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 128664A92ED; Tue, 13 Oct 2026 18:42:24 +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=1791916948; cv=none; b=AKVZYdDO/AnBxez6CsLhbzmfx09WkNe+kecC5rWjxbPjFATBOCTUI79G+4XKDVUhHxZlcYpb2k7eEx5rGirZL6MYfU8SEbM+1VqOAitVijEWzm3bQVvSql1V3V0Ay0BjKoNoMn47j+CPQhnD6gfiuVK/Cqm8exeoaNnAt8YC630= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791916948; c=relaxed/simple; bh=DoEd1I4VdjTi+cM8P8AT1zLGlcJcvJGNM3epjZG8BgY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=KzK1vVEXJ49RbYvU1pGh0nxUjMShaXKcNVIuHiEzLq6R7RrM5MKIFCvF57V7bvFmx44HkXDrTLWQIr2PumIjcg9gi+sU9Vhg2/4pihhayOcbqj/+IZ3g5bI3NwRva3UzxoQfulBNgVSAXH5b0HS62o4/Poz0elcEtie1u5QFSOo= 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=M1r64E7W; 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="M1r64E7W" 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 F3F4F1655; Tue, 13 Oct 2026 11:42:20 -0700 (PDT) Received: from [IPV6:2409:40f2:30f:5cfa:fb93:6d70:e88:a98a] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8ADB43F871; Tue, 13 Oct 2026 11:42:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1791916944; bh=DoEd1I4VdjTi+cM8P8AT1zLGlcJcvJGNM3epjZG8BgY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=M1r64E7W8Yo9f8lxK5X2h+mMTqT4jrETX2jPo0Yt6R+E+LBUIE4Zc4FnkFWQdTm/G 6UYhZiXhHwzpYPKTObb2a/RO1H19NmwRV0yPDFONUheHhkcWIyQ3ea/xEQMIRiknU0 +0zz1/bokqGGSeColpkd3gzN4ivrif6CK6rBiQyY= Message-ID: Date: Wed, 14 Oct 2026 00:12:08 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 2/3] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro To: Yeoreum Yun Cc: Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , Peter Xu , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Morton , David Hildenbrand , Shuah Khan , Jason Gunthorpe , Leon Romanovsky References: <20261013-fix_hpage_macro-v7-0-3d77129e0557@arm.com> <20261013-fix_hpage_macro-v7-2-3d77129e0557@arm.com> Content-Language: en-US From: Sarthak Sharma In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/13/26 7:41 PM, Yeoreum Yun wrote: >> Hi Yeoreum! >> >> On 10/13/26 4:07 PM, Yeoreum Yun wrote: >>> HPAGE_SIZE and HPAGE_SHIFT macro is written based on the 4KB PAGE_SIZE. >>> When this macro is used in some test, test result would be strange in >>> the system where PAGE_SIZE is more then 4KB. >>> >>> Here is the example with transhuge-stress test with 16KB PAGE_SIZE: >>> >>> transhuge-stress: allocate 61073 transhuge pages, using 122146 MiB virtual memory and 1908 MiB of ram >>> 3.292 s/loop, 0.054 ms/page, 37106.002 MiB/s 2566 succeed, 58507 failed, 2566 different pages >>> 0.591 s/loop, 0.010 ms/page, 206850.792 MiB/s 0 succeed, 61073 failed, 0 different pages >>> 0.527 s/loop, 0.009 ms/page, 231895.107 MiB/s 0 succeed, 61073 failed, 0 different pages >>> 0.527 s/loop, 0.009 ms/page, 231839.704 MiB/s 0 succeed, 61073 failed, 0 different pages >>> 0.528 s/loop, 0.009 ms/page, 231544.782 MiB/s 0 succeed, 61073 failed, 0 different pages >>> 0.528 s/loop, 0.009 ms/page, 231462.074 MiB/s 0 succeed, 61073 failed, 0 different pages >>> 0.527 s/loop, 0.009 ms/page, 231770.300 MiB/s 0 succeed, 61073 failed, 0 different pages >>> ... >>> ok 1 Completed >>> >>> Remove the HPAGE_SIZE and HPAGE_SHIFT macro and introduce pmd_pshift() >>> helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-existing >>> helper, pmd_psize(). >>> >>> Also, run the KSM_MERGE_TIME_HUGE_PAGES test with a size of 512 MiB, >>> which is the least common multiple of the PMD sizes for 4 KiB, 16 KiB, >>> and 64 KiB base pages. Since allocate_transhuge() allocates mappings in >>> PMD-sized units, the test may fail with the previous size of 100 MiB, >>> which is not a multiple of the PMD size when the base page size is >>> 16 KiB or 64 KiB. >>> >>> After this patch, output of transhuge-stress: >>> >>> transhuge-stress: allocate 3817 transhuge pages, using 122146 MiB virtual memory and 119 MiB of ram >>> 2.558 s/loop, 0.670 ms/page, 47755.759 MiB/s 2585 succeed, 1232 failed, 2585 different pages >>> 2.640 s/loop, 0.692 ms/page, 46268.432 MiB/s 2585 succeed, 1232 failed, 2585 different pages >>> 2.635 s/loop, 0.690 ms/page, 46360.298 MiB/s 2585 succeed, 1232 failed, 2585 different pages >>> 2.782 s/loop, 0.729 ms/page, 43899.795 MiB/s 2616 succeed, 1201 failed, 2616 different pages >>> 2.692 s/loop, 0.705 ms/page, 45380.876 MiB/s 2627 succeed, 1190 failed, 2627 different pages >>> 2.612 s/loop, 0.684 ms/page, 46765.812 MiB/s 2628 succeed, 1189 failed, 2628 different pages >>> 2.683 s/loop, 0.703 ms/page, 45520.990 MiB/s 2630 succeed, 1187 failed, 2630 different pages >>> 2.727 s/loop, 0.714 ms/page, 44789.321 MiB/s 2631 succeed, 1186 failed, 2631 different pages >>> ... >>> ok 1 Completed >>> >>> Suggested-by: Lorenzo Stoakes (ARM) >>> Signed-off-by: Yeoreum Yun >>> --- >>> tools/testing/selftests/mm/guard-regions.c | 10 +++++-- >>> tools/testing/selftests/mm/ksm_tests.c | 16 ++++++----- >>> tools/testing/selftests/mm/run_vmtests.sh | 4 +-- >>> tools/testing/selftests/mm/transhuge-stress.c | 25 +++++++++++------- >>> tools/testing/selftests/mm/vm_util.c | 38 +++++++++++++++++++++++---- >>> tools/testing/selftests/mm/vm_util.h | 9 +++---- >>> 6 files changed, 71 insertions(+), 31 deletions(-) >>> >>> diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c >>> index f7d53ea3c2527..02f69244f9a42 100644 >>> --- a/tools/testing/selftests/mm/guard-regions.c >>> +++ b/tools/testing/selftests/mm/guard-regions.c >>> @@ -2194,14 +2194,20 @@ TEST_F(guard_regions, pagemap_scan) >>> TEST_F(guard_regions, collapse) >>> { >>> const unsigned long page_size = self->page_size; >>> - const unsigned long size = 2 * HPAGE_SIZE; >>> - const unsigned long num_pages = size / page_size; >>> + const uint64_t hpage_size = pmd_psize(); >>> + unsigned long size, num_pages; >>> char *ptr; >>> int i; >>> >>> if (!thp_available()) >>> SKIP(return, "Transparent Hugepages not available\n"); >>> >>> + if (!hpage_size) >>> + ksft_exit_fail_msg("reading hpage_size failed\n"); >> >> I'm sorry for not catching this earlier, but I don't think calling a >> ksft_exit_fail_msg() for not being able to calculate PMD size is a good >> idea. Maybe call an ASSERT*() here, something like >> >> ASSERT_NE(hpage_size, 0); >> >> so that just this test fails, instead of the whole run exiting with a >> bail out? > > No. The failure would occur if open() or read() fails, and subsequent > attempts would likely fail for the same reason. I think I couldn't clearly explain my concern. Let me put it again, please let me know if I am missing something. I was mistaken, on checking I found that guard_regions runs each test in a separate child process. So calling ksft_exit_fail_msg() won't exit the whole test run. To reproduce the case, I bind mounted /dev/null over /sys/kernel/mm/transparent_hugepage/hpage_pmd_size in a QEMU so that pmd_psize() returns 0. Then on running ./guard_regions (your patches applied), I got this output (putting relevant section of that since the log is quite long): # RUN guard_regions.anon.collapse ... Bail out! reading hpage_size failed # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0 # collapse: Test failed # FAIL guard_regions.anon.collapse not ok 29 guard_regions.anon.collapse . . ok 58 guard_regions.shmem.pagemap_scan # RUN guard_regions.shmem.collapse ... Bail out! reading hpage_size failed # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0 # collapse: Test failed # FAIL guard_regions.shmem.collapse not ok 59 guard_regions.shmem.collapse . . # RUN guard_regions.file.collapse ... Bail out! reading hpage_size failed # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0 # collapse: Test failed # FAIL guard_regions.file.collapse not ok 89 guard_regions.file.collapse # RUN guard_regions.file.smaps ... # OK guard_regions.file.smaps ok 90 guard_regions.file.smaps # FAILED: 87 / 90 tests passed. # 19 skipped test(s) detected. Consider enabling relevant config options to improve coverage. # Totals: pass:68 fail:3 xfail:0 xpass:0 skip:19 error:0 which looks weird with all the bailouts. On the other hand, if we replace the ksft_exit_fail_msg() with ASSERT_NE(), here's the output we get: # RUN guard_regions.anon.collapse ... # guard-regions.c:2205:collapse:Expected hpage_size (0) != 0 (0) # collapse: Test terminated by assertion # FAIL guard_regions.anon.collapse not ok 29 guard_regions.anon.collapse . . ok 58 guard_regions.shmem.pagemap_scan # RUN guard_regions.shmem.collapse ... # guard-regions.c:2205:collapse:Expected hpage_size (0) != 0 (0) # collapse: Test terminated by assertion # FAIL guard_regions.shmem.collapse not ok 59 guard_regions.shmem.collapse . . # RUN guard_regions.file.collapse ... # guard-regions.c:2205:collapse:Expected hpage_size (0) != 0 (0) # collapse: Test terminated by assertion # FAIL guard_regions.file.collapse not ok 89 guard_regions.file.collapse # RUN guard_regions.file.smaps ... # OK guard_regions.file.smaps ok 90 guard_regions.file.smaps # FAILED: 87 / 90 tests passed. # 19 skipped test(s) detected. Consider enabling relevant config options to improve coverage. # Totals: pass:68 fail:3 xfail:0 xpass:0 skip:19 error:0 So the issue is not as severe as I'd thought. It can be argued that this is very less likely to happen. But yeah, I feel changing it would be better as it is more suitable with the ksefltest_harness and would give a cleaner TAP output incase this happens. Rest I leave it to you and other folks to decide whether this needs to be changed :).