From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BAE9924293C; Mon, 27 Apr 2026 09:28:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777282103; cv=none; b=ePgGdjefOOMXgbMOrEfgIihRUPHOnKzDazUbXARxV3G61iqOQ30QxIb2T3kNzZ1dNx2ueOnuh/ZIKtSVD06TIGNxp2ZNfTMVTJN3jTQ8j+2GmMNTkmMN9hKLaa79XUY2Ey4yY8udRqzp99ShzciwakWUXSpA61Ueup1rSia+6Us= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777282103; c=relaxed/simple; bh=38Eg7fzUhEHcKQxPhK//RD3lF1LtVHnHiWyYCaGxWi4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=C0L8FHWOGh7JbpPjdmoCDRtzmPTorEAUh5/ztGOFscgTPLa2hBnTKgErrjdbsPwtnQh4SdNrBgCb7aONsLKIE4fq2crkGljaBsQ90niDEvY7j6jaTYMzS4B0GojJw+l6D2uLFUT5s4q+7gURPYe4djjnQsHMzPPSdPQeoEaUKgk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=k9ko+X8h; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="k9ko+X8h" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DAD3C2BCB6; Mon, 27 Apr 2026 09:28:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777282103; bh=38Eg7fzUhEHcKQxPhK//RD3lF1LtVHnHiWyYCaGxWi4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=k9ko+X8hteZitT+P7Xd5MkF0CK4/Y98A6IupxRxKrxOYCU4MpLdgdWvbxewgoyW/R 1k09eUdB4tsx0fShHBjfIs+iLz/gFBgGAwso7o6XmdmGHpIMFNphG9JkDCr5LwiRlR hlZ2xuODo6d6T7TWh2xv1/ibvaJNSp0QzzZgp+CLhK7kD2flIQs8qXkdsB5gfhWJMw qJYH9lIhhvyMBqTeM71FRS9WBKGg4dam4/jbk+Y6UVYkbZhg6btTPaX+zgQ8zeTEBS DoHd8WdD6h6ijsbaFKBMFAFIN1DlHULxvWR+h27dR/yRKW7tylMEKmgOQPuh1/MoNW 0BriLFhOJAv1g== Message-ID: <572dc427-9598-4982-a015-d19904996dab@kernel.org> Date: Mon, 27 Apr 2026 11:28:15 +0200 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] drivers/base/memory: fix memory block reference leak in poison accounting To: Muchun Song , Miaohe Lin Cc: Muchun Song , Ying Huang , Dan Williams , Vishal Verma , Naoya Horiguchi , linux-mm@kvack.org, linux-cxl@vger.kernel.org, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Oscar Salvador , Andrew Morton , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich References: <20260426144447.817722-1-songmuchun@bytedance.com> <20260426144447.817722-2-songmuchun@bytedance.com> <7fe73023-1fd1-0c10-107e-5c0f47383453@huawei.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 On 4/27/26 11:16, Muchun Song wrote: > > >> On Apr 27, 2026, at 17:13, Miaohe Lin wrote: >> >> On 2026/4/26 22:44, Muchun Song wrote: >>> memblk_nr_poison_inc() and memblk_nr_poison_sub() look up a memory >>> block via find_memory_block_by_id(), which acquires a reference to the >>> memory block device. >>> >>> Both helpers use the returned memory block without dropping that >>> reference, leaking the device reference on each successful lookup. Drop >>> the reference after updating nr_hwpoison. >>> >>> Fixes: 5033091de814 ("mm/hwpoison: introduce per-memory_block hwpoison counter") >>> Cc: stable@vger.kernel.org >>> Signed-off-by: Muchun Song >> >> This patch looks good to me with one question below: >> >> Reviewed-by: Miaohe Lin > > Thanks. > >> >>> --- >>> drivers/base/memory.c | 8 ++++++-- >>> 1 file changed, 6 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/base/memory.c b/drivers/base/memory.c >>> index f806a683b767..6981b55d582a 100644 >>> --- a/drivers/base/memory.c >>> +++ b/drivers/base/memory.c >>> @@ -1230,8 +1230,10 @@ void memblk_nr_poison_inc(unsigned long pfn) >>> const unsigned long block_id = pfn_to_block_id(pfn); >>> struct memory_block *mem = find_memory_block_by_id(block_id); >>> >>> - if (mem) >>> + if (mem) { >>> atomic_long_inc(&mem->nr_hwpoison); >>> + put_device(&mem->dev); >> >> Comment above find_memory_block_by_id says it's called under device_hotplug_lock. >> >> /* >> * A reference for the returned memory block device is acquired. >> * >> * Called under device_hotplug_lock. >> */ >> struct memory_block *find_memory_block_by_id(unsigned long block_id) >> >> But device_hotplug_lock is missing here. Should we add it? > > Yes. Otherwise mem can be freed concurrently. I guess that is rather unlikely to happen, given that we just worked on online memory. But sure, if we can take that lock there easily, then let's do that. -- Cheers, David