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([2620:10d:c092:500::5:7223]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45a23327809sm70936965e9.5.2025.08.18.03.43.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Aug 2025 03:43:39 -0700 (PDT) Message-ID: <5560e517-aa26-4693-baf7-e618bec3c5fa@gmail.com> Date: Mon, 18 Aug 2025 11:43:35 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 6/7] 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 References: <20250815135549.130506-1-usamaarif642@gmail.com> <20250815135549.130506-7-usamaarif642@gmail.com> Content-Language: en-US From: Usama Arif In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: 9dogr31by4jkrrcyfgimbcd3kcpbnzec X-Rspam-User: X-Rspamd-Queue-Id: B563A1C0003 X-Rspamd-Server: rspam01 X-HE-Tag: 1755513821-337902 X-HE-Meta: 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 05QYOA+N 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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 18/08/2025 10:36, David Hildenbrand wrote: >> + >> +TEST_F(prctl_thp_disable_completely, fork) >> +{ >> +    int ret = 0; >> +    pid_t pid; >> + >> +    /* Make sure prctl changes are carried across fork */ >> +    pid = fork(); >> +    ASSERT_GE(pid, 0); >> + >> +    if (!pid) >> +        prctl_thp_disable_completely_test(_metadata, self->pmdsize, variant->thp_policy); >> + > > Skimming over this once more ... this raises two questions > > (a) There is nothing to wait for in the child > (b) Does it work when we return in the child from this function? > > I think (b) works by design of the kselftest_harness, as this function is > itself executed from a child process. > > Regarding (a), it might be cleaner to just > Makes sense, thanks for pointing this out! Have sent the fixlets.