rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (2 ticks this GP) idle=a87c/1/0x4000000000000000 softirq=17445/17447 fqs=6
rcu: 	(detected by 1, t=10505 jiffies, g=9709, q=80 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6324 Comm: syz.1.121 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:mark_lock+0x26/0x190
Code: 90 90 90 90 55 41 57 41 56 41 55 41 54 53 8b 46 20 89 c1 81 e1 00 00 03 00 83 f9 01 bb 09 00 00 00 83 db 00 83 fa 08 0f 45 da <bd> 01 00 00 00 89 d9 d3 e5 25 ff 1f 00 00 48 0f a3 05 c4 0f 0b 12
RSP: 0018:ffffc90000007718 EFLAGS: 00000093
RAX: 00000000000c4067 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff88810a52c4c0 RDI: ffff88810a52b980
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff81adabcb
R10: dffffc0000000000 R11: ffffed1009604f51 R12: 0000000000000002
R13: 0000000000000002 R14: ffff88810a52c4c0 R15: 0000000000000000
FS:  00007f623157e6c0(0000) GS:ffff8880b8611000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3a5c23 CR3: 0000000022336000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 __lock_acquire+0x65a/0xd20
 lock_acquire+0x120/0x360
 _raw_spin_lock_irqsave+0xa7/0xf0
 hrtimer_try_to_cancel+0x22b/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:__handle_mm_fault+0x145b/0x5440
Code: 4d 89 fe 49 c1 ee 03 49 bc 00 00 00 00 00 fc ff df 43 80 3c 26 00 74 08 4c 89 ff e8 0f 10 18 00 49 8b 1f 48 89 de 48 83 e6 08 <31> ff e8 2e f0 b3 ff 48 83 e3 08 0f 85 ab 03 00 00 4c 89 74 24 50
RSP: 0018:ffffc90002e6f380 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000008100077 RCX: 098b8e4cf6692f00
RDX: 0000000000000002 RSI: 0000000000000000 RDI: ffff88810a52b980
RBP: ffffc90002e6f560 R08: 0000000000000000 R09: ffffffff8210bda9
R10: ffffc90002e6f48c R11: fffff520005cde9a R12: dffffc0000000000
R13: ffff888027b19980 R14: 1ffff11004f63334 R15: ffff888027b199a0
 handle_mm_fault+0x40a/0x8e0
 do_user_addr_fault+0x764/0x1390
 exc_page_fault+0x76/0xf0
 asm_exc_page_fault+0x26/0x30
RIP: 0010:rep_movs_alternative+0x75/0x90
Code: 05 c3 cc cc cc cc 48 8b 06 48 89 07 48 8d 47 08 48 83 e0 f8 48 29 f8 48 01 c7 48 01 c6 48 29 c1 48 89 c8 48 c1 e9 03 83 e0 07 <f3> 48 a5 89 c1 85 c9 75 91 c3 cc cc cc cc 48 8d 0c c8 eb 86 cc cc
RSP: 0018:ffffc90002e6f798 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888031a00028 RCX: 00000000000005b1
RDX: 0000000000000001 RSI: 0000200000095000 RDI: ffff888031a05278
RBP: ffffc90002e6f910 R08: ffff888031a07fff R09: 1ffff11006340fff
R10: dffffc0000000000 R11: ffffed1006341000 R12: 1ffff920005cdf77
R13: 000020000008fdb0 R14: ffffc90002e6fbc8 R15: 0000000000007fd8
 _copy_from_iter+0x24f/0x1790
 mptcp_sendmsg+0xd6e/0x1970
 __sock_sendmsg+0x19c/0x270
 sock_write_iter+0x258/0x330
 vfs_write+0x5c9/0xb30
 ksys_write+0x145/0x250
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f623078ec29
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:00007f623157e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f62309d5fa0 RCX: 00007f623078ec29
RDX: 000000011ffffce1 RSI: 0000200000000080 RDI: 0000000000000006
RBP: 00007f6230811e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f62309d6038 R14: 00007f62309d5fa0 R15: 00007ffd9e571938
 </TASK>
rcu: rcu_preempt kthread starved for 10475 jiffies! g9709 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:27848 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: 1 UID: 0 PID: 6326 Comm: syz.0.119 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 63 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 61 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 45 5f
RSP: 0018:ffffc9000249f300 EFLAGS: 00000293
RAX: ffffffff81b4665b RBX: 1ffff11009608341 RCX: ffff888020fc0000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000249f480 R08: ffffffff8fa3b537 R09: 1ffffffff1f476a6
R10: dffffc0000000000 R11: fffffbfff1f476a7 R12: ffff88804b041a08
R13: dffffc0000000000 R14: ffff88813663b1c0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881a3c11000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c269ed9 CR3: 000000000df36000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 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
 get_signal+0x1286/0x1340
 arch_do_signal_or_restart+0x9a/0x750
 irqentry_exit_to_user_mode+0x81/0x120
 exc_general_protection+0x171/0x200
 asm_exc_general_protection+0x26/0x30
RIP: 0033:0x7ffb5d78ec31
Code: Unable to access opcode bytes at 0x7ffb5d78ec07.
RSP: 002b:0000200000000010 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007ffb5d9d6090 RCX: 00007ffb5d78ec29
RDX: 0000200000000040 RSI: 0000200000000010 RDI: 0000000000808000
RBP: 00007ffb5d811e41 R08: 0000200000000180 R09: 0000200000000180
R10: 0000200000000080 R11: 0000000000000206 R12: 0000000000000000
R13: 00007ffb5d9d6128 R14: 00007ffb5d9d6090 R15: 00007ffea11b7b68
 </TASK>
