rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4586/1:b..l
	(detected by 0, t=10502 jiffies, g=9209, q=518)
task:syz.2.82        state:R  running task     stack:24392 pid: 4586 ppid:  4171 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6780
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:35 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:106 [inline]
RIP: 0010:lock_is_held_type+0x64/0x190 kernel/locking/lockdep.c:5662
Code: 00 00 00 65 48 8b 1d 0b 40 61 76 83 bb ec 0a 00 00 00 0f 85 df 00 00 00 41 89 f7 49 89 fe 48 c7 04 24 00 00 00 00 9c 8f 04 24 <4c> 8b 2c 24 fa 48 c7 c7 c0 1d 0b 8a e8 4b 0e 00 00 65 ff 05 14 49
RSP: 0018:ffffc9000122f278 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff88802bc81dc0 RCX: 778c0706294bbf00
RDX: 0000000000000002 RSI: 00000000ffffffff RDI: ffffffff8c11bf20
RBP: 00000000ffffffff R08: dffffc0000000000 R09: fffffbfff1ff3219
R10: fffffbfff1ff3219 R11: 1ffffffff1ff3218 R12: dffffc0000000000
R13: 1ffff1100c8388c9 R14: ffffffff8c11bf20 R15: 00000000ffffffff
 lock_is_held include/linux/lockdep.h:287 [inline]
 rcu_read_lock_sched_held+0x86/0xf0 kernel/rcu/update.c:125
 task_css include/linux/cgroup.h:496 [inline]
 blkcg_css include/linux/blk-cgroup.h:231 [inline]
 bio_associate_blkg+0x154/0x340 block/blk-cgroup.c:1902
 submit_bh_wbc+0x339/0x670 fs/buffer.c:3033
 submit_bh+0x23/0x30 fs/buffer.c:3062
 ext4_sb_breadahead_unmovable+0xc2/0xe0 fs/ext4/super.c:243
 __ext4_get_inode_loc+0x97b/0xcd0 fs/ext4/inode.c:4404
 ext4_get_inode_loc fs/ext4/inode.c:4450 [inline]
 ext4_reserve_inode_write+0x140/0x2e0 fs/ext4/inode.c:5825
 __ext4_mark_inode_dirty+0x142/0x700 fs/ext4/inode.c:6002
 __ext4_new_inode+0x2fab/0x39e0 fs/ext4/ialloc.c:1342
 ext4_create+0x22a/0x460 fs/ext4/namei.c:2883
 lookup_open fs/namei.c:3462 [inline]
 open_last_lookups fs/namei.c:3532 [inline]
 path_openat+0x11e1/0x2f30 fs/namei.c:3739
 do_filp_open+0x1b3/0x3e0 fs/namei.c:3769
 do_sys_openat2+0x142/0x4a0 fs/open.c:1253
 do_sys_open fs/open.c:1269 [inline]
 __do_sys_openat fs/open.c:1285 [inline]
 __se_sys_openat fs/open.c:1280 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1280
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f9a17d7f969
RSP: 002b:00007f9a15be7038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f9a17fa6fa0 RCX: 00007f9a17d7f969
RDX: 000000000000275a RSI: 00002000000001c0 RDI: ffffffffffffff9c
RBP: 00007f9a17e01ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f9a17fa6fa0 R15: 00007ffe632dfc18
 </TASK>
rcu: rcu_preempt kthread starved for 10095 jiffies! g9209 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:27464 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:722