rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=5d4c/1/0x4000000000000000 softirq=92256/92256 fqs=38
rcu: 	(detected by 0, t=10506 jiffies, g=76329, q=99 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 22200 Comm: syz.9.2940 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:its_return_thunk+0x0/0x10
Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc <c3> cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 e9 6b 13 b7 f5 cc
RSP: 0018:ffffc900001e0d10 EFLAGS: 00000006
RAX: ffffffff81ade57e RBX: ffff88812adf7340 RCX: ffff88802a8f0000
RDX: 0000000000010000 RSI: 0000000000000000 RDI: ffff88812adf7340
RBP: ffffc900001e0e90 R08: ffff88812adf7357 R09: 0000000000000000
R10: ffff88812adf7340 R11: ffffed10255bee6b R12: ffff88812adf7340
R13: dffffc0000000000 R14: 187a4701f0000000 R15: ffff888136627c80
FS:  0000000000000000(0000) GS:ffff8881a3c1b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fea561b5fac CR3: 000000000df36000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 debug_deactivate+0xe/0x200
 __hrtimer_run_queues+0x2b0/0xc60
 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:lock_acquire+0x58/0x360
Code: 8b 05 8c f5 02 11 48 89 44 24 58 0f 1f 44 00 00 65 8b 05 8f f5 02 11 83 f8 08 0f 83 b8 01 00 00 89 c0 48 0f a3 05 78 28 06 0e <73> 16 e8 61 02 09 00 84 c0 75 0d f6 05 97 0e f0 0d 01 0f 84 d7 01
RSP: 0018:ffffc900070e7278 EFLAGS: 00000297
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e139f60
RBP: ffffffff822e592a R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff940008d1a59 R12: 0000000000000002
R13: ffffffff8e139f60 R14: 0000000000000000 R15: 0000000000000000
 pfn_valid+0xd6/0x490
 page_table_check_clear+0x21/0x700
 unmap_page_range+0x3445/0x4370
 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: 0033:0x7fea55f8ebe9
Code: Unable to access opcode bytes at 0x7fea55f8ebbf.
RSP: 002b:00007fea56de20e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fea561b5fa8 RCX: 00007fea55f8ebe9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fea561b5fa8
RBP: 00007fea561b5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fea561b6038 R14: 00007fff45c09680 R15: 00007fff45c09768
 </TASK>
rcu: rcu_preempt kthread starved for 10315 jiffies! g76329 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:27496 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:
CPU: 0 UID: 0 PID: 8482 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:smp_call_function_many_cond+0xd33/0x12d0
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 b6 62 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 61 5e 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 45 5e
RSP: 0000:ffffc900043df720 EFLAGS: 00000293
RAX: ffffffff81b44ceb RBX: 1ffff11026cc7f61 RCX: ffff888027e43980
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900043df8a0 R08: ffffffff8fa38337 R09: 1ffffffff1f47066
R10: dffffc0000000000 R11: fffffbfff1f47067 R12: ffff88813663fb08
R13: dffffc0000000000 R14: ffff88804b03b1c0 R15: 0000000000000001
FS:  0000555561ecd500(0000) GS:ffff8880b861b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555561ee85c8 CR3: 0000000035862000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80
 flush_tlb_mm_range+0x6b1/0x12d0
 ptep_clear_flush+0x120/0x170
 do_wp_page+0x1bc2/0x5800
 __handle_mm_fault+0x1033/0x5440
 handle_mm_fault+0x40a/0x8e0
 do_user_addr_fault+0xa81/0x1390
 exc_page_fault+0x76/0xf0
 asm_exc_page_fault+0x26/0x30
RIP: 0033:0x7f79bc14d06f
Code: 8d 34 19 48 39 d5 48 89 75 60 0f 95 c2 48 29 d8 48 83 c1 10 0f b6 d2 48 83 c8 01 48 c1 e2 02 48 09 da 48 83 ca 01 48 89 51 f8 <48> 89 46 08 eb 80 48 8d 0d f1 e8 0e 00 48 8d 15 f5 fa 0e 00 bf 01
RSP: 002b:00007ffdba4dca40 EFLAGS: 00010206
RAX: 0000000000018a41 RBX: 0000000000008040 RCX: 0000555561ee0590
RDX: 0000000000008041 RSI: 0000555561ee85c0 RDI: 0000000000000004
RBP: 00007f79bc387cc0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000001000 R11: 0000000000000802 R12: 0000000000008030
R13: 0000000000000076 R14: 00007f79bc387d20 R15: 0000000000000000
 </TASK>
