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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id EDA7FC4167B for ; Tue, 5 Dec 2023 13:40:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7EC8A6B0093; Tue, 5 Dec 2023 08:40:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7756F6B0095; Tue, 5 Dec 2023 08:40:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5EF7F6B0096; Tue, 5 Dec 2023 08:40:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 448116B0093 for ; Tue, 5 Dec 2023 08:40:56 -0500 (EST) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 1BBC1A0105 for ; 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s=arc-20220608; d=hostedemail.com; t=1701783654; a=rsa-sha256; cv=none; b=tIGKe9AdKS0JAvfULyD8yI9PiiTE39ueGwnFcZuDL/3lZ/RGamVVt+6U2dhzkOQA3AARFn LMtsab9VEdJCaAmTSLafhXdQS22aas4I4EMpGl/GQ05J67vcH3BvbWWUmeYsnWFOwCDrOS ZyBoPqIHoLzxLHsHWWAQqrFWfM7DPCQ= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=none; spf=pass (imf07.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com 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 EB08A139F; Tue, 5 Dec 2023 05:41:39 -0800 (PST) Received: from [10.57.73.130] (unknown [10.57.73.130]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AA65A3F5A1; Tue, 5 Dec 2023 05:40:51 -0800 (PST) Message-ID: <183cf38c-476e-44c4-a8c7-22ed43122b41@arm.com> Date: Tue, 5 Dec 2023 13:40:51 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 34/39] mm/rmap: introduce folio_try_dup_anon_rmap_[pte|ptes|pmd]() Content-Language: en-GB To: David Hildenbrand , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , "Matthew Wilcox (Oracle)" , Hugh Dickins , Yin Fengwei , Mike Kravetz , Muchun Song , Peter Xu References: <20231204142146.91437-1-david@redhat.com> <20231204142146.91437-35-david@redhat.com> <88a341bf-0b6a-454a-aeb1-0699233eb37c@redhat.com> From: Ryan Roberts In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: 6uas8ndiqixd7g5as85w45zwqo9b1znt X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 4FD5340012 X-Rspam-User: X-HE-Tag: 1701783654-216501 X-HE-Meta: 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 U98XaUBf iq6EDOHWh3yz4KFumQL10EpyHUJv5DGSWMQSBTtjRk+I8Ptvb24g4k1gCPxFzbQ5WE1iZmZEMsZIRfJstL1fa45d9fZVUM1mES2xv+VAMwLAGk2DKGhp3850bEdaTi63r2fUX8S8JzthlVxG/xVOALwdBSbj2Fwutjc4BIn7YTjs0iL9KF+V2nIgK42rN3w3OdHi1YN+5pTiD2sKDKWtPuZwCcg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 05/12/2023 13:32, David Hildenbrand wrote: > On 05.12.23 14:17, David Hildenbrand wrote: >> On 05.12.23 14:12, Ryan Roberts wrote: >>> On 04/12/2023 14:21, David Hildenbrand wrote: >>>> The last user of page_needs_cow_for_dma() and __page_dup_rmap() are gone, >>>> remove them. >>>> >>>> Add folio_try_dup_anon_rmap_ptes() right away, we want to perform rmap >>>> baching during fork() soon. >>>> >>>> Signed-off-by: David Hildenbrand >>>> --- >>>>    include/linux/mm.h   |   6 -- >>>>    include/linux/rmap.h | 145 +++++++++++++++++++++++++++++-------------- >>>>    2 files changed, 100 insertions(+), 51 deletions(-) >>>> >>>> diff --git a/include/linux/mm.h b/include/linux/mm.h >>>> index 24c1c7c5a99c0..f7565b35ae931 100644 >>>> --- a/include/linux/mm.h >>>> +++ b/include/linux/mm.h >>>> @@ -1964,12 +1964,6 @@ static inline bool folio_needs_cow_for_dma(struct >>>> vm_area_struct *vma, >>>>        return folio_maybe_dma_pinned(folio); >>>>    } >>>>    -static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma, >>>> -                      struct page *page) >>>> -{ >>>> -    return folio_needs_cow_for_dma(vma, page_folio(page)); >>>> -} >>>> - >>>>    /** >>>>     * is_zero_page - Query if a page is a zero page >>>>     * @page: The page to query >>>> diff --git a/include/linux/rmap.h b/include/linux/rmap.h >>>> index 21d72cc602adc..84439f7720c62 100644 >>>> --- a/include/linux/rmap.h >>>> +++ b/include/linux/rmap.h >>>> @@ -354,68 +354,123 @@ static inline void folio_dup_file_rmap_pmd(struct >>>> folio *folio, >>>>    #endif >>>>    } >>>>    -static inline void __page_dup_rmap(struct page *page, bool compound) >>>> +static inline int __folio_try_dup_anon_rmap(struct folio *folio, >>> >>> __always_inline? >> >> Yes. >> >>> >>>> +        struct page *page, unsigned int nr_pages, >>>> +        struct vm_area_struct *src_vma, enum rmap_mode mode) >>>>    { >>>> -    VM_WARN_ON(folio_test_hugetlb(page_folio(page))); >>>> +    int i; >>>>    -    if (compound) { >>>> -        struct folio *folio = (struct folio *)page; >>>> +    VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); >>>>    -        VM_BUG_ON_PAGE(compound && !PageHead(page), page); >>>> -        atomic_inc(&folio->_entire_mapcount); >>>> -    } else { >>>> -        atomic_inc(&page->_mapcount); >>>> +    /* >>>> +     * No need to check+clear for already shared PTEs/PMDs of the folio. >>>> +     * This includes PTE mappings of (order-0) KSM folios. >>>> +     */ >>>> +    if (likely(mode == RMAP_MODE_PTE)) { >>> >>> Presumbly if __always_inline then the compiler will remove this if/else and just >>> keep the part indicated by mode? In which case "likely" is pretty useless? Same >>> for all similar sites in the other patches. >> >> Yes, also had this in mind. As long as we use __always_inline it >> shouldn't ever matter. > > It seems to be cleanest to just do: > > switch (mode) { > case RMAP_MODE_PTE: >     ... >     break; > case RMAP_MODE_PMD: >     ... >     break; > } > Agreed.