rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10500 ticks this GP) idle=1aa/1/0x4000000000000000 softirq=110910/110910 fqs=0 
	(t=10500 jiffies g=216613 q=8224)
rcu: rcu_preempt kthread starved for 10500 jiffies! g216613 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
rcu_preempt     I28984    10      2 0x00004000
Call Trace:
 context_switch kernel/sched/core.c:3430 [inline]
 __schedule+0x8e1/0x1eb0 kernel/sched/core.c:4155
 schedule+0xd0/0x2a0 kernel/sched/core.c:4230
 schedule_timeout+0x148/0x250 kernel/time/timer.c:1897
 rcu_gp_fqs_loop kernel/rcu/tree.c:1856 [inline]
 rcu_gp_kthread+0xae5/0x1b50 kernel/rcu/tree.c:2026
 kthread+0x3b5/0x4a0 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
NMI backtrace for cpu 0
CPU: 0 PID: 10548 Comm: syz-executor.1 Not tainted 5.8.0-rc2-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+0x18f/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x194/0x1cf kernel/rcu/tree_stall.h:320
 print_cpu_stall kernel/rcu/tree_stall.h:553 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:627 [inline]
 rcu_pending kernel/rcu/tree.c:3471 [inline]
 rcu_sched_clock_irq.cold+0x5b3/0xccc kernel/rcu/tree.c:2486
 update_process_times+0x25/0x60 kernel/time/timer.c:1726
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176
 tick_sched_timer+0x108/0x290 kernel/time/tick-sched.c:1320
 __run_hrtimer kernel/time/hrtimer.c:1520 [inline]
 __hrtimer_run_queues+0x1d5/0xfc0 kernel/time/hrtimer.c:1584
 hrtimer_interrupt+0x32a/0x930 kernel/time/hrtimer.c:1646
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline]
 __sysvec_apic_timer_interrupt+0x142/0x5e0 arch/x86/kernel/apic/apic.c:1097
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 sysvec_apic_timer_interrupt+0x18f/0x220 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:596
RIP: 0010:debug_lockdep_rcu_enabled+0x76/0xe0 kernel/rcu/update.c:290
Code: c1 83 e0 07 48 c1 e9 03 83 c0 03 0f b6 14 11 38 d0 7c 04 84 d2 75 64 8b 0d 4b a9 c9 02 85 c9 74 45 65 48 8b 1c 25 00 ff 01 00 <48> 8d bb cc 08 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1
RSP: 0018:ffffc9001eacf2b0 EFLAGS: 00000202
RAX: 0000000000000007 RBX: ffff8881fa31c080 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000005
RBP: ffff88809fd55040 R08: 0000000000000000 R09: ffff8880ae636cdb
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888214f94800
R13: 0000000000000000 R14: ffff888214426668 R15: ffff888215298000
 rcu_read_unlock include/linux/rcupdate.h:684 [inline]
 ext4_get_group_info+0x1b5/0x3a0 fs/ext4/ext4.h:3048
 ext4_validate_block_bitmap+0x2c/0xb90 fs/ext4/balloc.c:371
 ext4_read_block_bitmap_nowait+0xd04/0x1f80 fs/ext4/balloc.c:496
 ext4_read_block_bitmap+0x1b/0xa0 fs/ext4/balloc.c:537
 ext4_free_blocks+0x565/0x23c0 fs/ext4/mballoc.c:4996
 ext4_remove_blocks fs/ext4/extents.c:2503 [inline]
 ext4_ext_rm_leaf fs/ext4/extents.c:2669 [inline]
 ext4_ext_remove_space+0x1fd7/0x4420 fs/ext4/extents.c:2917
 ext4_ext_truncate+0x1dc/0x240 fs/ext4/extents.c:4377
 ext4_truncate+0xee0/0x14b0 fs/ext4/inode.c:4217
 ext4_evict_inode+0xa15/0x11e0 fs/ext4/inode.c:280
 evict+0x2ed/0x750 fs/inode.c:576
 iput_final fs/inode.c:1652 [inline]
 iput.part.0+0x424/0x850 fs/inode.c:1678
 iput+0x58/0x70 fs/inode.c:1668
 dentry_unlink_inode+0x2b1/0x3d0 fs/dcache.c:374
 __dentry_kill+0x3c0/0x640 fs/dcache.c:579
 dentry_kill fs/dcache.c:717 [inline]
 dput+0x635/0xbc0 fs/dcache.c:878
 path_put+0x2d/0x60 fs/namei.c:496
 free_fs_struct fs/fs_struct.c:91 [inline]
 exit_fs+0xf9/0x170 fs/fs_struct.c:108
 do_exit+0xb4a/0x2a40 kernel/exit.c:801
 do_group_exit+0x125/0x310 kernel/exit.c:903
 get_signal+0x428/0x1fc0 kernel/signal.c:2739
 do_signal+0x82/0x2520 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop arch/x86/entry/common.c:212 [inline]
 __prepare_exit_to_usermode+0x156/0x1f0 arch/x86/entry/common.c:246
 do_syscall_64+0x6c/0xe0 arch/x86/entry/common.c:368
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cb19
Code: Bad RIP value.
RSP: 002b:00007f7889a75cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000078bf08 RCX: 000000000045cb19
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000078bf08
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007ffe7cd519cf R14: 00007f7889a769c0 R15: 000000000078bf0c