syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	3-....: (10458 ticks this GP) idle=17e/1/0x4000000000000002 softirq=15502/15502 fqs=5149 
	(t=10502 jiffies g=9441 q=258)
NMI backtrace for cpu 3
CPU: 3 PID: 10733 Comm: syz-executor.1 Not tainted 5.4.0-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:2827 [inline]
 rcu_sched_clock_irq.cold+0x509/0xc02 kernel/rcu/tree.c:2271
 update_process_times+0x2d/0x70 kernel/time/timer.c:1726
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167
 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1310
 __run_hrtimer kernel/time/hrtimer.c:1514 [inline]
 __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1576
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1638
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:preempt_schedule_irq+0xab/0x160 kernel/sched/core.c:4338
Code: 00 00 e8 d8 d8 d4 f9 e8 43 b5 fe f9 4c 89 f0 48 c1 e8 03 80 3c 18 00 75 7d 48 83 3d 96 81 97 01 00 74 6f fb 66 0f 1f 44 00 00 <bf> 01 00 00 00 e8 0b d2 ff ff 48 c7 c0 60 34 13 89 48 c1 e8 03 80
RSP: 0018:ffff88806aca7438 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff122668d RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000006 RDI: ffff88800bc98bd4
RBP: ffff88806aca7458 R08: ffff88800bc98340 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffed1001793068
R13: ffff88800bc98340 R14: ffffffff89133468 R15: 0000000000000000
 retint_kernel+0x1b/0x2b
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline]
RIP: 0010:free_unref_page_list+0x52e/0x800 mm/page_alloc.c:3109
Code: 68 5a d1 ff 48 8b 45 a8 48 c1 e8 03 80 3c 18 00 0f 85 b3 02 00 00 48 83 3d a6 26 6a 07 00 0f 84 fc 00 00 00 48 8b 7d c0 57 9d <0f> 1f 44 00 00 e9 50 fe ff ff 48 89 d8 48 c7 45 a8 58 34 13 89 25
RSP: 0018:ffff88806aca7510 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff122668b RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000282
RBP: ffff88806aca7568 R08: ffff88800bc98340 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffea0001aa7880
R13: ffffea0001aa7840 R14: ffffea0001aa7888 R15: 0000000000000020
 release_pages+0xf21/0x1bd0 mm/swap.c:842
 free_pages_and_swap_cache+0x2c3/0x3f0 mm/swap_state.c:296
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:184 [inline]
 tlb_flush_mmu+0x89/0x630 mm/mmu_gather.c:191
 zap_pte_range mm/memory.c:1140 [inline]
 zap_pmd_range mm/memory.c:1178 [inline]
 zap_pud_range mm/memory.c:1207 [inline]
 zap_p4d_range mm/memory.c:1228 [inline]
 unmap_page_range+0x1c61/0x2ac0 mm/memory.c:1249
 unmap_single_vma+0x19d/0x300 mm/memory.c:1294
 unmap_vmas+0x184/0x2f0 mm/memory.c:1326
 exit_mmap+0x2ba/0x530 mm/mmap.c:3161
 __mmput kernel/fork.c:1079 [inline]
 mmput+0x179/0x4d0 kernel/fork.c:1100
 exit_mm kernel/exit.c:485 [inline]
 do_exit+0x806/0x2ef0 kernel/exit.c:784
 do_group_exit+0x135/0x360 kernel/exit.c:895
 get_signal+0x47c/0x24f0 kernel/signal.c:2734
 do_signal+0x87/0x1700 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x286/0x380 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x676/0x790 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a759
Code: Bad RIP value.
RSP: 002b:00007f4049026c88 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: 0000000000000009 RBX: 000000000071c0f8 RCX: 000000000045a759
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 000000002001d000
RBP: 0000000000000005 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 00007f40490276d4
R13: 00000000004aec17 R14: 00000000006f1cb0 R15: 00000000ffffffff