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Tue, 19 May 2026 06:10:51 -0700 (PDT) X-Received: by 2002:a05:6122:4309:b0:575:fea0:559 with SMTP id 71dfb90a1353d-5760be4191amr9573244e0c.4.1779196251153; Tue, 19 May 2026 06:10:51 -0700 (PDT) Received: from [192.168.2.110] ([70.53.202.134]) by smtp.gmail.com with ESMTPSA id af79cd13be357-9114edfd3ebsm1697995085a.23.2026.05.19.06.10.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 May 2026 06:10:50 -0700 (PDT) Message-ID: <704ae752-eab4-41ba-b0f5-870f7e9e8f06@redhat.com> Date: Tue, 19 May 2026 09:10:39 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/9] mm: introduce pgtable_has_pmd_leaves() To: Lance Yang , david@kernel.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, baolin.wang@linux.alibaba.com, ziy@nvidia.com, corbet@lwn.net, tsbogend@alpha.franken.de, maddy@linux.ibm.com, mpe@ellerman.id.au, agordeev@linux.ibm.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, x86@kernel.org, dave.hansen@linux.intel.com, djbw@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, akpm@linux-foundation.org, lorenzo.stoakes@oracle.com References: <8d365dfa-98e0-478b-ba6b-377c939865d4@redhat.com> <20260517120328.63143-1-lance.yang@linux.dev> From: Luiz Capitulino In-Reply-To: <20260517120328.63143-1-lance.yang@linux.dev> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: TZv4D_6xrPrkk30lX5d8bQSCp07bYisn2ryW-ad7ih8_1779196252 X-Mimecast-Originator: redhat.com Content-Language: en-US, en-CA Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: cnrp6519xt8jcskenuyzs3z7954fp33o X-Rspamd-Queue-Id: 32CB6180014 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1779196254-960849 X-HE-Meta: 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 NJa5j8KY 58AdendrRCTsAa/el1HSfN0AkhIYeUoHY3eqskc2GbFlN1lhrDczQwl1V/pzhlxCN+KS49XOt8GU9GBrH30GOo/iMnNQBukuGg3S3GpTu5y5M7bPcF1CthmAIvZJmQv3lhr0EvqvWad90sdOJ1fGCeDoWuJ7hj1A0in8c7Wo5ujUFrsWwI+Tp8Xgx7xMldIG05gguHyaCN32nGQNlUcSTlzqZ+f/WllopL9BXGiBUwtwt+r12zAMCiKbMVW5Zeo1oAljjlpqC6KuCFR2hM0pWOguRN7f0LQqICJGGqSAOzljcawWW2nod+kHxcd+NM/n0IRU8k9nCwFmqDSvdNb2QTGshj917aggd5eCIK2yDp4oSGCFbs7V+EpydpdVIJGksLIbn9X6FRkWQENl9zPjB648eGlkNrQSahvm74+Jo8BM0jQyWQrxvVWc6+Yy2BBm7IdNeq+zjl2WBt6NGuTslnVTFvWra8lzzSO81 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026-05-17 08:03, Lance Yang wrote: > > On Wed, May 13, 2026 at 09:52:05PM -0400, Luiz Capitulino wrote: > [...] >>>> >>>> #if !defined(MAX_POSSIBLE_PHYSMEM_BITS) && !defined(CONFIG_64BIT) >>>> diff --git a/init/main.c b/init/main.c >>>> index 96f93bb06c49..eea7c5bdddf7 100644 >>>> --- a/init/main.c >>>> +++ b/init/main.c >>>> @@ -1053,6 +1053,7 @@ void start_kernel(void) >>>> print_kernel_cmdline(saved_command_line); >>>> /* parameters may set static keys */ >>>> parse_early_param(); >>>> + init_arch_has_pmd_leaves(); >>> >>> Can't we do this a bit later from some mm code? >>> >>> This feels like something that can just go somewhere into mm_core_init()? > > Indeed. If nobody needs pgtable_has_pmd_leaves() that early, it is > cleaner to put it in MM init code :) > >> Yes, this can be done. My intent in calling it as early as possible was >> to allow callers to use the API from __setup() handlers if needed, but >> since we don't have this case in the code today we can put it in >> mm_core_init() for now. >> >>> There, we should probably call this something like XXX_init(), and prepare it >>> from detecting support for PUD leaves as well. >>> >>> Maybe just >>> >>> pgtable_init() ? >> >> What about pgtable_api_init()? I'm afraid that pgtable_init() might be >> confused with code doing real page table initialization. > > Or what about pgtable_leaf_support_init()? It says what this init is for, > setting up the cached leaf-support check. Today that only means PMD > leaves, but the name still works if we add PUD leaves later :) Yes, I can use that one.