rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P13600/1:b..l
	(detected by 1, t=10503 jiffies, g=60805, q=220)
task:udevd           state:R  running task     stack:25184 pid:13600 ppid:  3547 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6552
 preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6577
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
 _raw_spin_unlock_irq+0x3c/0x40 kernel/locking/spinlock.c:202
 spin_unlock_irq include/linux/spinlock.h:413 [inline]
 loop_queue_work drivers/block/loop.c:1069 [inline]
 loop_queue_rq+0x9e0/0xac0 drivers/block/loop.c:2202
 __blk_mq_issue_directly block/blk-mq.c:2014 [inline]
 __blk_mq_try_issue_directly+0x497/0x810 block/blk-mq.c:2070
 blk_mq_try_issue_directly+0xaf/0x270 block/blk-mq.c:2101
 blk_mq_submit_bio+0xf17/0x17b0 block/blk-mq.c:-1
 __submit_bio+0x7bd/0x810 block/blk-core.c:917
 __submit_bio_noacct_mq block/blk-core.c:997 [inline]
 submit_bio_noacct+0x5f1/0x6d0 block/blk-core.c:1027
 submit_bio+0x2be/0x560 block/blk-core.c:1089
 submit_bh fs/buffer.c:3062 [inline]
 block_read_full_page+0x8eb/0xd10 fs/buffer.c:2341
 filemap_read_page+0x17b/0x4c0 mm/filemap.c:2386
 filemap_update_page mm/filemap.c:2464 [inline]
 filemap_get_pages mm/filemap.c:2574 [inline]
 filemap_read+0x13d5/0x2480 mm/filemap.c:2634
 blkdev_read_iter+0x11d/0x150 block/fops.c:563
 call_read_iter include/linux/fs.h:2166 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x725/0xcf0 fs/read_write.c:485
 ksys_read+0x14d/0x250 fs/read_write.c:623
 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: 0033:0x7fbbb77bb407
RSP: 002b:00007fff4a60f650 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fbbb76cd880 RCX: 00007fbbb77bb407
RDX: 0000000000000200 RSI: 00007fbbb6d83000 RDI: 0000000000000009
RBP: 00005601e5752000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000000000 R14: 00005601e575f748 R15: 00007fbbb7f1139c
 </TASK>
rcu: rcu_preempt kthread starved for 10460 jiffies! g60805 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:27584 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 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:722