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[2003:d8:2f2b:b200:607d:d3d2:3271:1be0]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-459d712c386sm81117925e9.23.2025.08.05.03.30.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 05 Aug 2025 03:30:25 -0700 (PDT) Message-ID: Date: Tue, 5 Aug 2025 12:30:23 +0200 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: Usama Arif , 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> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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 -- Cheers, David / dhildenb