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 3465FE77184 for ; Tue, 17 Dec 2024 17:14:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A5CB76B0088; Tue, 17 Dec 2024 12:14:41 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A335D6B0089; Tue, 17 Dec 2024 12:14:41 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 949A56B008A; Tue, 17 Dec 2024 12:14:41 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 78C386B0088 for ; Tue, 17 Dec 2024 12:14:41 -0500 (EST) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 2EB1A43B48 for ; 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s=arc-20220608; d=hostedemail.com; t=1734455645; a=rsa-sha256; cv=none; b=Vc3+DnjpPik5GYijfowKiGexruZtzOwJ2SI1PV0UGm1zHXBikuBzb0DWMQ887piVTmU7AF ABtfHwvPdAIN6LMDtPXIYqk9Z8YoCCA/Z9t2Q4hwZtqe2omsOM4gaWHOwgBYQtqRhAGtin eC7hZuycX56ddUuo+EIIOp2WEv9HjAk= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf08.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@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 7D1DDFEC; Tue, 17 Dec 2024 09:15:06 -0800 (PST) Received: from [10.57.91.184] (unknown [10.57.91.184]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 43E843F7B4; Tue, 17 Dec 2024 09:14:33 -0800 (PST) Message-ID: <011afa85-285d-4b26-9fac-e957f0812ebf@arm.com> Date: Tue, 17 Dec 2024 17:14:31 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 05/12] khugepaged: Generalize __collapse_huge_page_isolate() Content-Language: en-GB To: Dev Jain , Matthew Wilcox , g@casper.infradead.org Cc: akpm@linux-foundation.org, david@redhat.com, kirill.shutemov@linux.intel.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, cl@gentwo.org, vbabka@suse.cz, mhocko@suse.com, apopple@nvidia.com, dave.hansen@linux.intel.com, will@kernel.org, baohua@kernel.org, jack@suse.cz, srivatsa@csail.mit.edu, haowenchao22@gmail.com, hughd@google.com, aneesh.kumar@kernel.org, yang@os.amperecomputing.com, peterx@redhat.com, ioworker0@gmail.com, wangkefeng.wang@huawei.com, ziy@nvidia.com, jglisse@google.com, surenb@google.com, vishal.moola@gmail.com, zokeefe@google.com, zhengqi.arch@bytedance.com, jhubbard@nvidia.com, 21cnbao@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20241216165105.56185-1-dev.jain@arm.com> <20241216165105.56185-6-dev.jain@arm.com> <82c8712b-b7c3-4b58-8b29-dbc436d885be@arm.com> From: Ryan Roberts In-Reply-To: <82c8712b-b7c3-4b58-8b29-dbc436d885be@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: E981916001E X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: 76ay9iom5fujrc6ekfnwe84m1curubph X-HE-Tag: 1734455658-252784 X-HE-Meta: U2FsdGVkX1+FAjxG307TaE8SK9cIadOqkea2TRDvuTJPZgByCwhP/93xRvW6L3hkoQubV9XxVBMz2KfQv4+dkiHtY2PknuW2pecqehkxE5trQ49U6TKt3BA9QbVRKh4paGX9Y/fHVLoQJiJysiDJ5KvhM4ofWLhfWTittF2xwqFLtEv+3uynlBpWTfFgiikk1RiIABsQXrD2FlGwqZrka5wmX1MbquYN2ZzQ9EA4vNhUhCrGoreBzLCB1HjqFICkaSbOOM638CzuesgQ/cXPMCUMVQwDPie25j7fdarMUKT6NWY1m+r1QziWaFOGCacDwP1pVngLvE2pjzjc2mJmQyZk0mjagQCTYBw371RVga6/1B30eow+zlMX1bU2lw7zb7PEokeAmO/peEVMFdExLGprHy9H3VeZnv9H7UJVYmEAzUIwfVl4RaPlsGNZDlMMhgyNGpCKRLsdxOreO84kpB3CLIlRs3lgUckjNyRqJAvRfwaUd4uk0jAcShnNdR8vj0JBdkTYxWgyu19w40gvDkzjBEkxmdi7MCMDmgVH3wc0xXmr+3Fw6JH5hoR4y0+IIwNti3QHTVFuqF6p3reLDdZrNZqZ1dpBIiHZuif+qYImCM/hZM22zXiUNOrQHbmh1rQLA0GG2SILXunYgL27pIrFymyKq9gYl8KuhCslFrDzYIj23j9T2Qwf2rNxhn+8j7mBlMD7mH+op7Rg5pExfGgcPj9W5wEdQyyNGg/GHZUNf6s4HAA1/CBXkV26L03eV2Uyp6G9Iqv6x+ktSgurIYAWSILHWVaSd6XW9ZELLDO5jTq7lxTWjFWyLXk6iVDOEibwNVBWuGbsY3rXliXKPx8m76jJmLIi48QM373ddEQdEIST20dDrG5sjv7N94cgDDO2QfNE3dYP775bsISH7hCosqXngYUn5YnkkLTR+Y/GuU6TrdOXWsE4DYm23YRDextYf8Gf79th5YrIGEE yZ8Z3xQn dPFQj8Arv809+/75ue8MAptpHiRpMYs8nenZkTqYdjl9CEKXkftxmFguuLD9tsug0cJ47ZRhXdRk6r+CSpo9ubncMdQp+LYXPjOprqCgdC1KcEOSF120isRsLxdRbYwyTm4ZKpiHvsxe/UI5b3pbdNIaw6czqw+3A1oetY5GYdyFMfAkWauVdR5Gb8Zw4YGpCnyOPH28w3PBid0LhkML9F/S5ATqU12F5HK/dTGkFze53Wzd4W8leNOEUKXdCYkkFcwUQF0ilQbUtN4loE+yeo37HcvFrCrWdUyDCI8+CSyPM/rmmXl0+rcw1Z/VHeeH2xsS+R8sJxH9AJ5sgjFKDg/80E9mk/Mxsuh98aVtsJ/2zYC6ABfvN34iKr3o6mBC9AzUls/73lCqyHU6QjNMhokszeaoEBovQEEmv 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 17/12/2024 06:41, Dev Jain wrote: > > On 17/12/24 10:02 am, Matthew Wilcox wrote: >> On Mon, Dec 16, 2024 at 10:20:58PM +0530, Dev Jain wrote: >>>   { >>> -    struct page *page = NULL; >>> -    struct folio *folio = NULL; >>> -    pte_t *_pte; >>> +    unsigned int max_ptes_shared = khugepaged_max_ptes_shared >> >>> (HPAGE_PMD_ORDER - order); >>> +    unsigned int max_ptes_none = khugepaged_max_ptes_none >> >>> (HPAGE_PMD_ORDER - order); >>>       int none_or_zero = 0, shared = 0, result = SCAN_FAIL, referenced = 0; >>> +    struct folio *folio = NULL; >>> +    struct page *page = NULL; >> why are you moving variables around unnecessarily? > > In a previous work, I moved code around and David noted to arrange the declarations > in reverse Xmas tree order. I guess (?) that was not spoiling git history, so if > this feels like that, I will revert. > >> >>>       bool writable = false; >>> +    pte_t *_pte; >>>   -    for (_pte = pte; _pte < pte + HPAGE_PMD_NR; >>> + >>> +    for (_pte = pte; _pte < pte + (1UL << order); >> spurious blank line > > My bad > >> >> >> also you might first want to finish off the page->folio conversion in >> this function first; we have a vm_normal_folio() now. > > I did not add any code before we derive the folio...I'm sorry, I don't get what > you mean... > I think Matthew is suggesting helping out with the folio to page conversion work while you are working on this function. I think it would amount to a patch that does something like this: ----8<----- diff --git a/mm/khugepaged.c b/mm/khugepaged.c index ffc4d5aef991..d94e05754140 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -568,7 +568,6 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, unsigned int max_ptes_none = khugepaged_max_ptes_none >> (HPAGE_PMD_ORDER - order); int none_or_zero = 0, shared = 0, result = SCAN_FAIL, referenced = 0; struct folio *folio = NULL; - struct page *page = NULL; bool writable = false; pte_t *_pte; @@ -597,13 +596,12 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, result = SCAN_PTE_UFFD_WP; goto out; } - page = vm_normal_page(vma, address, pteval); - if (unlikely(!page) || unlikely(is_zone_device_page(page))) { + folio = vm_normal_folio(vma, address, pteval); + if (unlikely(!folio) || unlikely(folio_is_zone_device(folio))) { result = SCAN_PAGE_NULL; goto out; } - folio = page_folio(page); VM_BUG_ON_FOLIO(!folio_test_anon(folio), folio); if (order !=HPAGE_PMD_ORDER && folio_order(folio) >= order) { ----8<-----