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 265DCC4450A for ; Tue, 14 Jul 2026 14:07:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References :Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=2AtuGnMkKUmg5Fcb42sI1/yhBOPgS1GscsBtzFqMWqA=; b=rBNRWAs1rn/DDqddQzwlwiaRnh DPplL/eTBc0pU3Qe9F5DKUYDaCZ/iuY91oww4TlSSeb1aXrxCh1cUR+boykVnROHW53k/9wGti473 cuoD7lqAr4Jm4RuW0GOOh+2iLoa1b6AH9JgmW4/fQMMmnMj/ZCGqVFbJMXkxKg2CsJFcdTM1XuLdr LeuCFHw5KZ2lyMrtwBDY+l2bKCLxwRWdTNFzpRT9l/Ejw4j8ZjSTmY5nOkWPHPQgoE6+zpHyDse9h FXmyWQqtYQzvAHg5JA0gaclYxk7alycJDgkWLr6ASd22zurJZcewKs0rBnla1fh7DxX+IznAtKTgV 7j85V9uw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wjdnC-0000000CJbR-30yC; Tue, 14 Jul 2026 14:07:26 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wjdn8-0000000CJVx-0r1d; Tue, 14 Jul 2026 14:07:25 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 49CFE1CDD; Tue, 14 Jul 2026 07:07:17 -0700 (PDT) Received: from localhost.localdomain (e123572-lin.cambridge.arm.com [10.2.208.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 211913FBB1; Tue, 14 Jul 2026 07:07:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784038041; bh=W5yMHnXfWcnH1ZpiyUJxzPFiGyzR0nmofTO/4v3XglM=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=tcs2QjbOfi2UrOaEb3Be0yDpY6GZomCe7QbbhuAt79rvxsFv0nPzL+CWkgYpCVks/ ogkFHzzFifaJTeH1MCRm+XyD/611Im1Ut2kp5sQ9dzHO1o7eUkGFrrRiH6Z4V/RDtz /vlFqoX8JwYVcEUc2qvYwpr+Gn4LoNg3DQ/uWfI4= From: Kevin Brodsky Date: Tue, 14 Jul 2026 15:04:06 +0100 Subject: [PATCH 17/22] mm: pagewalk: drop redundant address check for kernel mm walks MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260714-remove_pgtable_cdtor-v1-17-44be8a7685d7@arm.com> References: <20260714-remove_pgtable_cdtor-v1-0-44be8a7685d7@arm.com> In-Reply-To: <20260714-remove_pgtable_cdtor-v1-0-44be8a7685d7@arm.com> To: linux-mm@kvack.org Cc: Kevin Brodsky , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Pasha Tatashin , Russell King , Catalin Marinas , Will Deacon , Ryan Roberts , linux-arm-kernel@lists.infradead.org, Huacai Chen , loongarch@lists.linux.dev, "James E.J. Bottomley" , Helge Deller , linux-parisc@vger.kernel.org, Madhavan Srinivasan , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-riscv@lists.infradead.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Gerald Schaefer , linux-s390@vger.kernel.org, "David S. Miller" , Andreas Larsson , sparclinux@vger.kernel.org, Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Ning Sun , x86@kernel.org, tboot-devel@lists.sourceforge.net, Ard Biesheuvel , Ilias Apalodimas , linux-efi@vger.kernel.org, Vishal Moola , Alistair Popple , "Matthew Wilcox (Oracle)" , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1784037902; l=1902; i=kevin.brodsky@arm.com; s=20260427; h=from:subject:message-id; bh=W5yMHnXfWcnH1ZpiyUJxzPFiGyzR0nmofTO/4v3XglM=; b=TFBgeJD80Ix+w11MAOvfP3+Vh87dI14Hnq0FHr8NrSRBwD9XPKoZw/aAqVJc1+sG5OV8cIA+P hlg2L1E8nGiAdR9B4tzknmDLhA26Dhv64+3Fs4YGAcZ8Y3UcdoWIKP6 X-Developer-Key: i=kevin.brodsky@arm.com; a=ed25519; pk=N2QG+eJKrvkNovwhhwJhnJ4+ScVfsGCHldmqLfcMTFs= X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260714_070722_361770_0E56D3C9 X-CRM114-Status: GOOD ( 13.56 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org Commit 8b1cb4a2e819 ("mm/pagewalk: fix EFI_PGT_DUMP of espfix area") made no-VMA page table walks use pte_offset_kernel() for any address above TASK_SIZE. This avoided pte_offset_map() validation on EFI page table dumps, where efi_mm could walk x86 espfix PMDs that intentionally look bad to pmd_bad(). efi_mm is now marked with MMF_KERNEL, and no-VMA walks use mm_is_kernel() to select pte_offset_kernel() for kernel mm's. As a result we no longer need to handle the EFI_PGT_DUMP case explicitly.The address check is therefore redundant for EFI_PGT_DUMP and makes the condition harder to reason about. Remove the address check and associated comment; mm_is_kernel() should be sufficient on its own. Tested by booting x86 QEMU with CONFIG_EFI_PGT_DUMP=y and reading /sys/kernel/debug/page_tables/efi. Assisted-by: Codex:GPT-5.5 Signed-off-by: Kevin Brodsky --- mm/pagewalk.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/mm/pagewalk.c b/mm/pagewalk.c index a3f47d1de3c5..0dd9d4ad9b68 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -68,17 +68,14 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, if (walk->no_vma) { /* * pte_offset_map() might apply user-specific validation. - * Indeed, on x86_64 the pmd entries set up by init_espfix_ap() - * fit its pmd_bad() check (_PAGE_NX set and _PAGE_RW clear), - * and CONFIG_EFI_PGT_DUMP efi_mm goes so far as to walk them. */ - if (mm_is_kernel(walk->mm) || addr >= TASK_SIZE) + if (mm_is_kernel(walk->mm)) pte = pte_offset_kernel(pmd, addr); else pte = pte_offset_map(pmd, addr); if (pte) { err = walk_pte_range_inner(pte, addr, end, walk); - if (!mm_is_kernel(walk->mm) && addr < TASK_SIZE) + if (!mm_is_kernel(walk->mm)) pte_unmap(pte); } } else { -- 2.51.2