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b=Fligvshlmzi5fvDbnF99CY+QS0zNJr0YRoT1Rvyq23btHmpA9DpsTFltcQxenPyTz K8SCuh3ou3Q8fRRc2kLbT+nQeQeKq+kbgZ/ZMsU4H7xWVk4zLk4ieHCW+YXRq7Q7QV uiZBkSp8OOSQU5QlRIx9nb5D4UzlAShyqVm4XL+YdhOisKv5B6AZsuW09zqzlYbpS2 MayogMBhAQEer50SpzOVY+ch9gQLCTlIRV5HZJS3F1qw7TVjgazK65luMcdmzL/SNi 4NM1YoHh/37D9Lbu5682PuKBfiU9+rsagDgRtXHxmgRclQAJgO38eU+z+DJHQm+/Cf 8s0nyRsMyu2Yg== Message-ID: <0cc263e5-9bdf-460c-956f-873c3285699e@kernel.org> Date: Mon, 9 Nov 2026 13:57:55 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/huge_memory: use folio_dup_file_rmap_pud() in copy_huge_pud() To: sashiko-reviews@lists.linux.dev, Konstantin Khorenko , Zi Yan , Andrew Morton , Lorenzo Stoakes , Alistair Popple , Dan Williams Cc: linux-mm@kvack.org, nvdimm@lists.linux.dev References: <20261106-khorenko-vstor-151183-copy_huge_pud-dup-rmap-v1-1-cf8ee4fafabb@virtuozzo.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-Spam-Status: No, score=-12.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam09 X-Stat-Signature: nkf31myw455a9sdwsf9om719z8nnkeqj X-Rspamd-Queue-Id: DBE631A000A X-Rspam-User: X-HE-Tag: 1794229080-623191 X-HE-Meta: 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 O/IPdwqR /4ucwwqkgc+izLDBlCplOTzOMRU3Jmm1J6+q729V2aivm8hduP5+tfk8MZpHpbBy/z+IsF38T7aFGM5Dyj7gDdjGjTOH0dhtKJPW9QQAeiP9ubJSkMNVHkVGcd6PrYi8PKb+TbWyauVICpFmCOitS4cO3Ti0a2zVjxR70NvkgtDCyJr8c4Lg9iQA9NZXD0E/+VxNy9OJgKzE2eUbM1vdD/U3UjloxepkTLQwwm+0QN/4xP0eA07oK/Iky40Duw1JHSH5I7GtRgm54szFGaVgYBdxlDoB6pGCl7f3d/9JWtzRMKLQGLFVd0h1nlTAeNlgm0p0iWy5lWed9V8IOIdAFCw5gUFJEI5SbcBz3DnVq/+ZDfARted4G017guPw3DKF0KF2V Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/7/26 18:05, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found no new issues > in this patch, but noticed 1 related pre-existing issue it does not > introduce: > - [Medium] mm: hardware A/D bits discarded for PUD folios in > zap_huge_pud() [1] > -- > > commit a6bb79712598f2da7fdcc94c9b1b5f8b9aad8851 > Author: Konstantin Khorenko > > mm/huge_memory: use folio_dup_file_rmap_pud() in copy_huge_pud() > > This commit adds folio_dup_file_rmap_pud() to duplicate file rmap mapcounts > at the PUD level and uses it in copy_huge_pud() instead of > folio_add_file_rmap_pud(). > >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index d0e19d9e6b651..13caf81cb51af 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -2100,7 +2100,7 @@ int copy_huge_pud(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma >> * TODO: once we support anonymous pages, use >> * folio_try_dup_anon_rmap_*() and split if duplicating fails. >> */ >> - folio_add_file_rmap_pud(folio, page, dst_vma); >> + folio_dup_file_rmap_pud(folio, page, dst_vma); >> add_mm_counter(dst_mm, mm_counter_file(folio), HPAGE_PUD_NR); >> } > > [Severity: Medium] > This problem wasn't introduced by this patch, but does zap_huge_pud() > discard hardware accessed and dirty bits on the PUD folio [1]? > > mm/huge_memory.c:zap_huge_pud() { > ... > orig_pud = pudp_huge_get_and_clear_full(vma, addr, pud, tlb->fullmm); > ... > } else { > ... > page = pud_page(orig_pud); > folio = page_folio(page); > folio_remove_rmap_pud(folio, page, vma); > add_mm_counter(tlb->mm, mm_counter_file(folio), -HPAGE_PUD_NR); > ... > } > > Unlike zap_huge_pmd(), which checks the cleared entry and calls > folio_mark_accessed() and folio_mark_dirty(), zap_huge_pud() removes the > PUD rmap without propagating the young and dirty bits from orig_pud to the > folio. When unmapping a refcounted Device DAX PUD mapping, those hardware > A/D bits are lost, leaving the folio with stale access and dirty state. Probably not that relevant for fsdax, which is the only one supporting PUD THPs IIRC. -- Cheers, David