rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=8964/1/0x4000000000000000 softirq=0/0 fqs=37 rcuc=10502 jiffies(starved)
rcu: 	(t=10500 jiffies g=121957 q=1905 ncpus=2)
rcu: rcu_preempt kthread timer wakeup didn't happen for 10413 jiffies! g121957 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=70611
rcu: rcu_preempt kthread starved for 10414 jiffies! g121957 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:27736 pid:18    tgid:18    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 __schedule+0x16f9/0x5500
 schedule+0x164/0x360
 schedule_timeout+0x158/0x2c0
 rcu_gp_fqs_loop+0x312/0x11b0
 rcu_gp_kthread+0x9e/0x2b0
 kthread+0x388/0x470
 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(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:pv_native_safe_halt+0xf/0x20
Code: 6b 64 02 e9 83 cc 03 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d 43 eb 20 00 fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffffff8dc07dc0 EFLAGS: 00000206
RAX: 00000000003f5f6f RBX: ffffffff81997aaa RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8d626ff0 RDI: ffffffff8ba85b60
RBP: ffffffff8dc07eb0 R08: ffff888121033d1b R09: 1ffff110242067a3
R10: dffffc0000000000 R11: ffffed10242067a4 R12: 0000000000000000
R13: 1ffffffff1b9fdd8 R14: 0000000000000000 R15: 1ffffffff1b9fdd8
FS:  0000000000000000(0000) GS:ffff88818e91f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe62be1000 CR3: 0000000170eee000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 default_idle+0x9/0x20
 default_idle_call+0x72/0xb0
 do_idle+0x36a/0x5f0
 cpu_startup_entry+0x43/0x60
 rest_init+0x2de/0x300
 start_kernel+0x38a/0x3e0
 x86_64_start_reservations+0x24/0x30
 x86_64_start_kernel+0x143/0x1c0
 common_startup_64+0x13e/0x157
 </TASK>
CPU: 1 UID: 0 PID: 24509 Comm: syz.4.5851 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(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:lock_acquire+0x221/0x350
Code: ff ff ff e8 f1 1d 88 09 f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 cb a8 cf 10 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 18 98 ed
RSP: 0018:ffffc90004f8f2f8 EFLAGS: 00000282
RAX: 26a26b1e05c00500 RBX: 0000000000000000 RCX: 0000000000000046
RDX: 000000004699fac5 RSI: ffffffff8d88874d RDI: ffffffff8ba85b60
RBP: ffffffff8176f286 R08: ffffffff8176f286 R09: ffffffff8dfc8240
R10: ffffc90004f8f458 R11: ffffffff81afcf20 R12: 0000000000000002
R13: ffffffff8dfc8240 R14: 0000000000000000 R15: 0000000000000246
FS:  00007fa5cf81e6c0(0000) GS:ffff8882a9f1f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b350fc000 CR3: 000000011ded8000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 unwind_next_frame+0xc3/0x2550
 arch_stack_walk+0x11b/0x150
 stack_trace_save+0xa9/0x100
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5c/0x80
 kfree+0x1c5/0x6c0
 iter_file_splice_write+0xf86/0x10f0
 direct_splice_actor+0x104/0x160
 splice_direct_to_actor+0x545/0xc80
 do_splice_direct+0x19b/0x2a0
 do_sendfile+0x547/0x7e0
 __se_sys_sendfile64+0x144/0x1a0
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa5d15ccdd9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa5cf81e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007fa5d1845fa0 RCX: 00007fa5d15ccdd9
RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000008
RBP: 00007fa5d1662d69 R08: 0000000000000000 R09: 0000000000000000
R10: 000000007fffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa5d1846038 R14: 00007fa5d1845fa0 R15: 00007fff3dc324e8
 </TASK>
