From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id D1D65449B01; Thu, 1 Oct 2026 13:52:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790862734; cv=none; b=DbFKZGnFqJOSY9D4R0QH3U/kYCUxLZGpJKA89ismj9XY2H+Zq64bbVO744SSzz3+pf5eLoiZFpwOB+32OpQb7cwlXlvIulxQNBtL35HsDziboPPxg/sLgYrcQqXgGKimGjjbnsX1zLusZBtSLaRYmQ6ft01wydwXTiU5GsW/IjM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790862734; c=relaxed/simple; bh=BFYsSQEEDW9ivKme2GW+ybv9NgRrwNxqnlj2UvnfFOY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MimD4An8XhbFqvXIDS0SKS8Tfnj9KAbTrA7QiimW/QUhTmFMKHMf4ZUblepAYm8lJpECYZ5VcGxXOJZ0h12XFHTQyjpgc/xWq6aW3DnbL+bY5uUFhy8q1v6Dje613eXIVaJ9ALIgbnWzOWg9iy1sma+AiZ1EQ5JNiEqJvIoff4g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=avLvr1eT; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="avLvr1eT" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 97F87497; Thu, 1 Oct 2026 06:52:07 -0700 (PDT) Received: from e129823.arm.com (e129823.arm.com [10.2.213.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 572643F86F; Thu, 1 Oct 2026 06:52:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790862731; bh=BFYsSQEEDW9ivKme2GW+ybv9NgRrwNxqnlj2UvnfFOY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=avLvr1eTGOHRMC4ainKq32M1Rv9qJhzcdp8ui1a6bT05iOwUQqOjMwV6ahWU8ss3M jdv6uqw6vGM52rUj4rOlVEcanprQmJ311rJcSCmQcbBoyOGAeEvbbSnKj2j+zpn10K uKUcHHRSK8QicsnORjwxzMBcM3eo2FWE3bVkDB3I= Date: Thu, 1 Oct 2026 14:52:06 +0100 From: Yeoreum Yun To: "David Hildenbrand (Arm)" Cc: Yeoreum Yun , Andrew Morton , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. 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> <3e03425b-7962-4c69-93aa-96168fd7168e@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3e03425b-7962-4c69-93aa-96168fd7168e@kernel.org> > On 9/29/26 12:01, Yeoreum Yun wrote: > > 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; > > } > > > > I'd leave existing __check_huge() mostly alone, and instead have an additional > function that checks the type. > > Essentially a __check_type() or sth that we run after the large folio / pmd check. So, You mean like this? -------&<------- -enum check_huge_type { - CHECK_HUGE_ANON, - CHECK_HUGE_FILE, +enum check_type { + CHECK_TYPE_ANON, + CHECK_TYPE_FILE, }; -static bool check_huge_type(uint64_t categories, enum check_huge_type type) +static bool __check_type(void *addr, size_t len, uint64_t page_size, + bool allow_nonpresent, enum check_type type) { - const bool file = categories & PAGE_IS_FILE; + bool ret = false; + int pagemap_fd, kpageflags_fd; + char *start = addr; + char *end = start + len; + uint64_t categories; + unsigned long pfn; + + pagemap_fd = open(PAGEMAP_PATH, O_RDONLY); + if (pagemap_fd < 0) + ksft_exit_fail_perror("open pagemap"); + + kpageflags_fd = open(KPAGEFLAGS_PATH, O_RDONLY); + if (kpageflags_fd < 0) + ksft_exit_fail_perror("open kpageflags"); - switch (type) { - case CHECK_HUGE_ANON: - return !file; - case CHECK_HUGE_FILE: - return file; + for (; start < end; start += page_size) { + categories = pagemap_scan_get_categories(pagemap_fd, start); + pfn = pagemap_get_pfn(pagemap_fd, start); + if (pfn == -1UL) { + if (!allow_nonpresent) + goto out; + continue; + } + + if ((type == CHECK_TYPE_FILE) != !!(categories & PAGE_IS_FILE)) + goto out; } - return false; + ret = true; + +out: + close(kpageflags_fd); + close(pagemap_fd); + return ret; } -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) { + bool ret = false; int pagemap_fd; int nr_pmd_mappings = 0; + uint64_t pmd_pagesize; uint64_t categories; char *start = addr; char *end = start + len; + pmd_pagesize = read_pmd_pagesize(); + if (!pmd_pagesize) + ksft_exit_fail_msg("reading PMD pagesize failed\n"); + pagemap_fd = open(PAGEMAP_PATH, O_RDONLY); if (pagemap_fd < 0) ksft_exit_fail_perror("open pagemap"); - for (; start < end; start += hpage_size) { + if (hpage_size != pmd_pagesize) { + ret = check_large_folios(addr, len, nr_hpages, hpage_size); + goto out; + } + + for (start = addr; start < end; start += hpage_size) { categories = pagemap_scan_get_categories(pagemap_fd, start); - if (!(categories & PAGE_IS_HUGE)) - continue; - if (check_huge_type(categories, type)) + 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); + return ret; } bool check_huge_anon(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) { - uint64_t pmd_pagesize = read_pmd_pagesize(); - - if (!pmd_pagesize) - ksft_exit_fail_msg("reading PMD pagesize failed\n"); + /* Some mTHP tests check a partially populated PMD-sized range. */ + const bool allow_nonpresent = (uint64_t)nr_hpages * hpage_size < len; + const uint64_t scan_mapping_size = (nr_hpages > 0) ? hpage_size : psize(); - if (hpage_size == pmd_pagesize) - return __check_pmd_huge(addr, len, nr_hpages, hpage_size, - CHECK_HUGE_ANON); + if (! __check_huge(addr, len, nr_hpages, hpage_size)) + return false; - return check_large_folios(addr, len, nr_hpages, hpage_size); + return __check_type(addr, len, scan_mapping_size, allow_nonpresent, + CHECK_TYPE_ANON); } bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) { - uint64_t pmd_pagesize = read_pmd_pagesize(); + /* Some mTHP tests check a partially populated PMD-sized range. */ + const bool allow_nonpresent = (uint64_t)nr_hpages * hpage_size < len; + const uint64_t scan_mapping_size = (nr_hpages > 0) ? hpage_size : psize(); - if (!pmd_pagesize) - ksft_exit_fail_msg("reading PMD pagesize failed\n"); - - if (hpage_size == pmd_pagesize) - return __check_pmd_huge(addr, len, nr_hpages, hpage_size, - CHECK_HUGE_FILE); + if (! __check_huge(addr, len, nr_hpages, hpage_size)) + return false; - return check_large_folios(addr, len, nr_hpages, hpage_size); + return __check_type(addr, len, scan_mapping_size, allow_nonpresent, + CHECK_TYPE_FILE); } -- Sincerely, Yeoreum Yun