rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P1087/1:b..l P17688/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=38429, q=1776 ncpus=2)
task:syz.3.1068      state:R  running task     stack:26272 pid:17688 tgid:17687 ppid:16189  task_flags:0x40054c flags:0x00004000
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 preempt_schedule_common+0x83/0xd0
 preempt_schedule+0xae/0xc0
 preempt_schedule_thunk+0x16/0x30
 _raw_spin_unlock+0x3f/0x50
 unmap_page_range+0x3a79/0x4370
 unmap_vmas+0x399/0x580
 exit_mmap+0x248/0xb50
 __mmput+0x118/0x420
 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: 0033:0x7fb8b8b8ebe9
RSP: 002b:00007fb8b99e30e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fb8b8db5fa8 RCX: 00007fb8b8b8ebe9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fb8b8db5fa8
RBP: 00007fb8b8db5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb8b8db6038 R14: 00007ffe69108b30 R15: 00007ffe69108c18
 </TASK>
task:kworker/u9:4    state:R  running task     stack:21480 pid:1087  tgid:1087  ppid:2      task_flags:0x4208060 flags:0x00004000
Workqueue: iou_exit io_ring_exit_work
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 preempt_schedule_irq+0xb5/0x150
 irqentry_exit+0x6f/0x90
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:unwind_next_frame+0xabc/0x2390
Code: 76 01 83 e6 07 83 fe 04 4c 89 64 24 10 0f 84 49 04 00 00 83 fe 03 0f 84 f3 01 00 00 83 fe 02 0f 85 a1 07 00 00 4c 89 7c 24 28 <4d> 8d 7e 08 4c 89 fd 48 c1 ed 03 48 b8 00 00 00 00 00 fc ff df 80
RSP: 0018:ffffc90006a470d8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffffff902d9559 RCX: ffffffff8fb3890c
RDX: ffffffff902d9554 RSI: 0000000000000002 RDI: ffffffff8be33620
RBP: dffffc0000000000 R08: 0000000000000011 R09: 0000000000000000
R10: ffffc90006a471f8 R11: ffffffff81ac3810 R12: ffffc90006a478e0
R13: ffffc90006a471f8 R14: ffffc90006a471a8 R15: 1ffffffff205b2ab
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 kasan_save_track+0x3e/0x80
 __kasan_slab_alloc+0x6c/0x80
 kmem_cache_alloc_noprof+0x1c1/0x3c0
 fill_pool+0x100/0x570
 debug_object_activate+0x383/0x420
 call_rcu+0xaa/0x9c0
 kmem_cache_free+0x309/0x400
 __io_req_caches_free+0x8f/0x140
 io_req_caches_free+0x21/0x60
 io_ring_exit_work+0x415/0x930
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g38429 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=14839
rcu: rcu_preempt kthread starved for 10502 jiffies! g38429 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:
task:rcu_preempt     state:I stack:26920 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+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 5869 Comm: kworker/u8:3 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
Workqueue: bat_events batadv_nc_worker
RIP: 0010:__netif_schedule+0x90/0x2c0
Code: df 49 89 44 0d 00 66 41 c7 44 0d 09 f3 f3 41 c6 44 0d 0b f3 e8 31 d0 5d f8 48 8d bb 58 01 00 00 be 08 00 00 00 e8 10 3c c1 f8 <31> f6 f0 48 0f ba ab 58 01 00 00 00 41 0f 93 c6 40 0f 92 c6 bf 02
RSP: 0018:ffffc90000007b80 EFLAGS: 00000056
RAX: ffffffff8961da01 RBX: ffff8880339ff000 RCX: ffffffff8961db10
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff8880339ff158
RBP: ffffc90000007c60 R08: ffff8880339ff15f R09: 1ffff1100673fe2b
R10: dffffc0000000000 R11: ffffed100673fe2c R12: ffff8880339ff360
R13: 1ffff92000000f74 R14: 1874e65604000000 R15: ffff88803499f800
FS:  0000000000000000(0000) GS:ffff8880b861b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2eb63fff CR3: 0000000106dba000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 advance_sched+0xa9a/0xc90
 __hrtimer_run_queues+0x52c/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:__sanitizer_cov_trace_pc+0x8/0x70
Code: 8b 3d c4 49 fe 0b 48 89 de 5b e9 73 98 58 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0c 25 08 50 a0 92 65 8b 15 e8 a4 e0 10 81 e2 00 01 ff 00
RSP: 0018:ffffc9000327fa18 EFLAGS: 00000202
RAX: ffffffff8b4704e0 RBX: 0000000000000000 RCX: ffff88801ef59c01
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: fffffffffffffe38 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff8b470340 R12: dffffc0000000000
R13: ffffffff8b470412 R14: ffff888035f88d80 R15: 000000000000020c
 batadv_nc_worker+0x1a0/0x610
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
