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b=jFf8rHCTH49nGr989S2AyPg+bXct/7w82abPtTPRwDc3uUFPasL/xrBSog/q65K89PIqTsJit3BGAmgyWysok7BlCG93o2jEWq0vghhGKyX0w9XaTib2k1kCMfAMt2KouknuytwcKOSEPVCr8lKB7C4zOhFDAcbj40LZQ72nhvo= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R321e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033032089153;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=26;SR=0;TI=SMTPD_---0XAhWCyU_1789038883; Received: from 30.74.144.116(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0XAhWCyU_1789038883 cluster:ay36) by smtp.aliyun-inc.com; Thu, 10 Sep 2026 19:14:43 +0800 Message-ID: <65bf1722-c1fd-452a-88c1-c030b042cfbc@linux.alibaba.com> Date: Thu, 10 Sep 2026 19:14:42 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 08/19] selftests/mm: add folio-order check for address ranges To: Kiryl Shutsemau Cc: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, rppt@kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, usama.anjum@arm.com, usama.arif@linux.dev, nico.pache@linux.dev, ziy@nvidia.com, baohua@kernel.org, dev.jain@arm.com, hughd@google.com, lance.yang@linux.dev, liam@infradead.org, mhocko@suse.com, ryan.roberts@arm.com, shuah@kernel.org, surenb@google.com, vbabka@kernel.org, agordeev@linux.ibm.com, jgg@ziepe.ca, leon@kernel.org, kernel-team@meta.com References: <20260908125105.1510704-1-kirill@shutemov.name> <20260908125105.1510704-9-kirill@shutemov.name> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 1A24A140002 X-Stat-Signature: mozaozxmcsn3177ib46w1gg5kqafxefm X-HE-Tag: 1789038891-754452 X-HE-Meta: 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 dDzt5yrQ Ij0l477ise8uvjgpFxh1h07bTFvFwepz3IPfebVaNSD15pvE+Q3SHgEytkha/oWERN+7EwMP8wo3560Xpzfrx4pzXY3mR1+x5RlmOb069yJHYQREw+uYxLdG0cATUMCpQ+umBoepbRODKC+XYLsDzu4ulXNSGNyj0zbrQDHqxj0pBvayJGq1XA61AFxzX8Pq82OBITneQWjSYOE4ggxibUya326sz5vNmVwgwfCgoRZxgvIhgOJL5d6W9ZTwF1tZHIqtO2ioUPs9ANdj8y9QEZnIYEQofltpc7WzcNp6piPZGMdwSkLzvsgw9PJA1kTGxdm1C7twkspdyPPhpc+7qq0UXzTl/b/g4rcUccsUZCbEneuOOnKL/YGUURXX965DVcifpRYUJeJ+zmNA5le1zS5OpXg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/10/26 6:45 PM, Kiryl Shutsemau wrote: > On Wed, Sep 09, 2026 at 06:01:13PM +0800, Baolin Wang wrote: >> >> >> On 9/8/26 8:50 PM, Kiryl Shutsemau wrote: >>> From: "Kiryl Shutsemau (Meta)" >>> >>> An mTHP collapse test needs to know that a range is backed by folios of the >>> target order, and that they sit where a collapse would put them. Nothing >>> answers that today: is_backed_by_folio() classifies the folio behind a >>> single page, and check_huge_anon() reads smaps AnonHugePages, which only >>> accounts PMD mappings. >> >> Have you checked check_large_folios() in vm_util.c? It seems to meet your >> requirements, or am I missing something? > > The changelog is out of date, sorry: since 6dedaf0d46a9 check_huge_anon() > counts mTHP folios through check_large_folios() rather than reading > smaps, and it is what check_huge() already uses for mthp_khugepaged. > > It could do this job too, called once per window. > > What is_range_backed_by_order() adds is alignment check: the folio has > to sit at the window start. And check_large_folios() reopens two fds per > per call which kinda wasteful. OK. But can we extend the check_huge_xxx() functions to meet your requirements, for example by adding a check_aligned_huge_xxx() that wraps the underlying implementation of check_large_folios()? I still find it confusing that khugepaged.c has two separate sets of functions for checking large folios. Also, Yeoreum has also extended check_large_folios() further[1]. [1] https://lore.kernel.org/all/20260907-fix_split-v5-2-822b810458bc@arm.com/