GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=505873, q=721 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4295240540-4295230038), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g505873 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x200
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=216221
rcu: rcu_preempt kthread starved for 10502 jiffies! g505873 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x200 ->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 stack:27536 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 __schedule+0x1821/0x5740
 schedule+0x164/0x360
 schedule_timeout+0x158/0x2c0
 rcu_gp_fqs_loop+0x312/0x11d0
 rcu_gp_kthread+0x9e/0x2b0
 kthread+0x389/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 23191 Comm: udevd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:mark_lock+0x95/0x190
Code: 83 3d 32 1a 8f 0e 00 75 13 48 8d 3d c5 4a 92 0e 48 c7 c6 fb 9a 0c 8e 67 48 0f b9 3a 90 31 c9 4c 89 fe 4c 89 f7 b8 01 00 00 00 <85> 69 60 74 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 17 64 0a 0a cc 49
RSP: 0018:ffffc90000a08970 EFLAGS: 00000006
RAX: 0000000000000001 RBX: 0000000000000004 RCX: ffffffff93e26370
RDX: 0000000000000004 RSI: ffff888109906488 RDI: ffff888109905880
RBP: 0000000000000010 R08: ffffffff84bcdf03 R09: ffffffff9a6fd180
R10: dffffc0000000000 R11: fffff52000141178 R12: 0000000000000002
R13: ffff888109906488 R14: ffff888109905880 R15: 0000000000000003
FS:  00007f8a1437ac80(0000) GS:ffff8882a9287000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c245ab9 CR3: 0000000112168000 CR4: 00000000000006f0
DR0: 0000000000000004 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 __lock_acquire+0x689/0x2cf0
 lock_acquire+0x106/0x350
 _raw_spin_lock_irqsave+0x40/0x60
 debug_object_activate+0x83/0x580
 enqueue_hrtimer+0xa9/0x2c0
 __hrtimer_run_queues+0x4d2/0xa20
 hrtimer_interrupt+0x44b/0x950
 __sysvec_apic_timer_interrupt+0x102/0x430
 sysvec_apic_timer_interrupt+0x52/0xc0
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:handle_softirqs+0x160/0x840
Code: 89 6c 24 20 0f b7 db 48 c7 c7 20 1d cb 8b e8 e7 b0 21 0a 65 66 c7 05 55 bf b1 11 00 00 e8 a8 12 46 00 fb 48 c7 c5 c0 a0 60 8e <b8> ff ff ff ff 0f bc c3 41 89 c6 41 ff c6 0f 84 09 04 00 00 89 5c
RSP: 0018:ffffc90000a08f28 EFLAGS: 00000202
RAX: 00000000003c1f1a RBX: 0000000000000004 RCX: 0000000080000100
RDX: 0000000000000003 RSI: ffffffff8dfad305 RDI: ffffffff8c28b860
RBP: ffffffff8e60a0c0 R08: ffffffff9030dbf7 R09: 1ffffffff2061b7e
R10: dffffc0000000000 R11: fffffbfff2061b7f R12: 0000000000000000
R13: 0000000000000000 R14: ffff888109905880 R15: dffffc0000000000
 __irq_exit_rcu+0xca/0x220
 irq_exit_rcu+0x9/0x30
 sysvec_apic_timer_interrupt+0xa6/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:blk_cgroup_congested+0xf9/0x210
Code: fc ff df 4d 8d be 64 01 00 00 4c 89 ff be 04 00 00 00 e8 5a 00 97 fd 4c 89 f8 48 c1 e8 03 42 0f b6 04 20 84 c0 75 40 41 8b 2f <31> ff 89 ee e8 3e bd 2b fd 85 ed 40 0f 95 c5 75 4c 49 81 c6 08 01
RSP: 0018:ffffc90007967670 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffffff8499fc1d RCX: ffffffff8499fce6
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff9a638824
RBP: 0000000000000000 R08: ffffffff9a638827 R09: 1ffffffff34c7104
R10: dffffc0000000000 R11: fffffbfff34c7105 R12: dffffc0000000000
R13: 1ffff92000f2cf1e R14: ffffffff9a6386c0 R15: ffffffff9a638824
 page_cache_sync_ra+0x1e8/0xa90
 filemap_get_pages+0x4c0/0x1ef0
 filemap_read+0x447/0x1230
 blkdev_read_iter+0x30a/0x440
 vfs_read+0x582/0xa70
 ksys_read+0x150/0x270
 do_syscall_64+0x15f/0x560
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8a13f16b6a
Code: 00 3d 00 00 41 00 75 0d 50 48 8d 3d 2d 08 0a 00 e8 ea 7d 01 00 31 c0 e9 07 ff ff ff 64 8b 04 25 18 00 00 00 85 c0 75 1b 0f 05 <48> 3d 00 f0 ff ff 76 6c 48 8b 15 8f a2 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffc33183868 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000003c00 RCX: 00007f8a13f16b6a
RDX: 0000000000000400 RSI: 00005638a22240b8 RDI: 0000000000000009
RBP: 0000000000000400 R08: 00005638a2224090 R09: 0000000000000001
R10: 0000000000000051 R11: 0000000000000246 R12: 00005638a2224090
R13: 00005638a22240a8 R14: 00005638a2214b68 R15: 00005638a2214b10
 </TASK>
