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 683F0CDB46F for ; Tue, 23 Jun 2026 11:48:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 496116B0099; Tue, 23 Jun 2026 07:48:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 446DA6B009B; Tue, 23 Jun 2026 07:48:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3362B6B009D; Tue, 23 Jun 2026 07:48:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 0C7E96B0099 for ; Tue, 23 Jun 2026 07:48:26 -0400 (EDT) Received: from smtpin01.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 7CEDD167024 for ; Tue, 23 Jun 2026 11:48:25 +0000 (UTC) X-FDA: 84911004570.01.01896FA Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf29.hostedemail.com (Postfix) with ESMTP id B1A5512000A for ; Tue, 23 Jun 2026 11:48:23 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Sgu2UXjg; spf=pass (imf29.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; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1782215303; b=zrd6uFPHVloAHsK+b0Kruzam3CrxIL0ZuXq2l/N/SBBrTIVQ51laKLeR8bmjulBAu+ziNF z7U8xemLXFbTWDb6hASp1F1zxPaklJaDZwrOdutrdikZryplm/lRboc699j4jS7bZlDZ1b T0aqEtktwP0lo8Wzmo3sPna/KBYQgFk= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1782215303; 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=OtjwWXEuZAsYDPcpleuNlTNndFnbrGXHnPOWcgGQAuQ=; b=T969s7Cy5iGxzPs6USp9pIQbLoX1XZFFPmj9ejWuOuyt3HaKP13WVqUS3HLosuS8Zy/4al qo1k3isrP4+btmq3e18NXD1xkrGiUSE1eOxHBa9QTaFxvkVqGViq3ATSiK8KiyP/O7ACj5 qjVZwEJkgOQsz+iwc3EFcMJ3XFhshnc= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Sgu2UXjg; spf=pass (imf29.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 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id E69F9441C5; Tue, 23 Jun 2026 11:48:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9061F1F000E9; Tue, 23 Jun 2026 11:48:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782215302; bh=OtjwWXEuZAsYDPcpleuNlTNndFnbrGXHnPOWcgGQAuQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Sgu2UXjgmvNoZiNkjzcPVn8oGkRUMO9moGfMrVyBk3H/WGLviFw+NBhtmjASYDxIh ZM14RIJKpQVaC/o3WPcHHvv1kKCWdT+Uw4oGJ+cNGurNhDjgtCOxS3Vo2HA1SzenjB gLKRQwnhvbjccM3DNkZdsOYNWyYaJNyGVLtNYEqXBN2USpcYHK7gRqc9tVs+RnvdNr Pu73Qk4/UP8tMmKJFwXMyjGI0/1iSutTqeT4v9jGCAut9ODJHZF3WSTPQgNbj71kgs zyIobycGLTz5v83JwlXWWUfxw/nphCJ7uR9n0mborOAxgiwFoY8R9G1OZ9vMYHFxMY HdZ4E9SSsu2jg== Message-ID: Date: Tue, 23 Jun 2026 13:48:17 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm: avoid KCSAN false positive in memdesc_nid() To: Hui Zhu , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Hui Zhu References: <20260623084432.701120-1-hui.zhu@linux.dev> 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: <20260623084432.701120-1-hui.zhu@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 9pksehgi1q8nkpuzyaarce58hnqthazh X-Rspam-User: X-Rspamd-Queue-Id: B1A5512000A X-Rspamd-Server: rspam02 X-HE-Tag: 1782215303-63618 X-HE-Meta: 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 Cc/PmHqk FB6YiQ+vWrYUw6mreik9MnZII8X3Uttd1sSdK1f4UegL7ylTr3vGZFx/x9FV7naDYYJIwnEe2LIp3oaWBBWOwYNUir8QhGSZU/0whoAuyAZIjPLkkeky9KY7Z3U2hWvsV30GjRFrSxun1v/c3V5ZG7TRcEYdSWht7d94BThDDR5teML/AU2JjwNtZcBhmrPjmfcm02psxmfFAJl8OIlg0EvFJjjeurOxewOKUsAc38d5quEjzqoupui7G4aNmPqo6MbtfV6kO4ftLTxRRJJHj1AoSgKnT6OkQosdcn9Z+tQ+qqPH/VQixP42WPPWneu2bvgjo3HhDP6f4csU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/23/26 10:44, Hui Zhu wrote: > From: Hui Zhu > > KCSAN reports a data race between page_to_nid()/folio_nid() reading > page->flags and folio_trylock()/folio_lock() concurrently doing > test_and_set_bit_lock(PG_locked, ...) on the same word, e.g.: > > BUG: KCSAN: data-race in __lruvec_stat_mod_folio / shmem_get_folio_gfp > > The node id occupies a fixed bit-range of page->flags that is set > once at page init and never modified afterwards, so it can never > overlap with the low PG_locked/PG_waiters bits touched by the folio > lock path. > > Use ASSERT_EXCLUSIVE_BITS() in memdesc_nid() to scope the exemption > to just the node-id bits, consistent with how memdesc_zonenum() > already handles the same class of race for the zone-id bits. > > Signed-off-by: Hui Zhu > --- Acked-by: David Hildenbrand (Arm) -- Cheers, David