From 9f2bad096d2f84751fd4559fcd4cdda1a2af1976 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@google.com>
Date: Thu, 8 Jun 2023 18:27:52 -0700
Subject: mm/debug_vm_pgtable,page_table_check: warn pte map fails
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Failures here would be surprising: pte_advanced_tests() and
pte_clear_tests() and __page_table_check_pte_clear_range() each issue a
warning if pte_offset_map() or pte_offset_map_lock() fails.

Link: https://lkml.kernel.org/r/3ea9e4f-e5cf-d7d9-4c2-291b3c5a3636@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/page_table_check.c | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'mm/page_table_check.c')

diff --git a/mm/page_table_check.c b/mm/page_table_check.c
index 25d8610c0042..0c511330dbc9 100644
--- a/mm/page_table_check.c
+++ b/mm/page_table_check.c
@@ -240,6 +240,8 @@ void __page_table_check_pte_clear_range(struct mm_struct *mm,
 		pte_t *ptep = pte_offset_map(&pmd, addr);
 		unsigned long i;
 
+		if (WARN_ON(!ptep))
+			return;
 		for (i = 0; i < PTRS_PER_PTE; i++) {
 			__page_table_check_pte_clear(mm, addr, *ptep);
 			addr += PAGE_SIZE;
-- 
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