syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (1 GPs behind) idle=066/1/0x4000000000000004 softirq=187193/187194 fqs=6 
	(t=10501 jiffies g=300401 q=147)
rcu: rcu_preempt kthread starved for 10489 jiffies! g300401 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     I29056    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:2818 [inline]
 __schedule+0x7cb/0x1560 kernel/sched/core.c:3445
 schedule+0xa8/0x260 kernel/sched/core.c:3509
 schedule_timeout+0x486/0xc50 kernel/time/timer.c:1807
 rcu_gp_fqs_loop kernel/rcu/tree.c:1589 [inline]
 rcu_gp_kthread+0x9b2/0x18b0 kernel/rcu/tree.c:1746
 kthread+0x354/0x420 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 0
CPU: 0 PID: 8284 Comm: syz-executor.4 Not tainted 5.2.0-rc2+ #44
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1be/0x236 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x183/0x1cf kernel/rcu/tree_stall.h:254
 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:529 [inline]
 rcu_pending kernel/rcu/tree.c:2625 [inline]
 rcu_sched_clock_irq.cold+0x4d1/0xbfd kernel/rcu/tree.c:2161
 update_process_times+0x32/0x80 kernel/time/timer.c:1639
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167
 tick_sched_timer+0x47/0x130 kernel/time/tick-sched.c:1298
 __run_hrtimer kernel/time/hrtimer.c:1389 [inline]
 __hrtimer_run_queues+0x33b/0xdd0 kernel/time/hrtimer.c:1451
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline]
 smp_apic_timer_interrupt+0x111/0x550 arch/x86/kernel/apic/apic.c:1066
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:806
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x50 kernel/kcov.c:101
Code: f4 ff ff ff e8 3d 11 ea ff 48 c7 05 de 6a f5 08 00 00 00 00 e9 a4 e9 ff ff 90 90 90 90 90 90 90 90 90 55 48 89 e5 48 8b 75 08 <65> 48 8b 04 25 c0 fd 01 00 65 8b 15 00 59 91 7e 81 e2 00 01 1f 00
RSP: 0018:ffff8880ae809c70 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffff1100cce5825 RBX: dffffc0000000000 RCX: ffffffff864acc36
RDX: 0000000000000100 RSI: ffffffff864acbfd RDI: ffff88806672c128
RBP: ffff8880ae809c70 R08: ffff8880491a02c0 R09: ffffed1015d0137e
R10: ffffed1015d0137d R11: 0000000000000003 R12: ffff88806672c128
R13: 00000000fffff034 R14: ffff88809afb4000 R15: 0000000000000000
 rose_find_socket+0x7d/0x120 net/rose/af_rose.c:281
 rose_loopback_timer+0x336/0x480 net/rose/rose_loopback.c:94
 call_timer_fn+0x193/0x720 kernel/time/timer.c:1322
 expire_timers kernel/time/timer.c:1366 [inline]
 __run_timers kernel/time/timer.c:1685 [inline]
 __run_timers kernel/time/timer.c:1653 [inline]
 run_timer_softirq+0x66f/0x1740 kernel/time/timer.c:1698
 __do_softirq+0x25c/0x94c kernel/softirq.c:293
 invoke_softirq kernel/softirq.c:374 [inline]
 irq_exit+0x180/0x1d0 kernel/softirq.c:414
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0x13b/0x550 arch/x86/kernel/apic/apic.c:1068
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:806
 </IRQ>
RIP: 0010:debug_lockdep_rcu_enabled+0x26/0xa0 kernel/rcu/update.c:236
Code: 00 00 00 00 48 c7 c0 64 88 80 89 55 48 ba 00 00 00 00 00 fc ff df 48 89 c1 83 e0 07 48 89 e5 48 c1 e9 03 83 c0 03 0f b6 14 11 <38> d0 7c 04 84 d2 75 49 8b 15 80 fc 22 08 85 d2 74 3b 48 c7 c0 74
RSP: 0018:ffff8880671c7668 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000007 RBX: ffffea0001b56940 RCX: 1ffffffff130110c
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000286
RBP: ffff8880671c7668 R08: 00000000d22d0c1d R09: ffff8880491a0b88
R10: ffff8880491a0b68 R11: ffff8880491a02c0 R12: ffffea0001b56940
R13: ffffea0001b56948 R14: 0000000000000000 R15: dead000000000100
 rcu_read_lock+0x2e/0x70 include/linux/rcupdate.h:596
 lock_page_memcg+0x19/0x1d0 mm/memcontrol.c:1984
 page_remove_file_rmap mm/rmap.c:1218 [inline]
 page_remove_rmap+0x53d/0x1090 mm/rmap.c:1303
 zap_pte_range mm/memory.c:1093 [inline]
 zap_pmd_range mm/memory.c:1195 [inline]
 zap_pud_range mm/memory.c:1224 [inline]
 zap_p4d_range mm/memory.c:1245 [inline]
 unmap_page_range+0xd3b/0x22f0 mm/memory.c:1266
 unmap_single_vma+0x19d/0x300 mm/memory.c:1311
 unmap_vmas+0x135/0x280 mm/memory.c:1343
 exit_mmap+0x2ad/0x510 mm/mmap.c:3145
 __mmput kernel/fork.c:1059 [inline]
 mmput+0x15f/0x4c0 kernel/fork.c:1080
 exit_mm kernel/exit.c:547 [inline]
 do_exit+0x816/0x2fa0 kernel/exit.c:864
 do_group_exit+0x135/0x370 kernel/exit.c:981
 get_signal+0x41e/0x2240 kernel/signal.c:2638
 do_signal+0x87/0x1900 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459279
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f568e65ecf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000001 RBX: 000000000075bf28 RCX: 0000000000459279
RDX: 00000000004c7f9b RSI: 0000000000000081 RDI: 000000000075bf2c
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000211d49 R11: 0000000000000246 R12: 000000000075bf2c
R13: 00007ffd5e3d782f R14: 00007f568e65f9c0 R15: 000000000075bf2c