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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F1CE5CA5FCE for ; Thu, 1 Oct 2026 08:08:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EA0D56B008C; Thu, 1 Oct 2026 04:08:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E79AB6B0095; Thu, 1 Oct 2026 04:08:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D8D736B0098; Thu, 1 Oct 2026 04:08:19 -0400 (EDT) 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 B63E06B008C for ; Thu, 1 Oct 2026 04:08:19 -0400 (EDT) Received: from smtpin23.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 2545214032B for ; Thu, 1 Oct 2026 08:08:19 +0000 (UTC) X-FDA: 85273329918.23.8F49E65 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf04.hostedemail.com (Postfix) with ESMTP id 61D3B40002 for ; Thu, 1 Oct 2026 08:08:17 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=TTK7DYyu; spf=pass (imf04.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1790842097; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=JBoILZl5w3rVZdYCV2v/uH/WRs7MvT7FJjqh3dz2DgY=; b=0VSTeVbgmUh/DuC4ai2mBNGe6cfvevin35XkZ1GyrqyLBRI4l9q6h14crLwfmPaJuQDlqp VtnLqY8LUhWbJheOZ0PlqsaYs6JZ7Gg/YWMroxIUYuWyG1iqieZB34vwYAOpEVHqJv9Iq3 zOPJyUoqEp5uLNp/iJOhBx5B3s70Qn0= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=TTK7DYyu; spf=pass (imf04.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1790842097; b=H8J5nFBf0XOwEGGHf+DJGhEbwYhOl3LPmOa6Ag4XjGOB/SOCF1clqSCQ9IgpVn+e4g+TuP 5e/WtG0y1VE8pzEg4hFGuATPKPbb05YVnH4RD4rGJWBNVUyJBlYCcuer3vHJt/tZ7tz/RB P1Si4fKwaga32Z3J8LsMjIulpmyEJyE= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id CDD9960234; Thu, 1 Oct 2026 08:08:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8BE81F00898; Thu, 1 Oct 2026 08:08:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790842096; bh=JBoILZl5w3rVZdYCV2v/uH/WRs7MvT7FJjqh3dz2DgY=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=TTK7DYyuhN9N2otVMELrHbTGkXbrOThlT22Y7LYi0nOdcFMAlHlFk6f3pekWwcF7R ou7xnpphnEv8hHBv1eP0diT7ejGGq3gUWoBnD2ZO4xgfTQGPc8t0TrD+7YaPtapy/G 2nHyNzjqBSNXC2hDTgXkSTqNGvaPXRqQqixRcuN3U87nprDU9UmLKxhp2ygzs3NZfi 2QCiaeFC27NwpdxZueJwfbbPW3LSzAhaDRsU3tPPtFheq94+zDgiHdy0OeQgZCJMV1 HrBl7Rn2ZDXexNFUETf6cQRsddZEtyg8mtAnwIsKLjAtS3q5zNzvg7kSOGUEVb/6Q0 YNnzsEAGai/zw== Message-ID: <67034af3-9849-49ab-8904-6d661178222f@kernel.org> Date: Thu, 1 Oct 2026 10:08:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 08/13] mm/collapse: call collapse_file() from collapse_single_pmd() To: Kiryl Shutsemau , Andrew Morton , Lorenzo Stoakes , Zi Yan , Baolin Wang Cc: "Kiryl Shutsemau (Meta)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Jann Horn References: <20260928100630.21870-1-kirill@shutemov.name> <20260928100630.21870-9-kirill@shutemov.name> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260928100630.21870-9-kirill@shutemov.name> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 61D3B40002 X-Rspam-User: X-Stat-Signature: b8e33ewiyofqp17n9chojcd1ui4beoou X-HE-Tag: 1790842097-174358 X-HE-Meta: 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 pU/sCXAI 5ZStJR05djCLqPMrRoKh+hwBiirNo+2aw6FnTcaR6DBtIlBkbOOaLSqXg8TE41+to2VyJM4wgNG9nzpjwpHzkD4/J73kGl1a+hQou6DkhRQCv2G7YCr1fYak41zycujLUtp/UtNV12TGrmAf22P29fDBoJwdYqz3WFZLPsU3df9qK56iO5lGUd10fd/2Fk8p2zfUvYygloZsQyYu0a63GkKrNDf4Ph+qYZFCc85zbTyeoDoehAU8FN3buJOjj3N7SIs/8DK6uo6SzBy486bkQ1vWNeA7fDZEmnl7QVv9+QP+Ds8G8anHyRBrODaG9vmbDxGlogObuqJf/GkkZlGBDfOdkrTHI6oLpZBJiPLdl/VulW8M= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/28/26 12:06, Kiryl Shutsemau wrote: > From: "Kiryl Shutsemau (Meta)" > > collapse_scan_file() reads the page cache to decide whether a table is > worth collapsing and, when it is, calls collapse_file() itself. The > caller cannot get between the decision and the collapse. > > Move the collapse_file() call up into collapse_single_pmd(), so the scan > stops at the decision. > > Two things change with it. The writeback retry re-runs collapse_file()> alone instead of rescanning first; collapse_file() repeats the scan's > checks under the page cache lock anyway. That change wasn't actually required for "call collapse_file() from collapse_single_pmd()", right? You merely decided to move the retry label in the same patch. > And mm_khugepaged_scan_file > fires before the collapse, so for an accepted table its status reads > SCAN_SUCCEED; what the collapse made of the table is for > mm_khugepaged_collapse_file to report. Ack. > > Preparation for splitting a collapse into a scan under mmap_lock and a > run without it. The file scan has to stop where the anonymous one will. > > Assisted-by: LLM > Signed-off-by: Kiryl Shutsemau (Meta) > --- > mm/khugepaged.c | 21 +++++++++++++-------- > 1 file changed, 13 insertions(+), 8 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 60ec7e80d554..89a4c3f5a91c 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -2737,13 +2737,9 @@ static enum scan_result collapse_scan_file(struct mm_struct *mm, > else > cc->progress += HPAGE_PMD_NR; > > - if (result == SCAN_SUCCEED) { > - if (present < HPAGE_PMD_NR - max_ptes_none) { > - result = SCAN_EXCEED_NONE_PTE; > - count_vm_event(THP_SCAN_EXCEED_NONE_PTE); > - } else { > - result = collapse_file(mm, addr, file, start, cc); > - } > + if (result == SCAN_SUCCEED && present < HPAGE_PMD_NR - max_ptes_none) { > + result = SCAN_EXCEED_NONE_PTE; > + count_vm_event(THP_SCAN_EXCEED_NONE_PTE); > } > > trace_mm_khugepaged_scan_file(mm, failed_pfn, file, present, swap, result); > @@ -2774,8 +2770,16 @@ static enum scan_result collapse_single_pmd(unsigned long addr, > > mmap_read_unlock(mm); > *lock_dropped = true; > -retry: > + > + /* > + * SCAN_PTE_MAPPED_HUGEPAGE is work too: the page cache already holds > + * the PMD folio, and only the PTE table is left to retract. > + */ > result = collapse_scan_file(mm, addr, file, pgoff, cc); > + if (result != SCAN_SUCCEED) > + goto put; > +retry: > + result = collapse_file(mm, addr, file, pgoff, cc); > > /* Dirty pages are worth a writeback and one more try, if asked for */ > if (cc->policy.file_writeback_dirty && result == SCAN_PAGE_DIRTY_OR_WRITEBACK && > @@ -2787,6 +2791,7 @@ static enum scan_result collapse_single_pmd(unsigned long addr, > triggered_wb = true; > goto retry; > } > +put: > fput(file); > > if (result == SCAN_PTE_MAPPED_HUGEPAGE) { Acked-by: David Hildenbrand (Arm) -- Cheers, David