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[2003:d8:2f2b:b200:607d:d3d2:3271:1be0]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-459db13fc9fsm75518385e9.7.2025.08.05.05.29.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 05 Aug 2025 05:29:19 -0700 (PDT) Message-ID: Date: Tue, 5 Aug 2025 14:29:17 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 6/6] selftests: prctl: introduce tests for disabling THPs except for madvise 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 References: <20250804154317.1648084-1-usamaarif642@gmail.com> <20250804154317.1648084-7-usamaarif642@gmail.com> <9bcb1dee-314e-4366-9bad-88a47d516c79@redhat.com> <5dc09930-e137-47ba-a98f-416d3319c8be@gmail.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: rz4b1rei7qyz3d5tmxska1s36isg4trt X-Rspamd-Queue-Id: A0F1C40009 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1754396964-314965 X-HE-Meta: U2FsdGVkX1+JK9EZB0UWVw/v6/M1GIxa/Ux90PFr/EhgrevtMJTYVjZ/5M0BoBbEjZp1/KTrVzzkBprKQ0r9EgudhtqpHBKWfIgFH/4QjCun7hB/R5tKW1hTsIBgYESpUDYWAkGvhvtgnk9fORGb3OBRZ7zATLG05Tt9SuK4hKpAdYDVe5l7Tr9SoitH8kZy35Eib5v8y/S94ALMU1RkepypnkTyK7mDC2DW4xBbtQT5bWFMs2MxC9s21JaptT6s5lRVwlMR/ZOgud08+8TcmZSu3NHY5+5UoKvGDZf2BwIFdB6vi0viHFbhcs7dGEu/kjLcWlPmwIod38kQzqUCmH1rZ6rLlLWvm7u+pOQesOstMf9kPXO7Ws84Zb1uc628jkKLrqHi3/bT5eVG0wrzDKlzkL81oWc96JHYsMEYXxy2PjvnWGqXf4n3brlWpTaQwVrWiIB3uCszXznn7yxHAUe983pwq0uoi7VCpAhQLX8fYQFqR46555w8XzhKMwwsCo7mCk7VG3BAWWrCetS5SPXlFuGKxW0wiWc4/GjXuMd+zjSqu6O64MClzRUysZu7Mks4zdRgxXJGPH0NKphRGGMyKHnYJ+DHi62CXdiRNUIpGHoKI2Z4X2LRn2+hBhw3ysBGyG4l6UqNJmBw7HULkvdiSU0lTtaY8w7JUFgh1QxZ19dq6r3QtxwY5zabRGLcLgM2rlA69ypRqAX4h3oXv0O020qV4ruf9XmnB7kRk4bYGdzh0sePJBQsW7In5qOQpRBh4xaJuoWBSJScbFY6WP21JEbrgtGT6Q+bwIn0fW9/jWAlvRjFViEZr96+CiKIWYqABwNHHuLh9bb4Fc/qgZcPW8h7Sau44laUnpItY5DFbdiUiMZzjheHpORpRyqYq7WiGyASwjrVYxC84DeBaD7YT4ctTXCUsIbFrkrCb4MryD8BMEKbKHfiFScOmWbWINLWxJHrERUQzWRYu1i Rbm/+0k3 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 05.08.25 14:19, Usama Arif wrote: > > > On 05/08/2025 11:36, 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 expect for madvise. >>> - get hugepages only on MADV_HUGE and MADV_COLLAPSE if the global policy >>>    is madvise/always and only with MADV_COLLAPSE if the global policy is >>>    never. >>> - 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 >>> --- >> >> [...] >> >>> +FIXTURE_VARIANT(prctl_thp_disable_except_madvise) >>> +{ >>> +    enum thp_enabled thp_policy; >>> +}; >>> + >>> +FIXTURE_VARIANT_ADD(prctl_thp_disable_except_madvise, never) >>> +{ >>> +    .thp_policy = THP_NEVER, >>> +}; >>> + >>> +FIXTURE_VARIANT_ADD(prctl_thp_disable_except_madvise, madvise) >>> +{ >>> +    .thp_policy = THP_MADVISE, >>> +}; >>> + >>> +FIXTURE_VARIANT_ADD(prctl_thp_disable_except_madvise, always) >>> +{ >>> +    .thp_policy = THP_ALWAYS, >>> +}; >>> + >>> +FIXTURE_SETUP(prctl_thp_disable_except_madvise) >>> +{ >>> +    if (!thp_available()) >>> +        SKIP(return, "Transparent Hugepages not available\n"); >>> + >>> +    self->pmdsize = read_pmd_pagesize(); >>> +    if (!self->pmdsize) >>> +        SKIP(return, "Unable to read PMD size\n"); >> >> Should we test here if the kernel knows PR_THP_DISABLE_EXCEPT_ADVISED, and if not, skip? >> >> Might be as simple as trying issuing two prctl, and making sure the first disabling attempt doesn't fail. If so, SKIP. >> >> Nothing else jumped at me. Can you include a test run result in the patch description? >> > > Instead of 2 prctls, I think doing just the below should be enough: > > diff --git a/tools/testing/selftests/mm/prctl_thp_disable.c b/tools/testing/selftests/mm/prctl_thp_disable.c > index 93cedaa59854..da28bc4441ed 100644 > --- a/tools/testing/selftests/mm/prctl_thp_disable.c > +++ b/tools/testing/selftests/mm/prctl_thp_disable.c > @@ -236,6 +236,9 @@ FIXTURE_SETUP(prctl_thp_disable_except_madvise) > if (!self->pmdsize) > SKIP(return, "Unable to read PMD size\n"); > > + if (prctl(PR_SET_THP_DISABLE, 1, PR_THP_DISABLE_EXCEPT_ADVISED, NULL, NULL)) > + SKIP(return, "Unable to set PR_THP_DISABLE_EXCEPT_ADVISED\n"); > + > thp_save_settings(); > thp_read_settings(&self->settings); > self->settings.thp_enabled = variant->thp_policy; Then probably best to remove the ASSERT_EQ(prctl(PR_SET_THP_DISABLE, 1, PR_THP_DISABLE_EXCEPT_ADVISED, NULL, NULL), 0); From both test functions? You can consider doing the same in patch #5. -- Cheers, David / dhildenb