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b=JETWMfWjkKeINJWiPkhAD/QsItp30dH2rFFfUxvvsc0JyhM1taj1AERUtJ/N3Cjs3 AwYVFzZ/m6zQ7KYBU+YiTIl9hTHpftthT74h5Nr4oeuYEHYYSiIf3AXVs+RKZKKHrV mIOmMwkG2K3nP1x7rGrbfTQKpZOVBqfxi9f/LcxqS5J0K6eBwmu7A8mogUZQyc4cgy znPGEVxp9AgLlfDVNExZSLItcLclY123hZKVh9JoHVE3H6OQiccRm+Ibc4Tk7V2+rw AM4h3/ZJfG+Yk80QegP3t50LRsE3vQEfEM9YcerbVpZJF++E9cU7QgrbnSemDfJFmG qhJVBLKkuZ+CQ== From: Arnd Bergmann To: linux-mm@kvack.org Cc: Arnd Bergmann , Andrew Morton , Andreas Larsson , "Christophe Leroy (CS GROUP)" , Dave Hansen , "David Hildenbrand (Arm)" , Jason Gunthorpe , Linus Walleij , "Lorenzo Stoakes (ARM)" , Matthew Wilcox , Malin Jonsson , Richard Weinberger , Russell King , linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org Subject: [PATCH v2 3/6] ARM: drop CONFIG_HIGHPTE support Date: Thu, 12 Nov 2026 12:25:25 +0100 Message-ID: <20261112112528.1116405-4-arnd@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261112112528.1116405-1-arnd@kernel.org> References: <20261112112528.1116405-1-arnd@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E834520002 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Stat-Signature: 36s7xhexywriwq5m6p1orx9j8iwbqw57 X-HE-Tag: 1794482757-956636 X-HE-Meta: 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 ua2y+80w anAD1kBMrA9a8zXZlzhaZITyn/f7d1BXhxaCui2DWOiq150WhMWdafiJiTIu4GhvcNAslQekDgPDfxH1KD662Ov1mL9HWqTHIAQc2QSXCHwOn+dSgQx8u2FdBy+y9Lx1PpOBbriKVbwGP3aBN5TyHWXmIjqI/EWpwJr6YIBTbFN0K4vjdxf3eopnPY6qbXRndde7jiHQAVLgi3wiHW3jsent+K0NVvloGuS7fnJqCn2szBIK5gpfUk2sQmW2n3dSYx3EE+5L9nC02KniCbOdddXNfdtUqnk5e12mA Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 From: Arnd Bergmann CONFIG_HIGHPTE was added in linux-2.6.32, a few years before 64-bit support. At the time it made sense, as the CONFIG_ARM_LPAE option allowed systems with 16GB of memory that made lowmem a particularly scarce resource, and the HIGHPTE implementation gave feature parity with 32-bit x86 and frv machines. Since Arm is the last architecture remaining that uses this, and almost no 32-bit machines support more than 4GB of RAM, the cost of continuing to maintain HIGHPTE seems unjustified, so remove it here to allow simplifying the generic page table handling. Link: https://lore.kernel.org/lkml/20241204103042.1904639-8-arnd@kernel.org/T/#u Signed-off-by: Arnd Bergmann --- I sent a patch to drop HIGHPTE support on x86 today, see https://lore.kernel.org/lkml/20241210144945.2325330-9-arnd@kernel.org/T/#u If that one gets merged, we can merge this one instead of the one that makes HIGHPTE depend on !PREEMPT_RT, but if we decide against the x86 change, then we probably don't want this one either. Signed-off-by: Arnd Bergmann --- arch/arm/Kconfig | 11 ----------- arch/arm/include/asm/pgalloc.h | 8 +------- 2 files changed, 1 insertion(+), 18 deletions(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index fd01ccab9c12..fc66d52d847e 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1225,17 +1225,6 @@ config HIGHMEM If unsure, say n. -config HIGHPTE - bool "Allocate 2nd-level pagetables from highmem" if EXPERT - depends on HIGHMEM && !PREEMPT_RT - default y - help - The VM uses one page of physical memory for each page table. - For systems with a lot of processes, this can use a lot of - precious low memory, eventually leading to low memory being - consumed by page tables. Setting this option will allow - user-space 2nd level page tables to reside in high memory. - config ARM_PAN bool "Enable privileged no-access" depends on MMU diff --git a/arch/arm/include/asm/pgalloc.h b/arch/arm/include/asm/pgalloc.h index a17f01235c29..ef6cb3e6d179 100644 --- a/arch/arm/include/asm/pgalloc.h +++ b/arch/arm/include/asm/pgalloc.h @@ -85,18 +85,12 @@ pte_alloc_one_kernel(struct mm_struct *mm) return pte; } -#ifdef CONFIG_HIGHPTE -#define PGTABLE_HIGHMEM __GFP_HIGHMEM -#else -#define PGTABLE_HIGHMEM 0 -#endif - static inline pgtable_t pte_alloc_one(struct mm_struct *mm) { struct page *pte; - pte = __pte_alloc_one(mm, GFP_PGTABLE_USER | PGTABLE_HIGHMEM); + pte = __pte_alloc_one(mm, GFP_PGTABLE_USER); if (!pte) return NULL; if (!PageHighMem(pte)) -- 2.53.0