From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (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 932C61EB9E3 for ; Fri, 19 Jun 2026 01:01:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781830911; cv=none; b=Z65rH2ZrUCiOWRuRRPXOEwHRKW0Td5KxNDARnFZ2Rjk3/jmBN1YFTacaVDuN/vxD7zDJr+bARRLfZswk6R8efGTGoMjG45GlLbvnn1YjvQOAxMXQc+iRtNP7NXHTymQJrEclFy1VuOkgXBexUI8B16gZitHKl35+9uTa+syig9Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781830911; c=relaxed/simple; bh=pD7qVnwSjsW0OWNL+3rqpuaix96QO3fg5imVEgbAonc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UQe2JmcvvuA4FVaPWTOEBTR+A3wAEhhj+TLvoE8OK90VsBKl4emcnJibBGN1MuSL+7+Oixo2a7CLgT5rypsXtx+Pxp/QW88Yk4a2B6itZevANa7UI4BMn3fUTPpb4efM//jL8gDAy3FENuVLWB5KWfkliOVzKVq1r4WgCgOJTdo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=fail (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=XlyaE6Xz reason="signature verification failed"; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="XlyaE6Xz" Received: from [10.124.222.133] ([192.55.54.43]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 65J0ixd54112875 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Thu, 18 Jun 2026 17:45:06 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 65J0ixd54112875 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2026052701; t=1781829908; bh=zebuei/XCfNddBBMH37WBz8qxB70cJgeYGFCIcFgfPE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=XlyaE6XzFFlyeKW/M885dO3zXh55BryDmNSsUl8+mrzGUHbyUTLRS8ZtXveKBF0un sepTgT9q/f6ZTRHHTHUspo8hQ3lI6ZnlxE8R2nd5tdu043eLqS+UDl1HlZSh6Tv/34 9Y17SMbzulbhZDbqsyUf5v2gb/JBkFUpd2u9IojONm6/0WMJNYn43FkUXgmSUjd3Ss 9zk1JkvNXOJF0tuBPhaFG6SIS5UkezOnCt21ych72Sp8HcRkg7QbF7vqgxbYJPvWPb bUuEx08slk/WdeLevzHZXrdsi6uqckz6W5t5sW6F+MEr3wdmbtDIK6VrJxoPNrH+/D JrrxSz7gBLpAw== Message-ID: <91d8ba13-977a-41f1-92e0-791f7ffe0c02@zytor.com> Date: Thu, 18 Jun 2026 17:44:54 -0700 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 v2 00/13] Dynamic Kernel Stacks To: David Stevens Cc: Dave Hansen , "Zach O'Keefe" , Pasha Tatashin , Linus Walleij , Will Deacon , Quentin Perret , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Andy Lutomirski , Xin Li , Peter Zijlstra , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Uladzislau Rezki , Kees Cook , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20260424191456.2679717-1-stevensd@google.com> <6369e5ce-74e3-4c68-8053-d7d7d21b6955@zytor.com> Content-Language: en-US, sv-SE From: "H. Peter Anvin" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2026-06-18 17:40, David Stevens wrote: >> >> That is most definitely the zeroth-order thing. Extraordinary claims require >> extraordinary evidence, and this is certainly an extraordinary claim. > > I do acknowledge that there is currently a lack of evidence - this is > an RFC after all. The question is whether it is possible in principle > to produce sufficient evidence. From the Android side of Google, we > are willing to carry the RFC patches downstream for a while to build a > case for merging them upstream. However, there needs to be at least a > possibility of success before we undertake that work. If upstream's > position is that dynamic stacks are no good, full stop, and will > absolutely never happen, then there's no point in us trying to pursue > this avenue further. And I assume those from the datacenter side of > the company are in a similar position. > The answer is pretty much that you would have to present *very* impressive-looking evidence. There is very little that's completely absolute, but you definitely have a tall hill to climb on this one. Keep also in mind that there are also people who claim that our current page sizes are much too small, and that the kernel should be doing 16K or 64K pages. At that point this more or less evaporates, too. -hpa