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 909E6F99368 for ; Thu, 23 Apr 2026 10:38:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DEE2B6B0005; Thu, 23 Apr 2026 06:38:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DC7146B008A; Thu, 23 Apr 2026 06:38:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CDB376B008C; Thu, 23 Apr 2026 06:38:37 -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 BB3026B0005 for ; Thu, 23 Apr 2026 06:38:37 -0400 (EDT) Received: from smtpin24.hostedemail.com (lb01b-stub [10.200.18.250]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 6A2391C04BD for ; Thu, 23 Apr 2026 10:38:37 +0000 (UTC) X-FDA: 84689471874.24.F0F2134 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf01.hostedemail.com (Postfix) with ESMTP id 715AD4000C for ; Thu, 23 Apr 2026 10:38:35 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=NOGs+0Jr; spf=pass (imf01.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=1776940715; 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=haIdrYWGrTuwiLse2hZYYcuWW2obGUZovwL6KO1WjhQ=; b=1pqeDpOsIISM4r9l740jOcAhirU2EbMV406+NQ3gKR2+ujNB6y1OzNgv00A4wJ/iwBbSAM 4xzgDkSyLm8Sx7hVDIS+l8seHl5Ms93UCq1ag8U4mLK1aMITOKZWPytBEdhbNxM+ejV9uz aKtFThD+G10yCHjZWpnVmMxmeAOKP1Y= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=NOGs+0Jr; spf=pass (imf01.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=1776940715; a=rsa-sha256; cv=none; b=u8V/B/9rU/ODYo+U7YHpBZdNyl1rM4tPos9E0MYMbtGmlToZPsazclYHkpBx0oZKOyMVTo E/7vwQGnK0QGmQ45BdTyH9MrPxYCtWg1JgI9+FLQCQbGx0A/vQx/v5SyYApt/eD3qJLR8F KGImPVtuma6dNTQJ1heZ2ObiIUtpd6w= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 562DD40566; Thu, 23 Apr 2026 10:38:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 206FFC2BCAF; Thu, 23 Apr 2026 10:38:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776940714; bh=OykCGngjeVXxh+S5FhihKYrlA0mMJyXZVqRb3yjbltQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=NOGs+0JrJ4V2SyqOjrtFCQhLPr6YNzdn9bI3as6PXFB7UQwCHKiLnzRPHyEUcB7ZN VKGOTXW/gkIMWlDZFdEi6oECp+yHwo4lAx3NokhIMuokGolZjyGr/nsVX3mbl/27Vo v7/vhuCEqkUK7uPz7wPEiT6mcRIUBnH2DMkpiEu/tktjWePw9DsAs0KodWlI72iVDz H0ITnKBGxvzcxasSWRZcfAXV5DGRFsTtMbzeNb5VyCC7xt43PWdQ0Qj1iPKl7saBqy 3FJRdZzjsfdBx5KUS9/me1V0pBiumh481fCG5n7UpmfcuKvquCsHIESxS8bpeMWIdr KGrBrssiZK2cA== Message-ID: Date: Thu, 23 Apr 2026 12:38:27 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 v5 2/6] mm/memory_hotplug: Fix incorrect altmap passing in error path To: Muchun Song , Andrew Morton , Muchun Song , Oscar Salvador , Michael Ellerman , Madhavan Srinivasan Cc: Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Nicholas Piggin , Christophe Leroy , aneesh.kumar@linux.ibm.com, joao.m.martins@oracle.com, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20260423071911.1962859-1-songmuchun@bytedance.com> <20260423071911.1962859-3-songmuchun@bytedance.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: <20260423071911.1962859-3-songmuchun@bytedance.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: g3y9x6pg51rjeq6ayity1a17qxz5ui5n X-Rspamd-Queue-Id: 715AD4000C X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1776940715-184716 X-HE-Meta: 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 L6HOYMd/ T66Vls59wDtfKrVYNFbRciY+lXuejQEk3wfz8pOggo652PR3eNiNbf0qK4Dgfd2Nu+auWbbJvxn+jdMZL4IkPSH0eihIjxn5akRKZKhSx1vup+jsyyeXr9Kul851fhxfz0LeU4DMbbJQ+iZsJ9V7yPHd2qdomwIubxehcz2mdw6jeiCZ1QQYHXkD9AxTPrmXtdmz093EdF9adb25dBNuogw/ZlefQ8SIxzgIfzz5KJk4TQ47Ih6AllsF2WRIHcHjxQIudXMO+o5VNhlBT+/tTIY4yn0Yema7MfHWx0VBhB0AMybcXeaXhjQhLBp4kgXzIhWzX9VT5cs6WSEpMqWrw25WwW5z4a/ZdVVLa Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/23/26 09:19, Muchun Song wrote: > In create_altmaps_and_memory_blocks(), when arch_add_memory() succeeds > with memmap_on_memory enabled, the vmemmap pages are allocated from > params.altmap. If create_memory_block_devices() subsequently fails, the > error path calls arch_remove_memory() with a NULL altmap instead of > params.altmap. > > This is a bug that could lead to memory corruption. Since altmap is > NULL, vmemmap_free() falls back to freeing the vmemmap pages into the > system buddy allocator via free_pages() instead of the altmap. > arch_remove_memory() then immediately destroys the physical linear > mapping for this memory. This injects unowned pages into the buddy > allocator, causing machine checks or memory corruption if the system > later attempts to allocate and use those freed pages. > > Fix this by passing params.altmap to arch_remove_memory() in the error > path. > > Fixes: 6b8f0798b85a ("mm/memory_hotplug: split memmap_on_memory requests across memblocks") > Signed-off-by: Muchun Song > --- > mm/memory_hotplug.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 2a943ec57c85..0bad2aed2bde 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1468,7 +1468,7 @@ static int create_altmaps_and_memory_blocks(int nid, struct memory_group *group, > ret = create_memory_block_devices(cur_start, memblock_size, nid, > params.altmap, group); > if (ret) { > - arch_remove_memory(cur_start, memblock_size, NULL); > + arch_remove_memory(cur_start, memblock_size, params.altmap); > kfree(params.altmap); > goto out; > } Yeah, that's nasty. We should CC stable. Acked-by: David Hildenbrand (Arm) Should we extend the safety checks we already have on the other path? diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 2a943ec57c85..1c304468af08 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1402,6 +1402,12 @@ bool mhp_supports_memmap_on_memory(void) } EXPORT_SYMBOL_GPL(mhp_supports_memmap_on_memory); +static void altmap_free(struct vmemmap_altmap *altmap) +{ + WARN(altmap->alloc, "Altmap not fully unmapped"); + kfree(altmap); +} + static void remove_memory_blocks_and_altmaps(u64 start, u64 size) { unsigned long memblock_size = memory_block_size_bytes(); @@ -1426,10 +1432,7 @@ static void remove_memory_blocks_and_altmaps(u64 start, u64 size) remove_memory_block_devices(cur_start, memblock_size); arch_remove_memory(cur_start, memblock_size, altmap); - - /* Verify that all vmemmap pages have actually been freed. */ - WARN(altmap->alloc, "Altmap not fully unmapped"); - kfree(altmap); + altmap_free(altmap); } } @@ -1460,7 +1463,7 @@ static int create_altmaps_and_memory_blocks(int nid, struct memory_group *group, /* call arch's memory hotadd */ ret = arch_add_memory(nid, cur_start, memblock_size, ¶ms); if (ret < 0) { - kfree(params.altmap); + altmap_free(params.altmap); goto out; } @@ -1469,13 +1472,12 @@ static int create_altmaps_and_memory_blocks(int nid, struct memory_group *group, params.altmap, group); if (ret) { arch_remove_memory(cur_start, memblock_size, NULL); - kfree(params.altmap); + altmap_free(params.altmap); goto out; } } return 0; -out: if (ret && cur_start != start) remove_memory_blocks_and_altmaps(start, cur_start - start); return ret; Maybe the helper should even go into altmap code? Not sure. -- Cheers, David