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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 292C9C43334 for ; Mon, 27 Jun 2022 06:18:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232422AbiF0GSt (ORCPT ); Mon, 27 Jun 2022 02:18:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53258 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232040AbiF0GSs (ORCPT ); Mon, 27 Jun 2022 02:18:48 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 438982713 for ; Sun, 26 Jun 2022 23:18:47 -0700 (PDT) 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 10B471758; Sun, 26 Jun 2022 23:18:47 -0700 (PDT) Received: from [10.162.42.6] (unknown [10.162.42.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B19AE3F5A1; Sun, 26 Jun 2022 23:18:43 -0700 (PDT) Message-ID: Date: Mon, 27 Jun 2022 11:48:40 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH] mm: hugetlb: kill set_huge_swap_pte_at() Content-Language: en-US To: Qi Zheng , mike.kravetz@oracle.com, songmuchun@bytedance.com, akpm@linux-foundation.org, catalin.marinas@arm.com, will@kernel.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20220626145717.53572-1-zhengqi.arch@bytedance.com> From: Anshuman Khandual In-Reply-To: <20220626145717.53572-1-zhengqi.arch@bytedance.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/26/22 20:27, Qi Zheng wrote: > The commit e5251fd43007 ("mm/hugetlb: introduce set_huge_swap_pte_at() > helper") add set_huge_swap_pte_at() to handle swap entries on > architectures that support hugepages consisting of contiguous ptes. > And currently the set_huge_swap_pte_at() is only overridden by arm64. > > The set_huge_swap_pte_at() provide a sz parameter to help determine > the number of entries to be updated. But in fact, all hugetlb swap > entries contain pfn information, so we can find the corresponding > folio through the pfn recorded in the swap entry, then the folio_size() > is the number of entries that need to be updated. > > And considering that users will easily cause bugs by ignoring the > difference between set_huge_swap_pte_at() and set_huge_pte_at(). > Let's handle swap entries in set_huge_pte_at() and remove the > set_huge_swap_pte_at(), then we can call set_huge_pte_at() > anywhere, which simplifies our coding. > > Signed-off-by: Qi Zheng > --- > arch/arm64/include/asm/hugetlb.h | 3 --- > arch/arm64/mm/hugetlbpage.c | 34 ++++++++++++++++---------------- > include/linux/hugetlb.h | 13 ------------ > mm/hugetlb.c | 8 +++----- > mm/rmap.c | 11 +++-------- > 5 files changed, 23 insertions(+), 46 deletions(-) > > diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h > index 1fd2846dbefe..d20f5da2d76f 100644 > --- a/arch/arm64/include/asm/hugetlb.h > +++ b/arch/arm64/include/asm/hugetlb.h > @@ -46,9 +46,6 @@ extern void huge_pte_clear(struct mm_struct *mm, unsigned long addr, > pte_t *ptep, unsigned long sz); > #define __HAVE_ARCH_HUGE_PTEP_GET > extern pte_t huge_ptep_get(pte_t *ptep); > -extern void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr, > - pte_t *ptep, pte_t pte, unsigned long sz); > -#define set_huge_swap_pte_at set_huge_swap_pte_at > > void __init arm64_hugetlb_cma_reserve(void); > > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c > index c9e076683e5d..58b89b9d13e0 100644 > --- a/arch/arm64/mm/hugetlbpage.c > +++ b/arch/arm64/mm/hugetlbpage.c > @@ -238,6 +238,13 @@ static void clear_flush(struct mm_struct *mm, > flush_tlb_range(&vma, saddr, addr); > } > > +static inline struct folio *hugetlb_swap_entry_to_folio(swp_entry_t entry) > +{ > + VM_BUG_ON(!is_migration_entry(entry) && !is_hwpoison_entry(entry)); > + > + return page_folio(pfn_to_page(swp_offset(entry))); > +} Extracting this huge page size from swap entry is an additional operation which will increase the over all cost for set_huge_swap_pte_at(). At present the size value is readily available near set_huge_swap_pte_at() call sites.