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[2003:d8:2f25:1e00:ce4c:be3:97b3:6587]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45b9c234b24sm93227735e9.16.2025.09.04.03.23.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 04 Sep 2025 03:23:32 -0700 (PDT) Message-ID: <84297d37-b766-4cfe-9c3f-bff1cb3cb4a4@redhat.com> Date: Thu, 4 Sep 2025 12:23:31 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: tag kernel stack pages To: "Vishal Moola (Oracle)" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton References: <20250820202029.1909925-1-vishal.moola@gmail.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: feKaSEuaP0ebdk3GhGbfkBaD3Ij80R9XfBwqw0FJs6g_1756981414 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 91421160013 X-Stat-Signature: efnopknt6wpfxyqk1m8ipwywycstjbyc X-HE-Tag: 1756981418-237731 X-HE-Meta: U2FsdGVkX19o13fYdsx7Ecrv7ouqw8y26Q7gt/IYkOoyekEyeI7oGP6I5LRWGw0iurRIEFPZWrrHN/AMb9MhOJAKn90RhTrsYXCMshe5E5DyV5ou3Are2xoRfNcRJA9QLmbZrSjtBp0MYtUZLAZmjVORfMEVzZoTaFGM3F/C48gNqv9OQ35Z5hf0Q8l/TAmEzS2r+siEccphutWFZqPPe7G15ETToTTjzLj61C1xHmPUQAlHCxNVVEVynlfm65QXMU94RbH5twwFwx+IrHZo8jbdkO9qObDdFL889NUvB8Vfz5OIINTUeSmnqESleKXIL91d/8u6fgbDLwnAJzOxrKx2y3tR0RGPbfh/TwcqzgizCOuCj8uM8rmuDYVQ+qLZbg1oM9W7iC1IXf6/3jvwS9VmklxKwkVySauQ2cZFNxKbN9OhEVoZXLcL3xqjS+PuVwe48GV3u8ap6Vw57NBfPu1/GKvQNv3eKUbS8K9+EY5uWwuifFuUf69Apm2+ODk3J8tnYKNNjqpY6lH/9IHMVNoTdTEKyk4hsXlQOIP7+bx4ft/nEV8mPcdn8y5e+Iknq6nzlI/FdcV2Y6cO1ZA/sC2/RbZ5AHzxje3cen6xyvspZ1omnwZ4ckaA9xshkaRW/+loLA/jBa/pNKoDt4qngxebuv9JPaQEMycrgr4aRE6UJG7qGTjauxPOdUJkIYx0Q2Ogmeq8UkWhADHQGoBy3ZQcBTM1oe+jxFOPETEkKTOhj115zn1S0cxGMWr7vywfQe7a+llh7MtJZX/HFTKnRYnOdPWuv3s1h2bT+pu1TGVKQDZXqQpayZ4XBf7V6weEw3kFQQbDSRkRZocZ3GxDn5kECKZBEZlGWqLvVLhMEZLHgwJEnqu+7jzjgDSpBX+j5K4vwPxvaPoF91imdrI1jO79CAUKC8gN7WSNmqWaszuwUHC+PMgxKr2B6OvyXzPliyfdMYL6ebYSeBUoBNN BPxUGQ0p 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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 03.09.25 20:19, Vishal Moola (Oracle) wrote: > On Wed, Sep 03, 2025 at 09:49:06AM +0200, David Hildenbrand wrote: >> [resending my original mail because it might have landed in the spam folder] > > Ah, indeed the original mail was found in my spam folder. Thanks for > resending. > >> On 20.08.25 22:20, Vishal Moola (Oracle) wrote: >>> Currently, we have no way to distinguish a kernel stack page from an >>> unidentified page. Being able to track this information can be >>> beneficial for optimizing kernel memory usage (i.e. analyzing >>> fragmentation, location etc.). Knowing a page is being used for a kernel >>> stack gives us more insight about pages that are certainly immovable and >>> important to kernel functionality. >> >> It's a very niche use case. Anything that's not clearly a folio or a >> special movable_ops page is certainly immovable. So we can identify >> pretty reliable what's movable and what's not. >> >> Happy to learn how you would want to use that knowledge to reduce >> fragmentation. 🙂 >> >> So this reads a bit hand-wavy. > > My thoughts align with Matthew's response. If we decide "This doesn't add > enough value to merge it upstream" thats fine by me. > > Otherwise if we think this is useful, I can respin this with your > suggestion below. As raised in my other mail, I assume there is no way to just have any stack pages in any kernel config marked appropriately (slab allocation discussion)? If so, I prefer to not add it. If there is a way to just make it consistent, then no strong opinion from my side. Willy is the page-type guard :) BTW, I was wondering if page-owner could be useful instead. -- Cheers David / dhildenb