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 74B96C43458 for ; Mon, 13 Jul 2026 10:35:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7AC3A6B0005; Mon, 13 Jul 2026 06:34:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 784496B0088; Mon, 13 Jul 2026 06:34:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6731F6B008A; Mon, 13 Jul 2026 06:34:59 -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 4B11D6B0005 for ; Mon, 13 Jul 2026 06:34:59 -0400 (EDT) Received: from smtpin27.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id D5018140A7B for ; Mon, 13 Jul 2026 10:34:58 +0000 (UTC) X-FDA: 84983395476.27.5655902 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf28.hostedemail.com (Postfix) with ESMTP id 13843C0004 for ; Mon, 13 Jul 2026 10:34:56 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=hsRXNUQK; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf28.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1783938897; 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=8Gg6zcvzOEOlwfKtfjKwTjYa7q99CzNlGtktYSfy79w=; b=wYUUGELd9CuUV9j94MJPM8UDWEX7R3gI1BR6ohXQF5+yObizj0ybYwO6jzXP1nsavbHMHp YcgNJzpA8BDfbCxQos+7xXvsPqZNdVwT+mQ3N8g108waYFqGK7RJAUvPtF2wFhacvCrNiI 2H7Pj8H54W3hUfn/NwDKzh7Nl1fIn28= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=hsRXNUQK; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf28.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1783938897; b=wkDPlkPt8HD3RD7jR+Xk55q6Rp8NIGg/+2IH+mSkeqigY7cpsgCey4c0jh8hYZjN/v8UOB 6qufAzeTb1SIEj7DKkmCXpgtCK5qeOTGxMZdmLe1ICvCM/1NF7JVMK4PkcA+me5U7oc9pU MYFxiecCLGyiV0MqWQ52KwBAvlCW1L0= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 058F7413FF; Mon, 13 Jul 2026 10:34:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A04371F000E9; Mon, 13 Jul 2026 10:34:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783938895; bh=8Gg6zcvzOEOlwfKtfjKwTjYa7q99CzNlGtktYSfy79w=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=hsRXNUQKVx+rEC++ym4RrSK7/O9TMsKUyCkHp2Fg5BaNtVwEVYxvkkmgaR+Wguu09 AJ5HFafZ1LjP7/u3Fgc8gxcHzxLjfx4zXcIRFIYi6BvOLgrr07hM+Ta+QWh6fjcb+l wve84ooRTdU7Qzf6CjmIrgUpzVfPSdQlFAmkalqu1snmaYobmTcGZX9jmYQnjMRlTB 1E/twWmbcCOvsOE9bVKwCXN/0nk5W7IoMpjbhNabWDtFckxXER+Sjc9oGXAE2tnDWp 5Xm3brj5LRdA0NE1lkvKXyTB6+5JUsiNhwRkti1osmsmy3Plx6bClzAdgcXJdUtdTP zyQheO9XMUW3Q== Message-ID: Date: Mon, 13 Jul 2026 12:34:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/5] mm/rmap: Add try_to_unmap_hugetlb_one To: Dev Jain , akpm@linux-foundation.org, ljs@kernel.org, muchun.song@linux.dev, osalvador@suse.de Cc: riel@surriel.com, liam@infradead.org, vbabka@kernel.org, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com References: <20260710055915.638659-1-dev.jain@arm.com> <20260710055915.638659-3-dev.jain@arm.com> <49b408b9-6d10-4892-916f-ad8e7ef875e5@arm.com> 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: <49b408b9-6d10-4892-916f-ad8e7ef875e5@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: g11pktk71g4gdodx5ccemb4gok59gfff X-Rspamd-Queue-Id: 13843C0004 X-Rspamd-Server: rspam01 X-Rspam-User: X-HE-Tag: 1783938896-668314 X-HE-Meta: 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 Ey9Grtsd 9cm9woT4Rc9EG2hoeQVib7Pj9zBKPWnaP4Bvwy8Zb0edVp96aLaZgBdedd94ugk1hEFP44M3QoXTOjWaJ3egkSgadynjmi9cm0Ay0zgED5BqACNlMeX3wS8CZUxujO8xm+sXQ5FmZDF2ysOXAVXzmZ6w6RMJTF01wiY1IuqWIWhzroR2LXa6sr4qC79Ao1WjJbLwbnsF4IPjrM8iPbsBWKp0dg5zd2PIPbuu0sb5mkXyCn6qBAZSmTKQCsmjHyQjXUw0VuH4zYsiQIViK+U7NE0UUaFj77oNebMye5D7XVud+s+SmfBJ6te4CRyn+/IWhqmlloTaScRjQN882KitbUqZx23m59qFD+o+NLf+7sGTphFSm2ApTBS7xPlrjH4UI7Q6vo2pDsl+6XKI= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/10/26 15:16, Dev Jain wrote: > > > On 10/07/26 11:29 am, Dev Jain wrote: >> Simplify try_to_unmap_one() by separating the hugetlb parts into >> try_to_unmap_hugetlb_one(). >> >> To understand the correctness of the refactoring, the following points >> are noted: >> >> 1. try_to_unmap() is called for hugetlb folios only when they are >> hwpoisoned. >> >> 2. A hugetlb VMA cannot be mlocked. >> >> 3. page_vma_mapped_walk() returns at most one hugetlb mapping in a VMA, >> and that mapping points at the head PFN. >> >> 4. We won't ever process a softleaf entry that encodes a hugetlb folio; >> hugetlb folios are never swapped out, migration entries will be >> skipped (PVMW_MIGRATION not passed), and device-exclusive does not >> work for hugetlb. >> >> 5. The hwpoison entry is constructed from the poisoned folio, just as in >> the pre-refactor code. Any previous uffd-wp state is deliberately not >> preserved for the hwpoison entry. >> >> 6. TTU_HWPOISON is always present; for it to not be present, either the >> folio has to be in swapcache, or mapping_can_writeback() is true (see >> unmap_poisoned_folio), none of which is true for hugetlb folios. >> >> 7. Hugetlb uses separate counters from normal rss counters, therefore >> update_highwater_rss() need not be called. >> >> While at it: >> >> - Change VM_BUG_* to VM_WARN_*. >> >> - Do not declare variables which are only used once. >> >> - Constify some variables. >> >> - Add some more VM_WARN_* to assert some invariants. >> >> Except the above 4 points, no functional change intended. >> >> Suggested-by: David Hildenbrand (Arm) >> Acked-by: David Hildenbrand (Arm) >> Signed-off-by: Dev Jain >> --- > > Andrew, could you squash the following diff: > > diff --git a/mm/rmap.c b/mm/rmap.c > index cf02b315a2ead..b61051b879c4c 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -2229,8 +2229,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, > update_hiwater_rss(mm); > > /* > - * With TTU_HWPOISON, we only expect small folios or hugetlb > - * folios here for now. > + * With TTU_HWPOISON, we only expect small folios here. > */ > if (folio_test_hwpoison(folio) && (flags & TTU_HWPOISON)) { > pteval = swp_entry_to_pte(make_hwpoison_entry(subpage)); Note that the comment likely fits into a single line now. -- Cheers, David