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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 689E8C4332F for ; Fri, 13 May 2022 11:03:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To: Subject:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ZitBZqrHKsjyBG232/8b3wNAoHRLEOtBkpylmeAeBVI=; b=RF3Q9++19mNqpu /mc9o4pLmxRsz+Xq9BrHsaLQg55OlsJeuPf5ZyqmlGYnro8XPq/a35YL4kACXVzOsEpny5wzVNaH2 QYtpL+DOoOpwoShmWuhi4gDvbfzM/0Q0i/ABwM4Jzxgja1iQxaXvk0Mmhp1J3ZTdGnw/UAWTk67dr iCkvBvOaQO3WYTA6Agzy8+WYrKj3s++5I3Jy2ODCmI99IebUTymZ6aKscoKNndqruW8mzxN2h8zql uA6eroXKtgsCaCYTINRNSEm91ip2F55G0y+In7g41K+bolaMvn2QA5sqcddS6Pa47Or6lxUF+WIwb FAC6YJIJxZEYxg7YI0XA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1npT4D-00FhDX-Ba; Fri, 13 May 2022 11:02:42 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1npT45-00FhBL-Lz for linux-arm-kernel@lists.infradead.org; Fri, 13 May 2022 11:02:36 +0000 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: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220513_040233_871860_28D1D051 X-CRM114-Status: GOOD ( 23.68 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel