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 6D7B3C433F5 for ; Fri, 13 May 2022 11:02:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379527AbiEMLCh (ORCPT ); Fri, 13 May 2022 07:02:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40580 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350219AbiEMLCe (ORCPT ); Fri, 13 May 2022 07:02:34 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 776D93A71A for ; Fri, 13 May 2022 04:02:32 -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 3B6A9143D; Fri, 13 May 2022 04:02:32 -0700 (PDT) Received: from [10.163.33.229] (unknown [10.163.33.229]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E4AFA3F5A1; Fri, 13 May 2022 04:02:25 -0700 (PDT) Message-ID: <15c2d16e-4071-677b-5ca5-3b66e6af59d5@arm.com> Date: Fri, 13 May 2022 16:33:39 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v2 2/2] arm64/hugetlb: Implement arm64 specific huge_ptep_get() Content-Language: en-US To: Baolin Wang , catalin.marinas@arm.com, will@kernel.org Cc: mike.kravetz@oracle.com, akpm@linux-foundation.org, songmuchun@bytedance.com, willy@infradead.org, christophe.leroy@csgroup.eu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: From: Anshuman Khandual In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/13/22 09:07, Baolin Wang wrote: > Now we use huge_ptep_get() to get the pte value of a hugetlb page, > however it will only return one specific pte value for the CONT-PTE > or CONT-PMD size hugetlb on ARM64 system, which can contain seravel A small nit. s/seravel/several > continuous pte or pmd entries with same page table attributes. And it > will not take into account the subpages' dirty or young bits of a > CONT-PTE/PMD size hugetlb page. > > So the huge_ptep_get() is inconsistent with huge_ptep_get_and_clear(), > which already takes account the dirty or young bits for any subpages > in this CONT-PTE/PMD size hugetlb [1]. Meanwhile we can miss dirty or > young flags statistics for hugetlb pages with current huge_ptep_get(), > such as the gather_hugetlb_stats() function, and CONT-PTE/PMD hugetlb > monitoring with DAMON. > > Thus define an ARM64 specific huge_ptep_get() implementation, that will > take into account any subpages' dirty or young bits for CONT-PTE/PMD size > hugetlb page, for those functions that want to check the dirty and young > flags of a hugetlb page. > > [1] https://lore.kernel.org/linux-mm/85bd80b4-b4fd-0d3f-a2e5-149559f2f387@oracle.com/ Might be worth mentioning that arm64 now enables __HAVE_ARCH_HUGE_PTEP_GET. > > Suggested-by: Muchun Song > Signed-off-by: Baolin Wang > Reviewed-by: Muchun Song > --- > arch/arm64/include/asm/hugetlb.h | 2 ++ > arch/arm64/mm/hugetlbpage.c | 24 ++++++++++++++++++++++++ > 2 files changed, 26 insertions(+) > > diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h > index 616b2ca..1fd2846 100644 > --- a/arch/arm64/include/asm/hugetlb.h > +++ b/arch/arm64/include/asm/hugetlb.h > @@ -44,6 +44,8 @@ extern pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, > #define __HAVE_ARCH_HUGE_PTE_CLEAR > 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 > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c > index 9553851..9a3f7f1 100644 > --- a/arch/arm64/mm/hugetlbpage.c > +++ b/arch/arm64/mm/hugetlbpage.c > @@ -158,6 +158,30 @@ static inline int num_contig_ptes(unsigned long size, size_t *pgsize) > return contig_ptes; > } > > +pte_t huge_ptep_get(pte_t *ptep) > +{ > + int ncontig, i; > + size_t pgsize; > + pte_t orig_pte = ptep_get(ptep); > + > + if (!pte_present(orig_pte) || !pte_cont(orig_pte)) > + return orig_pte; > + > + ncontig = num_contig_ptes(page_size(pte_page(orig_pte)), &pgsize); Hmm, I guess there is no better way of deriving page size here. Please drop the extra line here. > + > + for (i = 0; i < ncontig; i++, ptep++) { > + pte_t pte = ptep_get(ptep); > + > + if (pte_dirty(pte)) > + orig_pte = pte_mkdirty(orig_pte); > + > + if (pte_young(pte)) > + orig_pte = pte_mkyoung(orig_pte); > + } Please drop the extra line here. > + > + return orig_pte; > +} > + > /* > * Changing some bits of contiguous entries requires us to follow a > * Break-Before-Make approach, breaking the whole contiguous set Otherwise LGTM. With those small changes accommodated, Reviewed-by: Anshuman Khandual