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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76A61C43387 for ; Sat, 12 Jan 2019 12:56:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 489342086C for ; Sat, 12 Jan 2019 12:56:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725920AbfALM4B (ORCPT ); Sat, 12 Jan 2019 07:56:01 -0500 Received: from foss.arm.com ([217.140.101.70]:42140 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725823AbfALM4A (ORCPT ); Sat, 12 Jan 2019 07:56:00 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 08DDE80D; Sat, 12 Jan 2019 04:56:00 -0800 (PST) Received: from [10.162.40.80] (p8cg001049571a15.blr.arm.com [10.162.40.80]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 21A493F70D; Sat, 12 Jan 2019 04:55:49 -0800 (PST) Subject: Re: [PATCH] mm: Introduce GFP_PGTABLE To: Matthew Wilcox Cc: linux-mm@kvack.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-sh@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux@armlinux.org.uk, catalin.marinas@arm.com, will.deacon@arm.com, mpe@ellerman.id.au, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, peterz@infradead.org, christoffer.dall@arm.com, marc.zyngier@arm.com, kirill@shutemov.name, rppt@linux.vnet.ibm.com, mhocko@suse.com, ard.biesheuvel@linaro.org, mark.rutland@arm.com, steve.capper@arm.com, james.morse@arm.com, robin.murphy@arm.com, aneesh.kumar@linux.ibm.com, vbabka@suse.cz, shakeelb@google.com, rientjes@google.com References: <1547288798-10243-1-git-send-email-anshuman.khandual@arm.com> <20190112121230.GQ6310@bombadil.infradead.org> From: Anshuman Khandual Message-ID: <9dd9a8ef-8db8-891c-79a9-270ab033037c@arm.com> Date: Sat, 12 Jan 2019 18:25:48 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190112121230.GQ6310@bombadil.infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/12/2019 05:42 PM, Matthew Wilcox wrote: > On Sat, Jan 12, 2019 at 03:56:38PM +0530, Anshuman Khandual wrote: >> All architectures have been defining their own PGALLOC_GFP as (GFP_KERNEL | >> __GFP_ZERO) and using it for allocating page table pages. > > Except that's not true. > >> +++ b/arch/x86/mm/pgtable.c >> @@ -13,19 +13,17 @@ phys_addr_t physical_mask __ro_after_init = (1ULL << __PHYSICAL_MASK_SHIFT) - 1; >> EXPORT_SYMBOL(physical_mask); >> #endif >> >> -#define PGALLOC_GFP (GFP_KERNEL_ACCOUNT | __GFP_ZERO) >> - >> #ifdef CONFIG_HIGHPTE > > ... > >> pte_t *pte_alloc_one_kernel(struct mm_struct *mm) >> { >> - return (pte_t *)__get_free_page(PGALLOC_GFP & ~__GFP_ACCOUNT); >> + return (pte_t *)__get_free_page(GFP_PGTABLE & ~__GFP_ACCOUNT); >> } > > I think x86 was the only odd one out here, but you'll need to try again ... IIUC the user page table pages need __GFP_ACCOUNT not the kernel ones. Hence in the above function it clears out __GFP_ACCOUNT for kernel page table page allocations but where as by default it has got __GFP_ACCOUNT which would be used for user page tables. Instead we can make X86 user allocations add __GFP_ACCOUNT (like other archs) to generic GFP_PGTABLE when ever required.