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b=bPUGyJe8jTsIlbF1xVTN5nX4l/yeQqqr6KUSLqOk5CwA8zaane6up/uXHy/A6ETFN 8GMdYQkC/9pvmhBP2zcSqtRvRTHOksDMwvx7gtNR3V/dSa5XbcrFjusMb5bbHlPAqY FtbHm8MMjkmKP//Sey/LKddohMLPyRf4C7s+5IntPmGQ+G5m0rp18ZxLjCBmoTbsqX 6+sBf9cofe3crMJ9E65oq/xyI3vlQ9WK8JdqiYXb7nE+wHWgrx4QfKgjh+C53e4xEw hQtZGro3VXx5kNioH4KUnh6d9IwsWjAmh0kD1m7YN8VI3LyBQcu4wnCHz5d6QOS+Jm 8qsGDtkKaCKQw== Message-ID: <45508a75-7549-40e2-a71a-807a824ea026@kernel.org> Date: Wed, 4 Nov 2026 10:11:14 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 43/47] mm/huge_memory: split huge PUDs when adjusting VMA boundaries To: Lance Yang Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, ljs@kernel.org, kasong@tencent.com, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, baoquan.he@linux.dev, baolin.wang@linux.alibaba.com, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, kees@kernel.org, peterz@infradead.org, jannh@google.com, pfalcato@suse.de, hughd@google.com, pasha.tatashin@soleen.com, pratyush@kernel.org, willy@infradead.org, jack@suse.cz, ziy@nvidia.com, riel@surriel.com, harry@kernel.org, apopple@nvidia.com, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, usama.arif@linux.dev, kas@kernel.org, matthew.brost@intel.com, jhubbard@nvidia.com, peterx@redhat.com, will@kernel.org, aneesh.kumar@kernel.org, npiggin@gmail.com, osalvador@suse.de, minchan@kernel.org, muchun.song@linux.dev, xu.xin@linux.dev, chengming.zhou@linux.dev, chrisl@kernel.org, shikemeng@huaweicloud.com, nphamcs@gmail.com, youngjun.park@lge.com, gourry@gourry.net, joshua.hahnjy@gmail.com, rakie.kim@sk.com, ying.huang@linux.alibaba.com, jgg@ziepe.ca, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, stable@vger.kernel.org, usama.anjum@arm.com References: <20261031-fixes_core-v3-43-d6437171ecc3@kernel.org> <20261104031245.9524-1-lance.yang@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Stat-Signature: tfdjnt6a1g97ze56f71mu6o5bh3f3u76 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_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspamd-Queue-Id: EE64A140005 X-Rspam-User: X-HE-Tag: 1793783492-137734 X-HE-Meta: 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 ltd5J8Ml IpcPgklm4co7zpkw/jAHEJpE2eWYheWFwqvjBEN7d8BDCruEusCQg5zW6ql7DgUu73bryt0mVCEPvaeY5W6Cyf4F16DNPodYyqfROXj/Vuvi8ePHRo8Yj0v9qtdlnWNDJPrVMM8ULSurJuHRN/7+7psU8TXjrGZlLFZKpFDZdR98ZVjG2TGKM9d/ps4vunlYH0/tk4vU2VhzsOLRkcEqnT0+r/lKhTLTgLRClFV/HFQEgYzomEluLGds9IgVOsK1gT1dSSx0QKyxhFMNMl18DlJRNpsyz3z7VoR2MbMdaip8xc1gZ81waCJbpbkCQ7BNL8Cs5ev3vXHEawfDokohGOKmadQG8SUM2M9R6vCZI4LwsWg7HiuWalls3+C2vRO4lF2nUhZeSVzdi8ROSDKW5NIdoX1r15hR3lM02LcweWAoDWB7zjc7F6DjEnBMY3n2dXlVKCci12W/13nu2PYjeabnfBQ== 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 11/4/26 04:12, Lance Yang wrote: > > On Sat, Oct 31, 2026 at 10:40:12AM +0100, David Hildenbrand (Arm) wrote: >> PFN mappings such as VFIO PCI BAR mappings can use PUD leaves while >> allowing VMA splits at page granularity. However, vma_adjust_trans_huge() >> only handles PMDs. >> >> After faulting a writable PUD-sized VFIO BAR mapping, changing its first >> page to read-only with mprotect() makes the PMD walk treat the PUD leaf >> as a PMD table. Applying MADV_DONTFORK to the first PMD-sized chunk leaves >> the PUD spanning two VMAs: the PMD-aligned boundary skips splitting. >> >> Walk the page tables once at each adjusted boundary and split a huge >> PUD or PMD leaf as needed. Handle PUD leaves even when the boundary is >> PMD-aligned. >> >> Fixes: f9e54c3a2f5b7 ("vfio/pci: implement huge_fault support") >> Cc: stable@vger.kernel.org >> Tested-by: Muhammad Usama Anjum >> Reviewed-by: Kiryl Shutsemau (Meta) >> Signed-off-by: David Hildenbrand (Arm) >> --- > > Nice work! > > Reviewed-by: Lance Yang Thanks for the review! Please do keep reviewing, but note that more trailers (including this one) will likely not make it upstream as I am about to prepare the PR to get most of these things here upstream. -- Cheers, David