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b=Hgkr4hg7zQXTt/YOkRxPkZIHUtK1zTNcywzH1MTqkkREzmi+9td5X05r118VG/gIv EUhIpque6aM/JP1B3c6Vr0hPdX5qI+jqzi3lt2YguscLplbGdsloC37l/N6PfVU0CG 3BB+Li1V5rF2Lm7aIiOKKHmYDkcoC8MS2OnOO6CE= Date: Thu, 19 Mar 2026 19:43:47 -0700 From: Andrew Morton To: Waiman Long Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Tejun Heo , Michal =?ISO-8859-1?Q?Koutn=FD?= , Shuah Khan , Mike Rapoport , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Sean Christopherson , James Houghton , Sebastian Chlad , Guopeng Zhang , Li Wang Subject: Re: [PATCH 0/7] selftests: memcg: Fix test_memcontrol test failures with large page sizes Message-Id: <20260319194347.1048fc8d737b6e8f9d82663d@linux-foundation.org> In-Reply-To: <20260319173752.1472864-1-longman@redhat.com> References: <20260319173752.1472864-1-longman@redhat.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: je5adg6pgxbstaeez14qph1meapdfkyc X-Rspamd-Queue-Id: 1368B12000D X-Rspamd-Server: rspam03 X-HE-Tag: 1773974629-766196 X-HE-Meta: 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 zkpKhHk5 8Ro+y/sPntbuft0+pSp3MjXlCtOFLFJh3yZc+L4dahgrvDTZrE1y3ovhhnGpNkajisdKhD9kiwWz/n9FylPVR7MMmbaLz8d8THje3eK28ROK5o2u8OzggcXpa8VVHb3QLEs3rEi0AkMZCcIbkYPdYIUiSGu7vXwM0SdkE2+j30F1lluQdiAs0SdA453LBw6HGHyz6m6YO9o3wWkANTzaYe6b6n4kegi7mgng1tb6mjtKCqZVvsaU5QKDcpeYxKducqk8WV9zJ6JZcpc0hRTExvqavNA9hrDg67yWQHsLz8YuUR1U7wTwk3PxmADiz2p/1FydvZNKtGbr/3NtosfKL32AbSJTzHTE9Iocn6MnI5Qc0lJxchYrBM0GmlxA+vCogihMq Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 19 Mar 2026 13:37:45 -0400 Waiman Long wrote: > There are a number of test failures with the running of the > test_memcontrol selftest on a 128-core arm64 system on kernels with > 4k/16k/64k page sizes. This patch series makes some minor changes to > the kernel and the test_memcontrol selftest to address these failures. > > The first kernel patch scales the memcg vmstats flush threshold > logarithmetically instead of linearly with the total number of CPUs. The > second kernel patch scale down MEMCG_CHARGE_BATCH with increases in page > size. These 2 patches help to reduce the discrepancies between the > reported usage data with the real ones. > > The next 5 test_memcontrol selftest patches adjust the testing code to > greatly reduce the chance that it will report failure, though some > occasional failures is still possible. > > To verify the changes, the test_memcontrol selftest was run 100 > times each on a 128-core arm64 system on kernels with 4k/16k/64k > page sizes. No failure was observed other than some failures of the > test_memcg_reclaim test when running on a 16k page size kernel. The > reclaim_until() call failed because of the unexpected over-reclaim of > memory. This will need a further look but it happens with the 16k page > size kernel only and I don't have a production ready kernel config file > to use in buildinig this 16k page size kernel. The new test_memcontrol > selftest and kernel were also run on a 96-core x86 system to make sure > there was no regression. AI reviewbot asks questions: https://sashiko.dev/#/patchset/20260319173752.1472864-1-longman%40redhat.com