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 D57C3FD376C for ; Wed, 25 Feb 2026 16:05:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 447056B009E; Wed, 25 Feb 2026 11:05:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3FA956B009F; Wed, 25 Feb 2026 11:05:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 306EC6B00A0; Wed, 25 Feb 2026 11:05:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 1AE1C6B009E for ; Wed, 25 Feb 2026 11:05:08 -0500 (EST) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id C18C31405FB for ; Wed, 25 Feb 2026 16:05:07 +0000 (UTC) X-FDA: 84483453054.25.A7E00D5 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf24.hostedemail.com (Postfix) with ESMTP id D667418000E for ; Wed, 25 Feb 2026 16:05:05 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=aJpCmMSi; spf=pass (imf24.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 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=1772035506; 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=a2j64OZq+XWnWM49sQ5sWsWYMhDm7zk27Ebe/2YgfW8=; b=KyPlqpWx2dlXHmq0YM2gzJR36n24XOcYeagJom+ilEevzh0PiC5qttzw8hvxz/MZRusJYw wqZY+8Y4kVapF3LFmLey8j56dHlhRfJT7eypnkQ1gDnC1lfeTVwi9VgJKIFS5+ej4JJzAl qvbGmfwbdBI3JJ/jd4LtJqd51CRQ06c= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=aJpCmMSi; spf=pass (imf24.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772035506; a=rsa-sha256; cv=none; b=3a8v76RVTZqoInAoHkByL5H4u7R7HOgXmSAVEW8SMCOo6An/iYIoeso/R2VrgP8PKseZgM gZQNAC9iw3eYM5PfvIYr98fQ0j70myA22n1ZogYsNS43hQtxkDs83eLNEcAX8PwHTBA6U3 3dRAohWntuPL1GWNIpBPKfeE6UuftEQ= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id A862A43A09; Wed, 25 Feb 2026 16:05:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC5A6C116D0; Wed, 25 Feb 2026 16:05:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772035504; bh=6cBj+Nps6gZCDh175QMBhnUiCqnkZzeVhurQ5HBT2ak=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=aJpCmMSiyPeO4MPY5gwI9uFlCabMc/1yNENpczauCzT0QwiuYQlJmIRQFOEpksinJ IvoneyPH9CZV8jeMETGLxPY89iABSsjKDa3flLHDjfsroYhyrPix91bAX/WAbzLgZM kd/O/VBGATz10mlXOwKx8sSTiuqp1XEHlFWQIgUqLTxKW35fJX+qnVR4wtPNr6zU1T o3lhqdb3nPgolh+cGBPibLhsl7wqcbCRNL1+HW516okEraPlfkklM/8/6QGpdSYPNi 4cojZMILi0iWPXYbLV7DoRvSBsdFPLT01awtP+wDmtI7vHJ+R5wGQBMgvVAlucJ1OQ fmDQeX1GnUEpA== Message-ID: <0d4f253f-6e92-4aec-9df1-e668b457d362@kernel.org> Date: Wed, 25 Feb 2026 17:04:59 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] Revert "ptdesc: remove references to folios from __pagetable_ctor() and pagetable_dtor()" To: Axel Rasmussen , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , "Matthew Wilcox (Oracle)" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260225002434.2953895-1-axelrasmussen@google.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: <20260225002434.2953895-1-axelrasmussen@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: D667418000E X-Stat-Signature: dosbh5hepfeyf6ktxy8k7o4iqba6fzzj X-HE-Tag: 1772035505-774607 X-HE-Meta: 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 aJjDmG/e Ide08CYgHfPtd7TpbZDO3UXF3aSWNZjT9DTCp1OvPkTRk5juRcT8jmGur/f2CB+B5VKUAJwefdkcPn1zTgtBql81CagifsO2NuEFuUXzMbAPvFGx7q3dl3pRLeRzXKfMi6UeAiN2RmatUcSXsVmfPNslTix+wy+U6WyEZ9Qvt0d8eMupQLuwTqdezjeuoGhYzCqHU713WM6okXPB95ttXdLBfeh/bWdq3Oomq3cPA6MGNEVZOMkD7RDQNM+n6VNs+juksIhkWYI+LOHeYGOhdqv00VdS2FJ+kbRo83XiSS5GQpEZL3yqSNylHSQKrEYUZuoU+TPBmRT02bstTGZw8/yqq1XlCPCRS/LJ2vyuDMasoN4PF/8VHQZV9I0pPN1e0/1eL Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2/25/26 01:24, Axel Rasmussen wrote: > This change swapped out mod_node_page_state for lruvec_stat_add_folio. > But, these two APIs are not interchangeable: the lruvec version also > increments memcg stats, in addition to "global" pgdat stats. > > So after this change, the "pagetables" memcg stat in memory.stat always > yields "0", which is a userspace visible regression. Argh, missed that these page tables are charged. > > I tried to look for a refactor where we add a variant of > lruvec_stat_mod_folio which takes a pgdat and a memcg instead of a > folio, to try to adhere to the spirit of the original patch. But at the > end of the day this just means we have to call > folio_memcg(ptdesc_folio(ptdesc)) anyway, which doesn't really > accomplish much. The goal of the original patch is obviously to get rid of any folio references in ptdesc code. But if these ptdesc are charged, then we'd also need long-term a ptdesc->memcg_data. For now we could still go through page->memcg_data, to avoid going through the folio. But that requires some work, so likely we should just directly enlighten ptdesc to have memcg_data. Agreed that, as a quick fix, reverting the commit might be best. But let's wait a bit whether Willy has a comment. > > This regression is visible in master as well as 6.18 stable, so CC > stable too. > > Fixes: f0c92726e89f ("ptdesc: remove references to folios from __pagetable_ctor() and pagetable_dtor()") > Cc: stable@vger.kernel.org > Signed-off-by: Axel Rasmussen > --- > include/linux/mm.h | 17 ++++++----------- > 1 file changed, 6 insertions(+), 11 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 5be3d8a8f806..abb4963c1f06 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -3514,26 +3514,21 @@ static inline bool ptlock_init(struct ptdesc *ptdesc) { return true; } > static inline void ptlock_free(struct ptdesc *ptdesc) {} > #endif /* defined(CONFIG_SPLIT_PTE_PTLOCKS) */ > > -static inline unsigned long ptdesc_nr_pages(const struct ptdesc *ptdesc) > -{ > - return compound_nr(ptdesc_page(ptdesc)); > -} > - > static inline void __pagetable_ctor(struct ptdesc *ptdesc) > { > - pg_data_t *pgdat = NODE_DATA(memdesc_nid(ptdesc->pt_flags)); > + struct folio *folio = ptdesc_folio(ptdesc); > > - __SetPageTable(ptdesc_page(ptdesc)); > - mod_node_page_state(pgdat, NR_PAGETABLE, ptdesc_nr_pages(ptdesc)); > + __folio_set_pgtable(folio); > + lruvec_stat_add_folio(folio, NR_PAGETABLE); > } > > static inline void pagetable_dtor(struct ptdesc *ptdesc) > { > - pg_data_t *pgdat = NODE_DATA(memdesc_nid(ptdesc->pt_flags)); > + struct folio *folio = ptdesc_folio(ptdesc); > > ptlock_free(ptdesc); > - __ClearPageTable(ptdesc_page(ptdesc)); > - mod_node_page_state(pgdat, NR_PAGETABLE, -ptdesc_nr_pages(ptdesc)); > + __folio_clear_pgtable(folio); > + lruvec_stat_sub_folio(folio, NR_PAGETABLE); > } > > static inline void pagetable_dtor_free(struct ptdesc *ptdesc) -- Cheers, David