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 74422F589AE for ; Thu, 23 Apr 2026 12:28:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DD17D6B0096; Thu, 23 Apr 2026 08:28:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DA8C06B00A2; Thu, 23 Apr 2026 08:28:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CBEC66B00A3; Thu, 23 Apr 2026 08:28:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id BB2E86B0096 for ; Thu, 23 Apr 2026 08:28:49 -0400 (EDT) Received: from smtpin09.hostedemail.com (lb01b-stub [10.200.18.250]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 3EEB887632 for ; Thu, 23 Apr 2026 12:28:49 +0000 (UTC) X-FDA: 84689749578.09.FB1538C Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf30.hostedemail.com (Postfix) with ESMTP id 7FD7080006 for ; Thu, 23 Apr 2026 12:28:47 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=PSM3c2kn; spf=pass (imf30.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=1776947327; 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=sG5ghfu2jFC4aldxD3kxvORSzXSDLLT86Yp0ZXVbsX0=; b=VzznP2nI8l/CFIhCAJ2MBBqLdX4zKPMAW1Mxdjhpr80qJR7cbehEZ1QLXAyc15ypSMgNsC 2zg+7GzVDwwaIyCrsjIDOEmHv1rSMLdI4djluQR3a1L5DHjPKiOyq5Xr600pKHZ6mJpkGg 9ihmmgZE1KhL1TGlJXGFzTMEJ+oSdLw= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=PSM3c2kn; spf=pass (imf30.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-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1776947327; a=rsa-sha256; cv=none; b=8EgBfwdtezASnSnBNRe8dxgjKBpFAY5YpNZaKSB9IktzZkZtYrjw21Br7uzjczglvUA6Gr xUP4KU9PU2EBvSkvx1nlsbOMwTm7Pfxai3Q8d691xK5LDMY+eCbcHIeTcGP6AdU2HCBc+o kVfmSiuEQ/HdiBqgYmhWutBE0v+u7do= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id CB5386014B; Thu, 23 Apr 2026 12:28:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D0860C2BCB3; Thu, 23 Apr 2026 12:28:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776947326; bh=WcCQRAneXN0yo79vQq3fLMIsGEAKpO1QE2YHg9kqD7s=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=PSM3c2knXTOwKhpHZ3jsKxgcWqqu7WR/VLqIlkdtlTrj2urvm5dfJhR4G4fEAwZjo kGacdtrfSH/1ysad2N/z3vSTegBdHt89r2CuMCwUMGEevOjAwgBojl4nZg33QoLFKH MSVdvQ7LDdF+39xjy/fe37m7drmazUXXFIGGOtwPDlyHpwEVSUlpTkDalc2bZBpk+L BWK2/7nhTK9cncPANlpebpoABAofbVKJkIPOPEQnibia1qF41hI0e1GhrPz4/BbnET o8jFO0uZ+eW+GQhpY/qxW0JptPeYcLYpCH40hCUZ/iBdMJoZJNfJlq8vwNZxetzkf7 EfSR6DU0Wg+eg== Message-ID: <25aac60c-8510-4d92-85f3-368cfe9d83ef@kernel.org> Date: Thu, 23 Apr 2026 14:28:39 +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 Cc: Muchun Song , Andrew Morton , Oscar Salvador , Michael Ellerman , Madhavan Srinivasan , 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: t16a9kb66neuoq1wh1dtwipitgsgieus X-Rspamd-Queue-Id: 7FD7080006 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1776947327-238373 X-HE-Meta: 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 FLGeit91 Z5CoXAeowgsPwD2CIdd//9Db7nJGHQJg96sUYQZPrEzJhvNCK7bF8yxldsqB/o19ASuY08gQmQTQZPtK23HZ6scdUxW4nnjg4x+DYV61cH7FABRAvp1zdNStY3d9XaapPvSOVq0jzKLm3xgL8bS4B+FZkRtlWki2O7P2Y4M07EV73qhFceZX4czs+rLKHfh4bpL/KxIye79DhGVg8qqhuPhxbcXUHpgulULEaDytqyeRNX2BPxZzFnNGz74++1TcKnJp8pvGHf8vnHbyM/RbHnEntGM8oyxIgM3se7c7rcSEAj+jN7T6/bmxBeNLfBP0l9xGNHD19cD/+7UJ1N5B/45ECoc146pUc/t9e Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/23/26 14:18, Muchun Song wrote: > > >> On Apr 23, 2026, at 18:38, David Hildenbrand (Arm) wrote: >> >> 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. > > Make sense. > >> >> Acked-by: David Hildenbrand (Arm) > > Thanks. > >> >> >> >> Should we extend the safety checks we already have on the other path? > > Better to have. > >> >> >> 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"); > > Should we change it to WARN_ONCE? Was debating with myself, and yes, I think so. > >> + 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. > > I think the current changes look great as they are. While I believe this is valuable > as a standalone cleanup, what do you think? Makes sense. Could you do me the favor and follow up with that, on top of the fixes? -- Cheers, David