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([2620:10d:c092:500::6:98ea]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b79c3ac036sm18872226f8f.15.2025.08.05.05.13.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 05 Aug 2025 05:13:54 -0700 (PDT) Message-ID: <2c795230-5885-4a1a-a0f9-c8352b9e7738@gmail.com> Date: Tue, 5 Aug 2025 13:13:49 +0100 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 5/6] selftests: prctl: introduce tests for disabling THPs completely To: David Hildenbrand , Andrew Morton , linux-mm@kvack.org Cc: linux-fsdevel@vger.kernel.org, corbet@lwn.net, rppt@kernel.org, surenb@google.com, mhocko@suse.com, hannes@cmpxchg.org, baohua@kernel.org, shakeel.butt@linux.dev, riel@surriel.com, ziy@nvidia.com, laoar.shao@gmail.com, dev.jain@arm.com, baolin.wang@linux.alibaba.com, npache@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, vbabka@suse.cz, jannh@google.com, Arnd Bergmann , sj@kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@meta.com, Donet Tom References: <20250804154317.1648084-1-usamaarif642@gmail.com> <20250804154317.1648084-6-usamaarif642@gmail.com> Content-Language: en-US From: Usama Arif In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 05/08/2025 11:30, David Hildenbrand wrote: > On 04.08.25 17:40, Usama Arif wrote: >> The test will set the global system THP setting to never, madvise >> or always depending on the fixture variant and the 2M setting to >> inherit before it starts (and reset to original at teardown). >> >> This tests if the process can: >> - successfully set and get the policy to disable THPs completely. >> - never get a hugepage when the THPs are completely disabled >>    with the prctl, including with MADV_HUGE and MADV_COLLAPSE. >> - successfully reset the policy of the process. >> - after reset, only get hugepages with: >>    - MADV_COLLAPSE when policy is set to never. >>    - MADV_HUGE and MADV_COLLAPSE when policy is set to madvise. >>    - always when policy is set to "always". >> - repeat the above tests in a forked process to make sure >>    the policy is carried across forks. >> >> Signed-off-by: Usama Arif >> --- >>   tools/testing/selftests/mm/.gitignore         |   1 + >>   tools/testing/selftests/mm/Makefile           |   1 + >>   .../testing/selftests/mm/prctl_thp_disable.c  | 173 ++++++++++++++++++ >>   tools/testing/selftests/mm/thp_settings.c     |   9 +- >>   tools/testing/selftests/mm/thp_settings.h     |   1 + >>   5 files changed, 184 insertions(+), 1 deletion(-) >>   create mode 100644 tools/testing/selftests/mm/prctl_thp_disable.c >> >> diff --git a/tools/testing/selftests/mm/.gitignore b/tools/testing/selftests/mm/.gitignore >> index e7b23a8a05fe..eb023ea857b3 100644 >> --- a/tools/testing/selftests/mm/.gitignore >> +++ b/tools/testing/selftests/mm/.gitignore >> @@ -58,3 +58,4 @@ pkey_sighandler_tests_32 >>   pkey_sighandler_tests_64 >>   guard-regions >>   merge >> +prctl_thp_disable >> diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile >> index d13b3cef2a2b..2bb8d3ebc17c 100644 >> --- a/tools/testing/selftests/mm/Makefile >> +++ b/tools/testing/selftests/mm/Makefile >> @@ -86,6 +86,7 @@ TEST_GEN_FILES += on-fault-limit >>   TEST_GEN_FILES += pagemap_ioctl >>   TEST_GEN_FILES += pfnmap >>   TEST_GEN_FILES += process_madv >> +TEST_GEN_FILES += prctl_thp_disable >>   TEST_GEN_FILES += thuge-gen >>   TEST_GEN_FILES += transhuge-stress >>   TEST_GEN_FILES += uffd-stress >> diff --git a/tools/testing/selftests/mm/prctl_thp_disable.c b/tools/testing/selftests/mm/prctl_thp_disable.c >> new file mode 100644 >> index 000000000000..ef150180daf4 >> --- /dev/null >> +++ b/tools/testing/selftests/mm/prctl_thp_disable.c >> @@ -0,0 +1,173 @@ >> +// SPDX-License-Identifier: GPL-2.0 >> +/* >> + * Basic tests for PR_GET/SET_THP_DISABLE prctl calls >> + * >> + * Author(s): Usama Arif >> + */ >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> + >> +#include "../kselftest_harness.h" >> +#include "thp_settings.h" >> +#include "vm_util.h" >> + >> +static int sz2ord(size_t size, size_t pagesize) >> +{ >> +    return __builtin_ctzll(size / pagesize); >> +} > > Note: We have this helper duplicated elsewhere (e.g., cow.c). > > See [1] how we're going to clean it up. > > Not sure how to resolve this. Probably, which series lands first in mm-unstable should clean it up. > > I would assume that Donet's series would go in first, such that you can just reuse the helper from vm_utils.h > > [1] https://lkml.kernel.org/r/20250804090410.of5xwrlker665bdp@master > > > Nothing else jumped at me > > Acked-by: David Hildenbrand > Thanks! I will wait a few days and see if it has made it into mm-new and rebase and send the next revision.