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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Kevin Brodsky , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 3/4] kselftest: mm: integrate huge page checks Message-ID: References: <20260924-fix_split-v8-0-cba7359d882a@arm.com> <20260924-fix_split-v8-3-cba7359d882a@arm.com> <16f16e77-05ab-418e-ad06-8f48fb29375a@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <16f16e77-05ab-418e-ad06-8f48fb29375a@kernel.org> X-Rspam-User: X-Stat-Signature: ohki63yoma4rnzgiicsggot91f7gno17 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 5226B20010 X-HE-Tag: 1790676105-421587 X-HE-Meta: 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 bpEoSjHj f1GQjqB/0iqdwLll2Z6h0SF+19ncKuhSwKzR1Bo3YNH+kbNeu29V2fB1Ql7qkD0Xp3mJMO8AOGOWE2Ntem1ao/pDwzHlYhgqCR9UJ4uCl0+HWoOwSvUPBYQraGswIPtgh8TMltW7SJBD1hDQZ1lFtOwRnQUgyZ5Ua1s9BIf4GLeBirm11EMMBA32GAhGFEYfuGE3KBzMjzpA4x2HLnveRdb5idpJd87POkmfM3BRnpfyZYyAUB/7Yqq6s+6cIPNKmcdrfx/1UviIQ3yMdFvLtcOPvVNFpfKH/M46r5L/l2qEHtrKRqZ+eB2THqTNarIHfSqDWNycgljAGYW23RUkopPGopg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 29, 2026 at 10:07:37AM +0200, David Hildenbrand (Arm) wrote: > On 9/24/26 21:11, Yeoreum Yun wrote: > > check_large_folios() only checks for large folios without distinguishing > > between anonymous and file-backed huge pages. > > > > To add huge page type checking, integrate the huge page checks into > > __check_huge(): > > > > 1. If hpage_size == pmd_pagesize, check PAGE_IS_HUGE instead of using > > check_large_folios(), since only the mapping type matters. This > > identifies PMD-mapped huge pages. > > > > 2. Otherwise, use check_large_folios() to detect large folios. This > > covers mTHP cases. > > > > 3. Check the folio flags according to the huge page type. > > > > Suggested-by: David Hildenbrand (Arm) > > Suggested-by: Zi Yan > > Signed-off-by: Yeoreum Yun > > --- > > Instead of merging both things (detecting mapping vs. detecting anon vs. file), > could we simply perform the anon vs. file change separately? > > Doing another pagemap walk that focuses on that should end up with something > that is easier to read. Okay. I'll change like below in next-spin: -------&<------- @@ -411,57 +400,78 @@ static bool check_huge_type(uint64_t categories, enum check_huge_type type) return false; } -static bool __check_pmd_huge(void *addr, size_t len, int nr_hpages, - uint64_t hpage_size, enum check_huge_type type) +static bool __check_huge(void *addr, size_t len, int nr_hpages, + uint64_t hpage_size, enum check_huge_type type) { { - int pagemap_fd; + bool ret = false; + int pagemap_fd, kpageflags_fd; int nr_pmd_mappings = 0; + uint64_t pmd_pagesize, scan_mapping_size; uint64_t categories; + unsigned long pfn; + bool check_pmd_mapping, allow_nonpresent; char *start = addr; char *end = start + len; + pmd_pagesize = read_pmd_pagesize(); + if (!pmd_pagesize) + ksft_exit_fail_msg("reading PMD pagesize failed\n"); + + check_pmd_mapping = hpage_size == pmd_pagesize; + scan_mapping_size = (nr_hpages > 0) ? hpage_size : psize(); + /* Some mTHP tests check a partially populated PMD-sized range. */ + allow_nonpresent = (uint64_t)nr_hpages * hpage_size < len; + pagemap_fd = open(PAGEMAP_PATH, O_RDONLY); if (pagemap_fd < 0) ksft_exit_fail_perror("open pagemap"); - for (; start < end; start += hpage_size) { + kpageflags_fd = open(KPAGEFLAGS_PATH, O_RDONLY); + if (kpageflags_fd < 0) + ksft_exit_fail_perror("open kpageflags"); + + for (; start < end; start += scan_mapping_size) { categories = pagemap_scan_get_categories(pagemap_fd, start); - if (!(categories & PAGE_IS_HUGE)) + pfn = pagemap_get_pfn(pagemap_fd, start); + if (pfn == -1UL) { + if (!allow_nonpresent) + goto out; continue; - if (check_huge_type(categories, type)) + } + if (!check_huge_type(categories, type)) + goto out; + } + + if (!check_pmd_mapping) { + ret = check_large_folios(pagemap_fd, kpageflags_fd, + addr, len, nr_hpages, hpage_size); + goto out; + } + + for (start = addr; start < end; start += scan_mapping_size) { + categories = pagemap_scan_get_categories(pagemap_fd, start); + if (categories & PAGE_IS_HUGE) nr_pmd_mappings++; } - close(pagemap_fd); - return nr_hpages == nr_pmd_mappings; + if (nr_pmd_mappings != nr_hpages) + goto out; + ret = true; + +out: + close(pagemap_fd); + close(kpageflags_fd); + return ret; } -- Sincerely, Yeoreum Yun