linux-kernel - [PATCH v3 10/13 fix2] mm/khugepaged: collapse_pte_mapped_thp() with mmap_read

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Message-ID: <e0197433-8a47-6a65-534d-eda26eeb78b0@google.com>
Date:   Sat, 5 Aug 2023 20:59:27 -0700 (PDT)
From:   Hugh Dickins <hughd@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
cc:     Qi Zheng <zhengqi.arch@...edance.com>,
        Hugh Dickins <hughd@...gle.com>,
        Pasha Tatashin <pasha.tatashin@...een.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Mike Rapoport <rppt@...nel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Matthew Wilcox <willy@...radead.org>,
        David Hildenbrand <david@...hat.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Yang Shi <shy828301@...il.com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Peter Xu <peterx@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Will Deacon <will@...nel.org>, Yu Zhao <yuzhao@...gle.com>,
        Alistair Popple <apopple@...dia.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Steven Price <steven.price@....com>,
        SeongJae Park <sj@...nel.org>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Huang Ying <ying.huang@...el.com>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Zack Rusin <zackr@...are.com>, Jason Gunthorpe <jgg@...pe.ca>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Minchan Kim <minchan@...nel.org>,
        Christoph Hellwig <hch@...radead.org>,
        Song Liu <song@...nel.org>,
        Thomas Hellstrom <thomas.hellstrom@...ux.intel.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Michael Ellerman <mpe@...erman.id.au>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
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        Vlastimil Babka <vbabka@...e.cz>, Zi Yan <ziy@...dia.com>,
        linux-arm-kernel@...ts.infradead.org, sparclinux@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH v3 10/13 fix2] mm/khugepaged: collapse_pte_mapped_thp() with
 mmap_read_lock(): fix2

Use ptep_clear() instead of pte_clear(): when CONFIG_PAGE_TABLE_CHECK=y,
ptep_clear() adds some accounting, missing which would cause a BUG later.

Signed-off-by: Hugh Dickins <hughd@...gle.com>
Reported-by: Qi Zheng <zhengqi.arch@...edance.com>
Closes: https://lore.kernel.org/linux-mm/0df84f9f-e9b0-80b1-4c9e-95abc1a73a96@bytedance.com/
---
 mm/khugepaged.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index bb76a5d454de..78fc1a24a1cc 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1603,7 +1603,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
 		 * TLB flush can be left until pmdp_collapse_flush() does it.
 		 * PTE dirty? Shmem page is already dirty; file is read-only.
 		 */
-		pte_clear(mm, addr, pte);
+		ptep_clear(mm, addr, pte);
 		page_remove_rmap(page, vma, false);
 		nr_ptes++;
 	}
-- 
2.35.3