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Howlett" , Linus Torvalds , linux-arm-kernel@axis.com, linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org, linux-ide@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, Lorenzo Stoakes , Marco Elver , Marek Szyprowski , Michal Hocko , Muchun Song , netdev@vger.kernel.org, Oscar Salvador , Peter Xu , Robin Murphy , Suren Baghdasaryan , Tejun Heo , virtualization@lists.linux.dev, Vlastimil Babka , wireguard@lists.zx2c4.com, x86@kernel.org, Zi Yan References: <20250821200701.1329277-1-david@redhat.com> <20250821200701.1329277-10-david@redhat.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+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: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 71_uFTdeIxxtKOt0lZ_cpPQpKihWGg2bib2Ew1_u8Uo_1755886198 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 34F0C20007 X-Stat-Signature: ydbupyxh9d568m8z8t35oaak5j7h3bfn X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1755886201-155424 X-HE-Meta: U2FsdGVkX18xfBEcmCdXn0WAP5baZ5zd6Be2ldVc3JPePTXh89nqAKyCgqrV6k4ATNT5JXGGfAhfAZ8PHOUM3aP1HVxXcNl56DkuuAGR2EolxPgv8NC7cRiTbLlvAxFJWqtd3mbYOeByZDyDpToI32APgCuuBKwhDyiPYRpfmFBlOcxmF2dUww3EeSPZ8vC9TLyYwiTPA4U70hrgBPdjy98dBgHdH8PdyVUZZu4dKnyyT49j6e+z8oT4TnFlSSAflI8c9L+SofmY4YyKogrtxsg55i2EJiwV2qqrPZWffjiJXZo1zNdbrQZypJkx5rzhPm9c/p0aW2TA4ajHpaXTBKEcB6F7ZWEgM0NknJzP4EQW0ngCpzz3dUzVLaEBc0v60xbif5r6UFwy35SOqt66nesvm3POv/B9yb0v6FpXuABrlieQDn51ULxFP2XIOxxKKcWTI6KPGMXQtrNfQZneJGcsoduHJsg+6FufGMU2gJ3AM6rlqKj1Fbsda0NIJMe3yRm204SDLNdoDgNMQJdm+mSLU6BkcOdUiD5Su4PMg3amNIJRa0GhOqCX40ua4jBxUPTsO7bgGEgUB5ignU/DNS/06R5H9K0vsNFQK+4ClBkACNYYjn6TFW5ENt6VnvprwjDsS9QKwD+L1HcZWNk3x82lo1h+x6kTa2Mut4GQJ5VdX5TadH1b4pqmhhEwBeatdU9eEdQgxv+83aJI2EB7hdbAG6DtGCGuhxIXcBWq23PAIOlBtljCr52vTiNM3IlU94DoWI7Y62gMnuYh2tqgd05l74QqX14B1vE8ax8MPIVwFbZTAqGAw4Hz4gadFfTSjxfm4sKMM9LHYdUGTX9ezNmdZ/xVRMh3E+WaTIY2BjCzeQCnCLIs2lWs5j+Iy4ZKedsJL0mJRSE0gjF8zIruzO0OpjEZBnTr5HxFzJXws8BP8e2tEFG2t9qRMEJr1B+0pzp809MrL+jOGLvEuCm NWgUi0xZ A14nCp7VCN5e50ms9NhDUQSreBqfjI4vHjd3OVAF1NwzSEB+jfaAEhTB0F5Wcp2Tz5c1wDdMXQDnjz4WmxI8uZFT3X3r3DNBJfOQRgmxqh6mmhMAa//xHEzxe3zMc5ZPib/muwOkweIQXMMYhdrxTcvO/CQWiyd1wLmOcKa88bIcRwaiyLIeFY147Dqd2Z0M57lLZhbi54brQet7ap32Di/zsZdovMV1E/dw4vVY9A2u2iqNo58DriGUmrHBGC6iAfoCkPprLXTGJmYmBVOj6EUjU2S9JZUOSH+9WvXPDRjumhXjG68GVFWHWEw+F0geKuUqNS8wxVcMW76UmA0ZaeVjx5Rud23zOc0FKqNmbqWuYKSSTshit+UUhIlxseBweCnrUguPR0FfrwWi1bGM0fv4MtelLuKzjTvB5l66zameMXCnbFjMhKHHgVNpXxWHfeA3GnMKgkuZrosN8817hqTv4LA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 22.08.25 17:27, Mike Rapoport wrote: > On Thu, Aug 21, 2025 at 10:06:35PM +0200, David Hildenbrand wrote: >> Grepping for "prep_compound_page" leaves on clueless how devdax gets its >> compound pages initialized. >> >> Let's add a comment that might help finding this open-coded >> prep_compound_page() initialization more easily. >> >> Further, let's be less smart about the ordering of initialization and just >> perform the prep_compound_head() call after all tail pages were >> initialized: just like prep_compound_page() does. >> >> No need for a lengthy comment then: again, just like prep_compound_page(). >> >> Note that prep_compound_head() already does initialize stuff in page[2] >> through prep_compound_head() that successive tail page initialization >> will overwrite: _deferred_list, and on 32bit _entire_mapcount and >> _pincount. Very likely 32bit does not apply, and likely nobody ever ends >> up testing whether the _deferred_list is empty. >> >> So it shouldn't be a fix at this point, but certainly something to clean >> up. >> >> Signed-off-by: David Hildenbrand >> --- >> mm/mm_init.c | 13 +++++-------- >> 1 file changed, 5 insertions(+), 8 deletions(-) >> >> diff --git a/mm/mm_init.c b/mm/mm_init.c >> index 5c21b3af216b2..708466c5b2cc9 100644 >> --- a/mm/mm_init.c >> +++ b/mm/mm_init.c >> @@ -1091,6 +1091,10 @@ static void __ref memmap_init_compound(struct page *head, >> unsigned long pfn, end_pfn = head_pfn + nr_pages; >> unsigned int order = pgmap->vmemmap_shift; >> >> + /* >> + * This is an open-coded prep_compound_page() whereby we avoid >> + * walking pages twice by initializing them in the same go. >> + */ > > While on it, can you also mention that prep_compound_page() is not used to > properly set page zone link? Sure, thanks! -- Cheers David / dhildenb