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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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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> Content-Language: en-US, en-CA From: Luiz Capitulino In-Reply-To: <20260517120328.63143-1-lance.yang@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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.