c:270
 ext4_file_write_iter+0xb06/0x1810 include/linux/fs.h:796
 do_iter_readv_writev+0x651/0x8e0 include/linux/fs.h:1895
 do_iter_write+0x180/0x590 fs/read_write.c:998
 vfs_iter_write+0x7c/0xa0 fs/read_write.c:1039
 iter_file_splice_write+0x6cb/0xe40 fs/splice.c:760
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0xf7/0x130 fs/splice.c:1037
 splice_direct_to_actor+0x4c2/0xb90 fs/splice.c:992
 do_splice_direct+0x200/0x330 fs/splice.c:1080
 do_sendfile+0x7e4/0xfd0 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+0xfc/0x1b0 fs/read_write.c:1567
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45b3b9
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:00007f71e1d05c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f71e1d066d4 RCX: 000000000045b3b9
RDX: 00000000200001c0 RSI: 0000000000000006 RDI: 0000000000000006
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 00008080fffffffe R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008cb R14: 00000000004ca26f R15: 000000000075bfd4