syzbot

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kernel BUG at [] mm/page_table_check.c:142!
Kernel BUG [#1]
Modules linked in:
CPU: 0 UID: 0 PID: 5681 Comm: syz.0.457 Not tainted syzkaller #0 PREEMPT 
Hardware name: riscv-virtio,qemu (DT)
epc : __page_table_check_zero+0x396/0x544 mm/page_table_check.c:142
 ra : __page_table_check_zero+0x396/0x544 mm/page_table_check.c:142
epc : ffffffff80bfdcce ra : ffffffff80bfdcce sp : ffff8f8003e96b90
 gp : ffffffff89f9df20 tp : ffffaf801e678000 t0 : ffff8f8003e96b40
 t1 : fffff5ef02701409 t2 : 0000000000000000 s0 : ffff8f8003e96c00
 s1 : ffffaf801380a048 a0 : 0000000000000005 a1 : 0000000000000000
 a2 : 0000000000000002 a3 : ffffffff80bfdcce a4 : 0000000000000000
 a5 : ffffaf801e679000 a6 : 0000000000000003 a7 : ffffaf801380a04b
 s2 : 0000000000000001 s3 : 0000000000000000 s4 : ffffaf801380a000
 s5 : dfffffff00000000 s6 : 00000000000b8200 s7 : 0000000000000200
 s8 : 0000000000000009 s9 : 0000000000007fff s10: fffffffef1416bb0
 s11: ffffffff8a0b5d80 t3 : 0000000000000001 t4 : fffff5ef02701409
 t5 : fffff5ef0270140a t6 : 0000000000000002 ssp : 0000000000000000
status: 0000000200000120 badaddr: ffffffff80bfdcce cause: 0000000000000003
[<ffffffff80bfdcce>] __page_table_check_zero+0x396/0x544 mm/page_table_check.c:142
[<ffffffff80a775b6>] page_table_check_free include/linux/page_table_check.h:43 [inline]
[<ffffffff80a775b6>] free_pages_prepare mm/page_alloc.c:1434 [inline]
[<ffffffff80a775b6>] free_unref_folios+0xa22/0x1dc8 mm/page_alloc.c:3030
[<ffffffff808aac84>] folios_put_refs+0x41c/0x61c mm/swap.c:1002
[<ffffffff80ac4cec>] free_pages_and_swap_cache+0x29c/0x480 mm/swap_state.c:358
[<ffffffff809e9980>] __tlb_batch_free_encoded_pages+0xe4/0x25c mm/mmu_gather.c:137
[<ffffffff809eb398>] tlb_batch_pages_flush mm/mmu_gather.c:150 [inline]
[<ffffffff809eb398>] tlb_flush_mmu_free mm/mmu_gather.c:398 [inline]
[<ffffffff809eb398>] tlb_flush_mmu+0xdc/0x5f8 mm/mmu_gather.c:405
[<ffffffff809aaf02>] zap_pte_range mm/memory.c:1897 [inline]
[<ffffffff809aaf02>] zap_pmd_range mm/memory.c:1950 [inline]
[<ffffffff809aaf02>] zap_pud_range mm/memory.c:1978 [inline]
[<ffffffff809aaf02>] zap_p4d_range mm/memory.c:1999 [inline]
[<ffffffff809aaf02>] unmap_page_range+0x1b3a/0x408c mm/memory.c:2020
[<ffffffff809ad592>] unmap_single_vma+0x13e/0x230 mm/memory.c:2062
[<ffffffff809ad86e>] unmap_vmas+0x1ea/0x40c mm/memory.c:2104
[<ffffffff809e610c>] exit_mmap+0x184/0xca8 mm/mmap.c:1277
[<ffffffff8013b6aa>] __mmput+0x106/0x3d0 kernel/fork.c:1173
[<ffffffff8013b9e8>] mmput+0x74/0x88 kernel/fork.c:1196
[<ffffffff8015b08e>] exit_mm kernel/exit.c:581 [inline]
[<ffffffff8015b08e>] do_exit+0x792/0x2828 kernel/exit.c:959
[<ffffffff8015d64e>] do_group_exit+0xca/0x258 kernel/exit.c:1112
[<ffffffff801951fa>] get_signal+0x1f7e/0x224c kernel/signal.c:3034
[<ffffffff800726f0>] arch_do_signal_or_restart+0xca0/0x1ddc arch/riscv/kernel/signal.c:534
[<ffffffff803c0aee>] __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
[<ffffffff803c0aee>] exit_to_user_mode_loop+0x8e/0x874 kernel/entry/common.c:75
[<ffffffff86391c9a>] __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
[<ffffffff86391c9a>] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
[<ffffffff86391c9a>] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
[<ffffffff86391c9a>] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
[<ffffffff86391c9a>] do_trap_ecall_u+0x462/0x58c arch/riscv/kernel/traps.c:359
[<ffffffff863bb61e>] handle_exception+0x15e/0x16a arch/riscv/kernel/entry.S:232
Code: 7f80 8526 c0ef ec3f 8a2a b791 6097 ff90 80e7 7e60 (9002) 6097 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	7f80                	flw	fs0,56(a5)
   2:	8526                	mv	a0,s1
   4:	ec3fc0ef          	jal	0xffffffffffffcec6
   8:	8a2a                	mv	s4,a0
   a:	b791                	j	0xffffffffffffff4e
   c:	ff906097          	auipc	ra,0xff906
  10:	7e6080e7          	jalr	2022(ra) # 0xff9067f2
* 14:	9002                	ebreak <-- trapping instruction
  16:	9760                	.short	0x6097