From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CA9A6606A321 for ; Sat, 31 Oct 2026 09:29:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=gHRZmNCY Received: by kanga.kvack.org (Postfix) id BC64A6B05BC; Sat, 31 Oct 2026 05:29:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B9D546B05BD; Sat, 31 Oct 2026 05:29:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AB43C6B05BE; Sat, 31 Oct 2026 05:29:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 808916B05BC for ; Sat, 31 Oct 2026 05:29:12 -0400 (EDT) Received: from smtpin19.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 0FB5712069B for ; Sat, 31 Oct 2026 09:29:12 +0000 (UTC) X-FDA: 85382397744.19.8D7F099 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf21.hostedemail.com (Postfix) with ESMTP id 55E381C0005 for ; Sat, 31 Oct 2026 09:29:10 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=gHRZmNCY; spf=pass (imf21.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=1793438950; 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=ll2fis6PW3e6O4+ywq8trqmNgeraIhRzhSrv/X2z4g0=; b=lYhvJR2p2XiuwluwvJdGPaHXmuZQDtSM3KdnLLEu35lN2dLmEKnprKVvd5sUzu3F7fg21q 94IwHCpYyjp8Ua51EkoN05rjWugW//vgArYTlT3NewFQnHMig5I5nbtbxciY1v4GZ4+V/R +/ZC3tMn8YdSjby86+qvOwl+mFjxjMQ= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793438950; b=6s2UzC8NS4kpq4DeayGnuz5TZIeV8tqWAqAzPdLb09rkW0W5qo28gnAKQlz2FH4c0ZhAxf 2k/sQbuDGEcqIsAMT3NBqXsSFyl9FKCXG+bHyq/olLp54uiWpZy2B2jnwZvv0KRfROUe+O W4hg+9QlVw9vP2dNoEdWtS2hNVf6Vg4= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=gHRZmNCY; spf=pass (imf21.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 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id F02CD600D4; Sat, 31 Oct 2026 09:29:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ACA2A1F00919; Sat, 31 Oct 2026 09:29:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793438948; bh=ll2fis6PW3e6O4+ywq8trqmNgeraIhRzhSrv/X2z4g0=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=gHRZmNCYSYLpZ9UHoD4zM/HC7SGTVM0A+qag4isL8bPqhVyIKmMKxBwYQT/kurhLU YX4Im7ICJiVFbQdXjxUm1jGIpb9SOovzJ75QNt/SEGA901F1JcUW6APRiOnIjH/HCC +ttOQJloaaFWtPSM+g+SqBPso2zMPiqyjSHtv7cqV9Ikyax6g7vDG7OSYEatKBpZmA 1ZgClYcVbjTGH7ODF7ZiS7gVXb3tAV3KrkVcje7xbDH6dlhP5xEeUe9mkFlAR614yM cnOW377XQtEtbpWyRBM4/9L3pb7HUxd0TF+eAaVJCD/wx+3adlIO7y5POMyH/klW2s VEt7XUYwKd4VQ== Message-ID: <895a3483-c773-4d5d-9760-c526c6cfb922@kernel.org> Date: Sat, 31 Oct 2026 10:28:59 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm/memory-failure: fix folio refcount leak and min_order_for_split() locking To: Andrew Morton Cc: Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Miaohe Lin , Naoya Horiguchi , Wei Yang , Nico Pache , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Luis Chamberlain , Tal Zussman , Li Youhong , stable@vger.kernel.org References: <20261030-try_to_split_thp_page-v2-1-c957c9b42eab@kernel.org> <20261030163553.c5dec200dd39cec4695e545c@linux-foundation.org> 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: <20261030163553.c5dec200dd39cec4695e545c@linux-foundation.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 55E381C0005 X-Stat-Signature: 4kch435fsjam8seyba3upy8dro59x9us X-Rspam-User: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1793438950-861572 X-HE-Meta: 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 F7w87I2f +tIwajDuVG+80bPzpyBGaxVkUThkd6gs3iNgjRI8FjgUKq7vs0AabAPkl2tn85Zh1smv6D+PMeznLGPDr0U1DxkiybGs4bih8lCr7rMY0KuwBNkib1coVubiVhx5ZN9obna7QD42f5hmywaqtI1j9D2Evmwr5YMZalyZYR2WA+ZgTJNoFBr2YEqvkbX2qRZ0sMQJ003uAQamC1+7ZllGP1+YR7quLSf4IbCFHYU8Tigk0xytGNUp6BiA3oo8X0KWH2cVxA06PB2JAWq42U+0QlASqrYgrFj2FDEJi3zYEaNr+F0jabtV/DbDwgKT/Le8CppVgPrwZl5zP34DhipE3oiLgP7r/ARvnLbIjg6Y9tr+fbmrJ+6cs6a2d6qEOytTGhBkAjWwivSGq5fIp3re+cCpaX8hI88UCf77j1cKOdV1i6yE= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/31/26 00:35, Andrew Morton wrote: > On Fri, 30 Oct 2026 23:29:13 +0100 "David Hildenbrand (Arm)" wrote: > >> hwpoison code can end up calling min_order_for_split() without holding >> the folio lock. There isn't really something that would prevent >> concurrent folio split. Consequently folio->mapping can get set to >> NULL after checking for "!folio->mapping", and if the compiler >> reloads folio->mapping, mapping_min_folio_order() would try to >> dereference NULL. > > Bit confused here. Is it referring to folios which end up outside EOF > which split effectively truncates, or did it mean to say "truncate"? I think above should say "There isn't really something that would prevent concurrent truncation." > > If the former, how is split able to folio_ref_freeze() a folio which > hwpoison has grabbed a ref on? > > IOW, is the race against split, or against truncate? It's splitting (min_order_for_split() reading ->mapping) racing with truncate (changing ->mapping). Want to fix up the s/folio split/truncate/ when applying or want me to resend? Thanks¡ -- Cheers, David