From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-36.mta1.migadu.com [95.215.58.36]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7029D208D0 for ; Wed, 19 Aug 2026 02:55:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.36 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787108138; cv=none; b=XnJ97y3fgBXNR4Xbwd0bYW7eM25zzsCj0ctpkAUHoxyU5UQNCsdv3Oe/8SA8v2n++E4JEWNZZl0qAxzF78azZ7pI4ldnxXb7DePvTKWLUPKfUEuYsldvAwUG3Xq00ea5a2f7trYRSZud7stt0Sdneh6Nz4xc3a4ua/rgquJSfqk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787108138; c=relaxed/simple; bh=3S5O+WmFCYTlfNAAGG8hR3gIY7XgRoq+MHcx43aEOyU=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=hdcSkPfzgnyVOwiobp7Tteg+flSt8omoXOxEYkTsYDOoxaeIwG8pfJcNKrVLthnfAHHBlCsOmcgL5yyTUpFGwFgq0nSnlwH/70WhF3KZlHHHszkj4fmF3nATbv1OjvjIf6CknFNGe2kLSBEmUkVG0xyKjeHB1buMgI/c8hE5p8Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=sWzsNKUY; arc=none smtp.client-ip=95.215.58.36 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="sWzsNKUY" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=3S5O+WmFCYTlfNAAGG8hR3gIY7XgRoq+MHcx43aEOyU=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1787108134; v=1; x=1787712934; b=sWzsNKUYwhwa2tA4WrFgkElEP4ujCKXDuzDgc1GltC7mQYovHgzLz2bkceKAJzisJRLwGdTK 8wcZvn0dxi2NXWkKw+dTxr+5Z6Ch2KeQmqZ0EoZCQNqGEsEaCBPMZWy9yU+VZxkBfl25YOYz1+Q sThh9w+IToPJBpApEU1LGv+Y= X-Envelope-To: linux-kernel@vger.kernel.org Received: from localhost.localdomain (223.70.159.239) by smtp.migadu.com with ESMTPS id ab08ddb189ee31a0; 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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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