From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794482757; b=0W2MBNjov/UOzXCFUlkBU4hlk3KZUutpsZGZaCdrgTXE4WD31ZvdsNUNlTviuXNZmzpk gQsitnw/8Iqkj2BCkOlSRA4uEAiDxEp2XoNeYtFz6GKiSJBo3you/yk8V/0MLy0Jm3gpC GeLgb5ddOgZoaQP0sruoAjBMgEv139fdUpJYFtUhnoCgyGRWc4bsBUaLuqO2+vX1OroXS Gu2/eb5hEUlOH/aGzNfQu9qJdxUmX4drMumj4HeHlP+IMuw9ys4yYTt5rbdThzYdWLd+C mB6E7MBcICnku5OSXdpHQtaiMaxnUmAAj5SljuK6QiE1bR5KIVmMJ1vfB+loNa0ZuDg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794482757; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=FD/V4+e8O0iqTKVI3Ylc4RORwqMbtboEEa/TKhMeE7M=; b=Ze6Msoh5sco/+xhcPPMepPalM92OGmLdzus4FEWeWBTCHs/2BcOG6XhmEnehV1F1N0af NYvBL7LbbpJT4vM/UNwfAF1+ArbJsJQhw7tawE6gf9Czfq1fQ4Uk8YibFsyCeQtp+4cnY UdnKYXyrVSlreAJv1mpuOwL7EiERlFpYFDd6jPAGwMZvls/U2hhS56gIQxnWS/1tK6M06 R5UJCuUBp2vuQ/AcLN2ituavV1tio7AyNXkuILD1q/kpvb8Bqbe+9dh02YBEjwezmj0Y+ 43FfJxZhOdtv5N5kGon2+oEa2qWRFtt8u1yQtQiv+XdB8r3kxNNWRkoW5Bb9JrxprAg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=JETWMfWj; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 655FA606A89A for ; Thu, 12 Nov 2026 11:25:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=JETWMfWj Received: by smtp.kernel.org (Postfix) with ESMTPSA id 662A91F00A05; Thu, 12 Nov 2026 11:25:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794482757; bh=FD/V4+e8O0iqTKVI3Ylc4RORwqMbtboEEa/TKhMeE7M=; h=From:To:Cc:Subject:Date:In-Reply-To:References; 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-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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