GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (2 ticks this GP) idle=dec4/1/0x4000000000000000 softirq=69275/69275 fqs=1
rcu: 	(detected by 0, t=10505 jiffies, g=43841, q=1876 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5848 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:lock_release+0xaa/0x3e0
Code: 92 41 83 bf ec 0a 00 00 00 0f 85 1e 02 00 00 49 81 3e 20 93 64 93 0f 84 11 02 00 00 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 <48> 8b 5c 24 20 fa 48 c7 c7 b1 dc 9c 8d e8 64 b3 dd 09 65 ff 05 0d
RSP: 0018:ffffc900001e0b78 EFLAGS: 00000002
RAX: 0000000000000000 RBX: 0000000000000802 RCX: 9156599a85b11600
RDX: 0000000000000001 RSI: ffffffff8be33ee0 RDI: ffffffff8be33ea0
RBP: ffffc900001e0c78 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200003c16c R12: dffffc0000000000
R13: ffffffff84d0b6b2 R14: ffffffff99cdb4b8 R15: ffff88802051d640
FS:  0000000000000000(0000) GS:ffff8881a3c13000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5f5c2e3990 CR3: 000000000df36000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 _raw_spin_unlock_irqrestore+0x70/0x110
 debug_object_activate+0x2e2/0x420
 enqueue_hrtimer+0x30/0x3a0
 __hrtimer_run_queues+0x656/0xc60
 hrtimer_interrupt+0x45b/0xaa0
 __sysvec_apic_timer_interrupt+0x10b/0x410
 sysvec_apic_timer_interrupt+0xa1/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:rcu_is_watching+0x10/0xb0
Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 57 41 56 53 65 ff 05 30 70 fa 10 <e8> 1b c1 d4 09 89 c3 83 f8 08 73 65 49 bf 00 00 00 00 00 fc ff df
RSP: 0018:ffffc9000372f2e8 EFLAGS: 00000282
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffff88802051d640
RDX: 0000000000000000 RSI: 0000000000001000 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff822e5c37
R10: dffffc0000000000 R11: fffff940008c70d1 R12: 0000000000118e1a
R13: dffffc0000000000 R14: ffff88805fffa870 R15: 0000000000001000
 rcu_read_lock_held+0x15/0x50
 page_ext_lookup+0xe7/0x180
 page_table_check_clear+0x278/0x700
 unmap_page_range+0x3445/0x4370
 unmap_vmas+0x399/0x580
 exit_mmap+0x248/0xb50
 __mmput+0x118/0x430
 exit_mm+0x1da/0x2c0
 do_exit+0x648/0x2300
 do_group_exit+0x21c/0x2d0
 get_signal+0x1286/0x1340
 arch_do_signal_or_restart+0x9a/0x750
 exit_to_user_mode_loop+0x75/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7f00b84e53
Code: Unable to access opcode bytes at 0x7f7f00b84e29.
RSP: 002b:00007ffefcec2aa8 EFLAGS: 00000202 ORIG_RAX: 000000000000003d
RAX: fffffffffffffe00 RBX: 00000000000016de RCX: 00007f7f00b84e53
RDX: 0000000040000000 RSI: 00007ffefcec2abc RDI: 00000000ffffffff
RBP: 00007ffefcec2abc R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008
R13: 0000000000000003 R14: 0000000000000009 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 6858 jiffies! g43841 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:27160 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_timeout+0x12b/0x270
 rcu_gp_fqs_loop+0x301/0x1540
 rcu_gp_kthread+0x99/0x390
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 5594 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:smp_call_function_many_cond+0xd33/0x12d0
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 86 63 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 31 5f 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 15 5f
RSP: 0018:ffffc90002e6f540 EFLAGS: 00000293
RAX: ffffffff81b44e7b RBX: 1ffff11026cc7f69 RCX: ffff888020bf9cc0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90002e6f6c0 R08: ffffffff8fa38f37 R09: 1ffffffff1f471e6
R10: dffffc0000000000 R11: fffffbfff1f471e7 R12: ffff88813663fb48
R13: dffffc0000000000 R14: ffff88804b03b1c0 R15: 0000000000000001
FS:  00007f7bdf452740(0000) GS:ffff8880b8613000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7bdf5fe580 CR3: 00000000280d8000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80
 flush_tlb_mm_range+0x6b1/0x12d0
 dup_mmap+0x15a0/0x1ac0
 copy_mm+0x13c/0x4b0
 copy_process+0x1706/0x3c00
 kernel_clone+0x21e/0x840
 __x64_sys_clone+0x18b/0x1e0
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7bdf502a12
Code: 41 5d 41 5e 41 5f c3 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 10 48 8b 15 e7 43 0f 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffeb7fbbc08 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000564cd272ec01 RCX: 00007f7bdf502a12
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffeb7fdc178 R08: 0000000000000000 R09: 0000564cd272ec90
R10: 00007f7bdf452a10 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000564cd272ecc4
 </TASK>
