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 B5440D3514A for ; Wed, 1 Apr 2026 07:25:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1757E6B0005; Wed, 1 Apr 2026 03:25:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 14D056B0088; Wed, 1 Apr 2026 03:25:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 062E86B0089; Wed, 1 Apr 2026 03:25:55 -0400 (EDT) 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 EAD0C6B0005 for ; Wed, 1 Apr 2026 03:25:54 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 96AA7140482 for ; Wed, 1 Apr 2026 07:25:54 +0000 (UTC) X-FDA: 84609152628.14.65EE7DD Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf30.hostedemail.com (Postfix) with ESMTP id B436E8000C for ; Wed, 1 Apr 2026 07:25:52 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=qX4jLvDr; spf=pass (imf30.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=1775028352; a=rsa-sha256; cv=none; b=6mKg4bWAbERntGMV9Xoqr0qjVvDSHrOwgzCs1zDd1CeBmuucazkHRj9dUMvo1k/nuiRDA3 DI5yGJWNMQyXPzpt0xj/ttZOx6znljL9xkUCPszGvt2fC1zCUdv4KdD5SPfB5xdN2htYHj 8swpVeSTwCy+xt9a+TA6/1KxNsLw+Xw= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1775028352; 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=KxqPiN/KwVdriFzVUgpAHYVxZpLTKWeNXC01oytRM8Q=; b=iHmTbqjPoI7yt69wj9qJv3wpiLk+gqhkfJC9kCtxCPheeZTs8bl2zPg168nDrf8EeZsT6U 3YdgnwOMmmurm1jS9GcSD5uyhdrkpWFpPmseQUbu5iq3U1hM/UcMgEkdfrc4rXZdsmKPIl 7sQCMxEAx+xlHp+PeTnJdpJwIl+Ckek= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=qX4jLvDr; spf=pass (imf30.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 (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id A07D540538; Wed, 1 Apr 2026 07:25:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 47795C4CEF7; Wed, 1 Apr 2026 07:25:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775028351; bh=/QUj0UX1GZ+e+AE52Ux3eyGjyUiHdeSeeqDFLv2q5Kg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=qX4jLvDrJmxSsLVwA3eo8uG050mP8XiWMMqN5k9R/l0hndwSrsxt7kibC03ueHnSH SIgUxoisUzv6UTOQsLTv1og/LOuM4Bwg81t+Mb4YddVnvmUwOn7kQDizdAKpbLtZ+u b7siJsnJBGsheCh3CJPTgE1SdK9ps2QtDP+6S5w5oYCB7wykuayD2NESYpbwswixpN XxXnknBzgbTfYtbX1DZCmuVnAYqOC8xpnYJb0Fp/GAUHyUBsLnakNyyA/vcAgLEsbv +3qd+oZyKZXG4NWJ9BbuUEBnfAZZpruYzSfqKShx1MV2WOsb/A4hYilAxBhjeVIPzu WtRTTtj5bEslw== Message-ID: Date: Wed, 1 Apr 2026 09:25:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/sparse: fix preinited section_mem_map clobbering on failure path To: Muchun Song Cc: Muchun Song , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Frank van der Linden , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260331113724.2080833-1-songmuchun@bytedance.com> <17246161-f314-45da-933a-770231ef2a49@kernel.org> <2183487D-0CED-4BEF-84D7-4439F3386584@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: <2183487D-0CED-4BEF-84D7-4439F3386584@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: B436E8000C X-Stat-Signature: rn47p4eu9pacmgg4958mhkudxe98n86p X-HE-Tag: 1775028352-310355 X-HE-Meta: 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 MvZjuWRw pYy1Si6WVQkXqObShJ/udQx7MjhOxvGhelR5wsPMcNT7GQgSBwUb7LwZJNOWc6Mk5Gve6Yb6QE2QxusgYj5mHvFMMcEFWhipIPGsTOETglej4QIq5dfBYwq40wL8iymQdHImylxqcxMwLrB9U0aT1hBlgxUoztS1Z+wJ9g7v19pmAcYRFUWI6UamNz6iVn6zAH7n2HsGVRKyBNoSewvg9wBVSp72TJZTaUPNTYdspMYLIBzmqus9T9G/j01ZRNjvEC6KCzdcQQlOlVv2mDr5uOYYXVeCtNfy/uOeRNLYQ9HpbFDwmFRLLZLNnfeCjj/UPV2HrPb71rvPVN3sOPWaTdZeFmdd0dwGT5r0jvQQFr09JlJpWDdETB/1eZWJnUtvvYewb Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/1/26 04:41, Muchun Song wrote: > > >> On Apr 1, 2026, at 04:42, David Hildenbrand (Arm) wrote: >> >> On 3/31/26 13:37, Muchun Song wrote: >>> sparse_init_nid() is careful to leave alone every section whose vmemmap >>> has already been set up by sparse_vmemmap_init_nid_early(); it only >>> clears section_mem_map for the rest: >>> >>> if (!preinited_vmemmap_section(ms)) >>> ms->section_mem_map = 0; >>> >>> A leftover line after that conditional block >>> >>> ms->section_mem_map = 0; >>> >>> was supposed to be deleted but was missed in the failure path, causing the >>> field to be overwritten for all sections when memory allocation fails, >>> effectively destroying the pre-initialization check. >>> >>> Drop the stray assignment so that preinited sections retain their >>> already valid state. >>> >>> Fixes: d65917c42373 ("mm/sparse: allow for alternate vmemmap section init at boot") >>> Signed-off-by: Muchun Song >>> --- >>> mm/sparse.c | 1 - >>> 1 file changed, 1 deletion(-) >>> >>> diff --git a/mm/sparse.c b/mm/sparse.c >>> index c2eb36bfb86d..3a14b733bf71 100644 >>> --- a/mm/sparse.c >>> +++ b/mm/sparse.c >>> @@ -584,7 +584,6 @@ static void __init sparse_init_nid(int nid, unsigned long pnum_begin, >>> ms = __nr_to_section(pnum); >>> if (!preinited_vmemmap_section(ms)) >>> ms->section_mem_map = 0; >>> - ms->section_mem_map = 0; >> >> >> Acked-by: David Hildenbrand (Arm) > > Thanks. > >> >> I have some cleanup patches lying around that cleanup that code heavily. >> I think I get rid of this questionable "failed to allocate" case entirely. > > It's truly a coincidence — I also have a piece of code locally > that does something similar. Since allocation failure would also > affect subsequent startup processes, I simply made it panic when > allocation fails. Don't use BUG_ON, use actual panic(). :) And yes, we should rip out that handling. -- Cheers, David