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b=VPZtuL5j3tQOtekLQ7kOVDseIfHGH5e5b4IjDJWQWyfGuDyEHmFasxyAg4Znie6lF Cs5dkDB0jrbs5MFYwQbm3F0UpK684wLeGJ7s5CBFVSq1wSeXFnA6k+Gl+G7xtVmHun 2nxsLiVNyOsVv6jTwOohQOSd93cii87KioJLnuYwBjdKmHrHNj2AxORBcj0LwPbJsm cVmcA+2urdOJJjPIRDLgo5mMvdKgnkUy9gsWSXaNXDRIzBytPEeDhllvcYEjBy611V 4q+gzfRRr48ZCgjM3YHpKL8eEX43RKoz0P7AIhh5YOvIiXN531OhTGkvlkcG2aABiv QVLJhIVXZdzow== Message-ID: <0726ba54-a500-46a4-b42f-3e581da0f070@kernel.org> Date: Thu, 6 Aug 2026 12:50:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] mm/memory-failure: fix folio refcount leak and locking in soft/hard offline To: Andrew Morton , dayou5941@163.com Cc: linmiaohe@huawei.com, ljs@kernel.org, nao.horiguchi@gmail.com, linux-mm@kvack.org, ziy@nvidia.com, Li Youhong , Sashiko , stable@vger.kernel.org References: <20260806031958.677935-1-dayou5941@163.com> <20260805213415.002dc67766271d21c232910b@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: <20260805213415.002dc67766271d21c232910b@linux-foundation.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: y7q3u85yx5oatwaxwtga6xo3xs9fpgfk X-Rspamd-Queue-Id: 9175320006 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1786013429-822468 X-HE-Meta: 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 aJsm/QHW JLDnADNhX0ymr51jAfljeqNo3pgvcm9g6thWzkQHCaISIU4TVoPcriHFM30OQ2mpXd5MCnCPFK9LQ5MRFih6c0Y8Jp/peRRt7q4CKaUSQD9AhGfbaE38TveDi0sASnE4Q2PnjfEbDWcUyQx/+ck+3KAW7+KRcYMhPATNpztfiU5Z0UcI0xRtWzn0eal7nMDiM401tBpjWy+MPCF4UpWRWacGre7GCQu1C27pHiq6Df/7IOHODicePcxZXhpWhK++Zkf6Xz+IplztYi+Z/QoV497VEQrrz/n5m87aan7xEFgViTPje6LKMAv0kE1Ekvq+u2ScGy2c4DNBeKdhIbq8z8IrXhwcgksEeLmxfWyrYKGLRbLUSK5uLNV406+emN0mAzJJrytU6lCDjECamTbrAo7lwbRFH0kybHD1DednN6yWI/5po1jCHiRilqaCo3+Q92T8A Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/6/26 06:34, Andrew Morton wrote: > On Thu, 6 Aug 2026 11:19:58 +0800 dayou5941@163.com wrote: > >> From: Li Youhong >> >> The min_order_for_split() function accesses folio->mapping without proper >> synchronization. In memory_failure(), the folio lock is dropped before the >> call, and in soft_offline_in_use_page(), the lock is not held at all. This >> means that while min_order_for_split() is executing, the value of >> folio->mapping may be modified by a truncate or invalidate operation, >> leading to a torn read or use of a stale mapping value. >> >> Additionally, the soft_offline_in_use_page() path fails to release the >> folio reference taken by get_hwpoison_page() when new_order != 0, causing a >> reference leak. >> >> Fix these issues by: >> - Moving the split operation logic into the callers and holding the folio >> lock around min_order_for_split() and split_huge_page_to_order(). >> - Removing the try_to_split_thp_page() helper to simplify refcount >> handling. >> - Ensuring the folio reference is always dropped before returning on the >> soft-offline error path. >> >> This refactors the code to be more maintainable, fixes the locking issue >> reported by Sashiko, and also addresses the folio reference leak on the >> soft-offline error path. >> >> ... >> >> --- a/mm/memory-failure.c >> +++ b/mm/memory-failure.c >> static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn, >> struct address_space *mapping, pgoff_t index, int flags) >> { >> @@ -2440,7 +2420,6 @@ int memory_failure(unsigned long pfn, int flags) >> folio_unlock(folio); >> >> if (folio_test_large(folio)) { >> - const int new_order = min_order_for_split(folio); >> int err; >> >> /* >> @@ -2457,24 +2436,24 @@ int memory_failure(unsigned long pfn, int flags) >> * page is a valid handlable page. >> */ >> folio_set_has_hwpoisoned(folio); >> - err = try_to_split_thp_page(p, new_order, /* release= */ false); > > AI review asks (effectively) why the try_to_split_thp_page() return value > never gets used > > https://sashiko.dev/#/patchset/20260806031958.677935-1-dayou5941@163.com > No need for AI. Just from compiling: └ mm/memory-failure.c: In function ‘memory_failure’: mm/memory-failure.c:2492:21: warning: variable ‘err’ set but not used [-Wunused-but-set-variable] 2492 | int err; I'll send out a patch myself that already addresses everything raised in here without even me reading any of it. -- Cheers, David