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Sat, 16 Aug 2025 07:07:55 -0700 (PDT) Date: Sat, 16 Aug 2025 14:07:54 +0000 From: Wei Yang To: Aboorva Devarajan Cc: akpm@linux-foundation.org, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, shuah@kernel.org, pfalcato@suse.de, david@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, richard.weiyang@gmail.com, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, donettom@linux.ibm.com, ritesh.list@gmail.com Subject: Re: [PATCH v4 3/7] selftest/mm: Fix ksm_funtional_test failures Message-ID: <20250816140754.tgkn5kwf2i2oe7va@master> Reply-To: Wei Yang References: <20250816040113.760010-1-aboorvad@linux.ibm.com> <20250816040113.760010-4-aboorvad@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250816040113.760010-4-aboorvad@linux.ibm.com> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 3A8BD1C0002 X-Stat-Signature: 3d6yhk9tzp4c66edrio9s9abzddikxcb X-Rspam-User: X-HE-Tag: 1755353276-371410 X-HE-Meta: U2FsdGVkX19mcM25952/696/TWRdE0Bdb2ykQel6L9D7DWAruvA5QumH+2zWh2Y34HrbDJVu0t6YUHkSRaBb4Z7kN4/3Yrny3uypHNR87ywMYJbDHRvKuTUPiVjaBykWxLpvZBnc0p7+PHwzfJYP3OrjRWJrk1MGo6hUHZzPoZZgvn2X84JnBNaumyiQBbutmsaJGOUpUPkQATI2OzRt6Wboa07qfy1ZSRp7Ph/K7/pgUgsXhX+/RCoWOzUpRdiDJwQzS74O+jQpk6B7NKv5X9RT1wLcmOr87oXSNUCmmufgiLvb7kgdKYPpPzoHuFwZafn2WteVhn2G4BXRF6R9JySMC51P4PZyykNpt0VYOTMrOrDJJ28x3KAlcCQM4G6Gh5pC4bSnnTKJA/uKJ7I56RH3LPUw6sTgkuSwVeIw5Zxwd4gf0hgAA6E/LPml/u7tUi6zveyj+jgmWI2WlrKD6YSSYC9X/Lg4uBNIOzVZelAPeHwkY2U3yhLWdQd4ZGyHUuDIZ7TzljtTMoz+v9zzm308aq12Dpogd4kIvUUWpr/uE9OXka+nvDwpWIqLcI4f0y3yQGpJbjGT99oLa8GojotfjU9FqL944Kn8H3sfnNLsYlRAYq1184bsHb6IotC5jTa1dTxfm/gs1pxfTmadRkOeTGITulAZTrgQVUgGmZPkYv6G+YSWXmV43tn8ljbsQYk/+AOkD/y1ANbmj8e8lpytcn65IEBPMav5h4X3WfH9WsiLZHzf5mOCOX2uzn2KWhISHk54r7SJlEuaP9AkvGiqcm5KUovJlm/p4mTimaqb291uQtPkP+AWo6BAfma5y3ybyV3hx/mFgl+D2yMRSq43zApQ4Bg92htdA0724HNjb/Gh64FtN9w/Z5LtPyeN2rZJT9Eom12f9HqBE5dsA85S9zMLzaKNy/N6a4obTb//59gVU0QYCqCfvdFLscGu9lI2KDxVs4BrVdl15Zu 9GY6X4JD 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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 Sat, Aug 16, 2025 at 09:31:09AM +0530, Aboorva Devarajan wrote: >From: Donet Tom > >This patch fixed 2 issues. > >1) After fork() in test_prctl_fork, the child process uses the file >descriptors from the parent process to read ksm_stat and >ksm_merging_pages. This results in incorrect values being read (parent >process ksm_stat and ksm_merging_pages will be read in child), causing >the test to fail. > >This patch calls init_global_file_handles() in the child process to >ensure that the current process's file descriptors are used to read >ksm_stat and ksm_merging_pages. > >2) All tests currently call ksm_merge to trigger page merging. >To ensure the system remains in a consistent state for subsequent >tests, it is better to call ksm_unmerge during the test cleanup phase > >In the test_prctl_fork test, after a fork(), reading ksm_merging_pages >in the child process returns a non-zero value because a previous test >performed a merge, and the child's memory state is inherited from the >parent. > >Although the child process calls ksm_unmerge, the ksm_merging_pages >counter in the parent is reset to zero, while the child's counter >remains unchanged. This discrepancy causes the test to fail. > >To avoid this issue, each test should call ksm_unmerge during cleanup >to ensure the counter is reset and the system is in a clean state for >subsequent tests. > >execv argument is an array of pointers to null-terminated strings. >In this patch we also added NULL in the execv argument. > >Fixes: 6c47de3be3a0 ("selftest/mm: ksm_functional_tests: extend test case for ksm fork/exec") >Co-developed-by: Aboorva Devarajan >Signed-off-by: Aboorva Devarajan >Signed-off-by: Donet Tom Reviewed-by: Wei Yang -- Wei Yang Help you, Help me