rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=64d4/1/0x4000000000000000 softirq=31821/31821 fqs=1
rcu: 	(detected by 0, t=10502 jiffies, g=26149, q=649 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 8720 Comm: syz.6.783 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:_raw_spin_unlock_irqrestore+0x98/0x110
Code: 20 f6 4c 89 f7 e8 38 19 21 f6 f7 c3 00 02 00 00 74 05 e8 cb 6b 4a f6 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 <75> 4f f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 e8 e3 10 13 f6 65
RSP: 0018:ffffc900001e0880 EFLAGS: 00000046
RAX: 1ffffffff1bf4e5b RBX: 0000000000000802 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff888136627a80
RBP: ffffc900001e0918 R08: ffff888136627a83 R09: 1ffff11026cc4f50
R10: dffffc0000000000 R11: ffffed1026cc4f51 R12: dffffc0000000000
R13: ffff888136627b00 R14: ffff888136627a80 R15: 1ffff9200003c110
FS:  00007fc91fd016c0(0000) GS:ffff8881a3c13000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5f64af1270 CR3: 000000010a712000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 hrtimer_try_to_cancel+0x3be/0x420
 hrtimer_cancel+0x3b/0x50
 cpu_clock_event_stop+0xd9/0x130
 __perf_event_overflow+0x580/0xe40
 perf_swevent_hrtimer+0x3c5/0x550
 __hrtimer_run_queues+0x4e0/0xc60
 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:do_syscall_64+0xc3/0x3b0
Code: 00 48 8b 7d 08 48 89 7b 18 e8 09 5a 00 00 0f 1f 44 00 00 0f 1f 44 00 00 90 e8 d9 5a 4d f6 90 90 e8 82 5a 4d f6 fb 49 8b 57 08 <f6> c2 3f 74 0e 4c 89 f7 4c 89 ee e8 fd 4d 30 f6 49 89 c4 90 90 41
RSP: 0018:ffffc90004417ef0 EFLAGS: 00000286
RAX: cb55e9b6e6fd3600 RBX: ffffc90004417ef0 RCX: cb55e9b6e6fd3600
RDX: 0000000000000000 RSI: ffffffff8d9ba2bf RDI: ffffffff8be33e00
RBP: ffffc90004417f48 R08: ffffffff8fa3a937 R09: 1ffffffff1f47526
R10: dffffc0000000000 R11: fffffbfff1f47527 R12: 0000000000000141
R13: 0000000000000141 R14: ffffc90004417f58 R15: ffff888035d21cc0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc91ed8eba9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc91fd01038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fc91efd5fa0 RCX: 00007fc91ed8eba9
RDX: 0000000000000090 RSI: 0000200000000800 RDI: 0000000000000005
RBP: 00007fc91ee11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc91efd6038 R14: 00007fc91efd5fa0 R15: 00007ffc714b7d28
 </TASK>
rcu: rcu_preempt kthread starved for 10495 jiffies! g26149 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: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+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 8719 Comm: rm 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:__sanitizer_cov_trace_pc+0x8/0x70
Code: 8b 3d f4 73 fe 0b 48 89 de 5b e9 13 ae 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 d0 a0 92 65 8b 15 18 0f e1 10 81 e2 00 01 ff 00
RSP: 0018:ffffc900061c7578 EFLAGS: 00000202
RAX: ffffffff81b4621b RBX: 1ffff11026cc7f61 RCX: ffff88811f19d640
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900061c7700 R08: ffffffff8fa3a937 R09: 1ffffffff1f47526
R10: dffffc0000000000 R11: fffffbfff1f47527 R12: ffff88813663fb08
R13: dffffc0000000000 R14: ffff88804b03b1c0 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b8613000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5f64af0440 CR3: 000000000df36000 CR4: 00000000000006f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 smp_call_function_many_cond+0xd4b/0x12d0
 on_each_cpu_cond_mask+0x3f/0x80
 flush_tlb_mm_range+0x6b1/0x12d0
 tlb_flush_mmu+0x1a7/0x680
 tlb_finish_mmu+0xc3/0x1d0
 free_ldt_pgtables+0x17b/0x320
 exit_mmap+0x17c/0xb50
 __mmput+0x118/0x430
 exit_mm+0x1da/0x2c0
 do_exit+0x648/0x2300
 do_group_exit+0x21c/0x2d0
 __x64_sys_exit_group+0x3f/0x40
 x64_sys_call+0x21f7/0x2200
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5f64baea90
Code: Unable to access opcode bytes at 0x7f5f64baea66.
RSP: 002b:00007ffd2c9dbe48 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f5f64c9f860 RCX: 00007f5f64baea90
RDX: 00000000000000e7 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00007f5f64c9f860 R08: 00007ffd2c9dbcc0 R09: 00007ffd2c9dbda0
R10: 00007ffd2c9dbd00 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f5f64ca3658 R15: 0000000000000001
 </TASK>
