From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8B5521917F4 for ; Thu, 4 Sep 2025 10:23:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756981419; cv=none; b=urZhMgyYcJ4xsk7cMxwcHmEM/oiQCyOJL6INWp5OjCX6Xx0rGq/WVOM4iwMlrMsFFLLiDCoDL6X0Kb3wzHUtOnujwrWo1w+s0oCp6W25NAJUE2IEQ1EFcACNDF0IxXrwdX+TW5/jG1b51yg8hv4UvLmBkY4B28hrvmSWeWr3pn8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756981419; c=relaxed/simple; bh=/Nq0rAF47wBI+nCOVbe+IZHqKyzQrkLnb+8Fv7fZw6A=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SOn9NTb0fygBbWcnVTozzE0NxyjkysgORmmGbb7c2W6P0MTZ3gB60Fro6XErghUcavTs/pbevLMYC3t+3CWzMql/xKC79VU+v+ZKCXaDN9MmEnka6UiH5xXljy/INeYjcU2DH7cLFfS/v/wWckP1eo95Acjjxux75OA7SASN4vA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=OU1pfG58; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="OU1pfG58" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1756981416; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=HMLyLUiUh/TZRBZyhVrvLseu1BaUclOXEJcDQ74FaJg=; b=OU1pfG58DDCgTNfMh8ee6UkqbkRLOSyI7StFmFRwVQrErPENCQxfm8GIZxdo56l1/31fU2 JSMzFeAVaGuCaxPcEg3D6jylPlJLd/0/hD3tFATv/Qsegzi0pzyikF3BokqBl8dGf4W621 dwV6SR9XQdM7OWAFrK59S9RZkHGfFYo= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-664-D9oYzwOiOna-4bh-mRUq1Q-1; Thu, 04 Sep 2025 06:23:35 -0400 X-MC-Unique: D9oYzwOiOna-4bh-mRUq1Q-1 X-Mimecast-MFC-AGG-ID: D9oYzwOiOna-4bh-mRUq1Q_1756981414 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-45b71eef08eso5583025e9.0 for ; Thu, 04 Sep 2025 03:23:35 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1756981414; x=1757586214; h=content-transfer-encoding:in-reply-to:autocrypt:content-language :from:references:cc:to:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=HMLyLUiUh/TZRBZyhVrvLseu1BaUclOXEJcDQ74FaJg=; b=BSRtOWjSut3KwUw7oKQYa7sDfg3m620MoJIwAr6U5saFq996nRdTgvAGpFVj3o9tvH Tckh19JrfRUr3L4xnPWrCzAzMdje98kCc4PAK0DmwcVfEAEKTNaGb5Yj+zweuj2R0yoo +4My3Tf0d+oLEcJaK9aI5u5mVtBQ9I9aeJbo6DnykgsJDitNCWUcb+yIPy/3i/txoOdI tMDQl4M4CujcjUb4cNqgro7ZtulOSGgJ/YUAAKSANAq9TGtyBdJxspfGSRB6I2mRmPo0 cLOx/4D83aS/yVtNckGeuQBXkbOcENtbnuGEexmrGXW8b/VDN2B1aJ9/WLNy0c4SB7lr uk0Q== X-Forwarded-Encrypted: i=1; AJvYcCW9hjCaVXn9HK6LJOI/AfVknEUts5EOOb1h76I5+fFQFSU4T+ogwM9EQUvI9g+CsID0EsU2SOwg4TV2BJU=@vger.kernel.org X-Gm-Message-State: AOJu0YxZ65If/j8tTHIerkqWtARzU3pDU3POP2LwABOSS395H5+QNef4 G1P1IhyPLAw2/806WP9z9wFbWRa4ARpkGWnSYwekALuG6OKxKkA/5irkHpcQH08DUlNA62zRfIw TP/IGnt5huKD1wAOPtHf38tyBzIcDUkcE76/ivBSKRyxknbrdYe5zn2Ep/Rw97aOIqA== X-Gm-Gg: ASbGnctC5RPk4RRRPdnRJCnp1ytyo4eeSPnh4pi0sGxCuR1nbbU0HRKzlgZIOb9c6PD ssT4roVXBgyxrgCHsj7ZkyH5LiC3h72Rh0HgWqG3036OUnKMNqOxZ8wBwsV/CfPhHjMuFFP9uwr SdW1MoxfpVycMOglgmBQLNibbfWSJp29pp2wDJro66lJHomEOwdzdyt4ItxOOOW1vGUbP3yz651 PQJ9GJTLpqWz19yQ1AcbKAslv/0IwGowf5Ziidll00dGWewCSpQpQqT4joHvhesWjkeGFz9/Vmt uh4AMPAiT1GpoELe6Z18JIBnc3pa/z4z2xITckQZ+/LJHDfldR9xy3XjTxXHANZclVZcx1+viFj DKJzQXecABslO8NG01Rv4gEOX+0zVaLFKGd5BSPlcyIVA9wyc3tkbDXxEVqtnRa/1 X-Received: by 2002:a05:600c:4fc9:b0:45d:cfc7:a16a with SMTP id 5b1f17b1804b1-45dcfc7a1f2mr20239895e9.9.1756981414035; Thu, 04 Sep 2025 03:23:34 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFyPrZckgqxIwcSXvcmROdXN20zf4ciUTUtqMgHL+vb5j2/auofdb1B1OI/l2DtECrLUTB1bw== X-Received: by 2002:a05:600c:4fc9:b0:45d:cfc7:a16a with SMTP id 5b1f17b1804b1-45dcfc7a1f2mr20239595e9.9.1756981413558; Thu, 04 Sep 2025 03:23:33 -0700 (PDT) Received: from ?IPV6:2003:d8:2f25:1e00:ce4c:be3:97b3:6587? (p200300d82f251e00ce4c0be397b36587.dip0.t-ipconnect.de. [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 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] 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 Content-Language: en-US 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: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 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