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Wed, 19 Aug 2026 02:55:24 +0000 X-Migadu-Flow: FLOW_OUT From: Ye Liu To: Pasha Tatashin , Andrew Morton , Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: Ye Liu , Alexandre Ghiti , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: [RESEND PATCH] mm/page_table_check: add explicit pmd_none check in pte_clear_range Date: Wed, 19 Aug 2026 10:55:15 +0800 Message-Id: <20260819025516.2967199-1-ye.liu@linux.dev> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: DBDA6100007 X-Stat-Signature: aoz63j98jywj1eq3u51gfotbxch17awf X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1787108135-109337 X-HE-Meta: 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 fqzZDF3M pKEXh+4m2H2AEU0sSFeNy2KErCE+eA7PuyfVSQnZiEcpW9V/7/VCuiNjrpDiKrz/F5TNKb+bwDApYW7kAwiJLTdPeNupZnBJ2mg+fhjh2A/XnV4tEvbFfmE33aIU9KzXNknCD71Q9sL70NBhk3PWBYfmOaSePEB8zzVwxCF2Q/XEykSb1h+KMdv/icoZbC9QLtP+mCyw4AyL2LKgswQc8MXgOIeuVN318V3pp8sCVZiR3soMI4XNVpgBo/OySH1gadcRD5JK/NGXOEL+x6AXXIOdsqw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Ye Liu In __page_table_check_pte_clear_range(), the condition to determine whether to iterate over PTEs only checked pmd_bad() and pmd_leaf(). This relies on the implicit assumption that pmd_none() is always a subset of pmd_bad() on all architectures supporting PAGE_TABLE_CHECK. While this assumption currently holds for x86_64, arm64, s390, riscv, and powerpc, it is an architecture-dependent behavior that may not hold for future architectures. Add an explicit pmd_none() check to make the intent clear and avoid calling pte_offset_map() on an empty PMD, which could lead to undefined behavior. Signed-off-by: Ye Liu --- mm/page_table_check.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/page_table_check.c b/mm/page_table_check.c index 6ffc536359cd..ed3e1a76f266 100644 --- a/mm/page_table_check.c +++ b/mm/page_table_check.c @@ -278,7 +278,7 @@ void __page_table_check_pte_clear_range(struct mm_struct *mm, if (&init_mm == mm) return; - if (!pmd_bad(pmd) && !pmd_leaf(pmd)) { + if (!pmd_none(pmd) && !pmd_bad(pmd) && !pmd_leaf(pmd)) { pte_t *ptep = pte_offset_map(&pmd, addr); unsigned long i; -- 2.25.1