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b=aTYH39GaDWfyNYxmlTbxqWG5yyl/nqPV8orp+2b+V1dTd5UU9hw2mYdeuoqocoKo4 2ZxZD4OIQRoYyofTL46wjmPS9b2d49+y9ZWwpH2TUFRgExrUqP2Con5OBQSuTa15UD lfIxlzBeSKSfZEunwQfD62A+Ngyyz1bPB1ZWYUpLMsuzyeQvNxox0qpa5YPF2rCEm0 OzddAttG1jvcOC6q9D1YwdpZ+EGScjoquQEbsfBKFE0aAx78QoJdd46OvGnFevl9a6 vji/MJDfY+01wWmnlG18ypeRv2Tx4pZAA1DcvgStvSq1iwUp2i1JH8hjXqyZqzyjTT ZVbX5VcHTW2Yg== Message-ID: Date: Wed, 13 May 2026 15:20:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drivers/base/memory: set mem->altmap after successful device registration From: "David Hildenbrand (Arm)" To: Georgi Djakov , akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-cxl@vger.kernel.org, osalvador@suse.de, gregkh@linuxfoundation.org, rafael@kernel.org, djakov@kernel.org References: <20260513130900.2204499-1-georgi.djakov@oss.qualcomm.com> 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-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 27AF74000F X-Rspam-User: X-Stat-Signature: r3xnscqg1yefezzgh8y7j3gkr4fzhohw X-HE-Tag: 1778678427-366634 X-HE-Meta: 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 +ZzfYsF/ suG5BINCMiqbzU48OP2zhqsiGnjJSq7/rZyV30OKuzzcUdQiI/NGdTLAxo+2+4Yg+/PuxssnvWv7g3SarBYrE8By9vGjZi88HFCSIWhCieJe79fp2OeD3S2euJArynl533ea/na7+9CY9xewtSINE/I5wyZq9aoy1wrUTBQFWTMDu8BUwYjWasWNs/Cv2DcfvUjFstWYzd7vP6q7Ib4YviWFX76IQnymuWo4yYNEyFhTeTeOKtTKcPaybeN4ucBHSVHPQzt6F2HkpjcDV9RcdzZK7ZQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/13/26 15:14, David Hildenbrand (Arm) wrote: > On 5/13/26 15:09, Georgi Djakov wrote: >> If __add_memory_block() fails at xa_store() (under memory pressure >> for example), device_unregister() is called, which eventually >> triggers memory_block_release() with mem->altmap still set, causing >> a WARN_ON(mem->altmap). >> >> WARNING: CPU: 1 PID: 76 at drivers/base/memory.c:96 memory_block_release+0x28/0x30 >> Call trace: >> memory_block_release+0x28/0x30 (P) >> kobject_put+0xc8/0x1bc >> device_unregister+0x2c/0x68 >> add_memory_block+0x1b4/0x214 >> create_memory_block_devices+0x9c/0xfc >> create_altmaps_and_memory_blocks+0x130/0x1cc >> add_memory_resource+0x10c/0x21c >> add_memory_driver_managed+0xb8/0xe8 >> virtio_mem_add_memory+0xa4/0x194 [virtio_mem] >> virtio_mem_sbm_plug_and_add_mb+0xc8/0x16c [virtio_mem] >> virtio_mem_run_wq+0xea8/0x1088 [virtio_mem] >> process_scheduled_works+0x18c/0x300 >> worker_thread+0x1dc/0x2b8 >> kthread+0x1ac/0x1f4 >> ret_from_fork+0x10/0x20 >> >> Fix this by delaying the assignment of mem->altmap until after >> __add_memory_block() has succeeded. > > Something does not add up here. How do you get an altmap with virtio-mem? That patch itself makes sense, but the callchain does not make sense. virtio_mem does not set MHP_MEMMAP_ON_MEMORY, so it should never reach create_altmaps_and_memory_blocks()? -- Cheers, David