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 E3F8AC433EF for ; Sat, 14 May 2022 02:58:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230216AbiENC6k (ORCPT ); Fri, 13 May 2022 22:58:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33176 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231440AbiENC5K (ORCPT ); Fri, 13 May 2022 22:57:10 -0400 Received: from out30-43.freemail.mail.aliyun.com (out30-43.freemail.mail.aliyun.com [115.124.30.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F2F6F2E5D02 for ; Fri, 13 May 2022 18:42:30 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R201e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0VD5LTZy_1652492545; Received: from 30.236.14.33(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VD5LTZy_1652492545) by smtp.aliyun-inc.com(127.0.0.1); Sat, 14 May 2022 09:42:26 +0800 Message-ID: Date: Sat, 14 May 2022 09:43:03 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH v2 2/2] arm64/hugetlb: Implement arm64 specific huge_ptep_get() To: Anshuman Khandual , 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: <15c2d16e-4071-677b-5ca5-3b66e6af59d5@arm.com> From: Baolin Wang In-Reply-To: <15c2d16e-4071-677b-5ca5-3b66e6af59d5@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 5/13/2022 7:03 PM, Anshuman Khandual 写道: > > > 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 Will fix. > >> 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. Sure. > >> >> 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. OK. > >> + >> + 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. Sure. > >> + >> + 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 Thanks for reviewing.