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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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 22822C5DF81 for ; Wed, 19 Aug 2026 02:55:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=MUHlbpgEBpQSgpxNyl1CbO1z8i2ZwS1ifKfnXFqmdvU=; b=goELSJ9u4dO0ZA r3FoKVYHdn7wAvIGfu8vk4mBabRHMvQeHHKcPJiV8TUDemBoz5i7VZ2y4MdWWV/045mkCQeM/gBx6 Pz0UhuYoDB8cg6Kx9hqD1GQ+v49wBJVbfkrxiVzl70UHtZ05NPefVmr9G+QJb//seGEp8k32XkTL4 dxDh4mMUanvFRd5eSjtdOUkq5W2iiNeyzOH19mGKO9XAoKKqnkMOvyoqMJX5bAeu/dPeaESn0snCw lzbPbh5yiId9VY5gdZNVGcv3mANLVTgvienKaFAaaZQOiKgzMDi1z+KeQt5pZSdDk6ZE7MPPjp2l9 z5vi2fcQ7c4LDsoerG6Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wwWSk-00000008ugU-3z1F; Wed, 19 Aug 2026 02:55:37 +0000 Received: from out-60.mta0.migadu.com ([2001:41d0:1004:224b::3c] helo=mta0.migadu.com) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wwWSg-00000008ufr-1JoD for linux-riscv@lists.infradead.org; Wed, 19 Aug 2026 02:55:33 +0000 X-Envelope-To: linux-riscv@lists.infradead.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=1787108124; v=1; x=1787712924; b=tXSfet5IVoMqW4YaMXPNZHiCcIWhYvxhUsxmKN0dAUJY0MEUT8G9z97kbF7tpwAqbTKzHI0m QXs+8J2RKEf53Nh4j/Yopi1/QTGBBRBwagGbQCio9aiTc3WuNBdPEvvIuJY7Zom2uF2PeOaLzbH umI7qTXim9mY+ewNCkzyDxmc= X-Envelope-To: linux-riscv@lists.infradead.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 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260818_195530_672100_EAC09CF0 X-CRM114-Status: UNSURE ( 9.74 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org 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 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv