From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 30F69175A88; Tue, 18 Aug 2026 14:15:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787062539; cv=none; b=IQ/HOR2uMTMgoJwDVbd3VVPIsbKNgVNT4w+ac+7v7Ouz+9/vgGTPOI4XAM7+CApSvZARBn2EMjYNFjQTgcKbHuur+zFdNftRjT3Zc8PQU91bmClR5HaueFTAKzIladXQ5SMCNN6gXsd2LlY6/cXF2eEMPN5+haeKbwG/ukZdgxs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787062539; c=relaxed/simple; bh=3sc9jhutDQogoK0YLOwRMtxdYw3oTIlvs7NVL1reC+U=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=PcvkZkwaVnP8JqVupmB2KWCo+9o7UTzjjivE9JAg8Wc3rNkE0u6W2yGpL1uUwG59qPBt6SyOGDwz7wUplzhkU2pBS5+m7iVlZJ0al7hZ8XPz9jps2HvxZ+uYp4J+yQU1tbxso6/AdWciXmdLsVyk47LKDl0Y6MgaPsK25UL1PHY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=J4txqm8P; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="J4txqm8P" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 528441F000E9; Tue, 18 Aug 2026 14:15:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787062537; bh=Qx7Q9Tkm+30Vy5GpQNpuwA2/ZGcx6zXr2iqGQrjyaow=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=J4txqm8PSDHPtAGQRTxTA5BirFk7+ogzhOIXx818dDoEykvFj2mrVFD5zdFYcfFJ0 /jprkZRDFxQc8+QCcmNb0ApwCPKRCXrDv8FdOKGTuzZSBcmf10N4ZNE2LUmmbewdbR j4nU0aKvIRwA6/P+7rKRyvxb+WqvxxEYHHG++dyYmXrcmPJ4wvxfPuZA75WpgPVgxs f0B9a3AoNrZyoj+6NB3OnEml7VuMxDNvR+DUcxVjWZC/C0Sw9hEPBcvxjPfQATlp3A n0QvsdIbuzJrd8r8lo//noi6umHRcuvqsDdZ55Q9yQZXT5rNReYRnMfBHGHAV80cYT U4t5de0eRoHxA== Message-ID: <99138bda-55ba-4c58-9b79-b76e9daecdde@kernel.org> Date: Tue, 18 Aug 2026 16:15:27 +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: [RFC PATCH 00/57] mm/collapse: rebuild collapse on migration primitives To: Kiryl Shutsemau , "Lorenzo Stoakes (ARM)" Cc: akpm@linux-foundation.org, nico.pache@linux.dev, baolin.wang@linux.alibaba.com, baohua@kernel.org, dev.jain@arm.com, hughd@google.com, lance.yang@linux.dev, liam@infradead.org, mhocko@suse.com, rppt@kernel.org, ryan.roberts@arm.com, shuah@kernel.org, surenb@google.com, usama.arif@linux.dev, vbabka@kernel.org, ziy@nvidia.com, usama.anjum@arm.com, agordeev@linux.ibm.com, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, jannh@google.com, willy@infradead.org, pfalcato@suse.de, rostedt@goodmis.org, mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org References: <20260816224609.308019-1-kirill@shutemov.name> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/17/26 15:38, Kiryl Shutsemau wrote: > On Mon, Aug 17, 2026 at 09:52:13AM +0100, Lorenzo Stoakes (ARM) wrote: >> We have a THP cabal meeting every couple of weeks where it would have been >> useful for you to raise this first. > > Fair -- though my invite is on my old @linux.intel.com address. Could > you forward it to kas@kernel.org? > >> In any case - this series is not something we'd consider at the moment, >> even broken into parts. >> >> David and I have put THP into feature freeze - until the codebase is >> subtantially improved we're not really interested in seeing significant >> development. >> >> The technical debt is substantial and has to be paid down first. >> >> See [0] for a rough list of TODOs in this regard. > > I read the TODO list and I'll pick from it -- though I notice the > technical debt section includes "Literally all of the code in > mm/huge_memory.c and mm/khugepaged.c", which I'd argue this series is a > fairly committed attempt at :) > > One clean up I wanted to do is consolidate code by functionality, not by > the THP/non-THP split. Move all page fault handler code into mm/fault.c, > unmap code into mm/zap.c, fork's copying into mm/fork.c -- mirroring > kernel/fork.c, so the mm half of a subsystem sits under the same name. > Large folios are an integral part of mm nowadays and I don't think we > benefit from keeping THP in a separate file. It is also an opportunity to > shift away from mm/memory.c being a kitchen sink. > > David and I talked about this at LSF/MM. Ah, I missed the context in my other reply. Lorenzo already had some patches at some point to split up mm/memory.c into better chunks that will also better help our subcomponent maintenance model. I think the challenge is how to handle huge_memory.c, because ideally, we'd not have these stupid callbacks into huge_memory.c once we make PMDs just a first-class citizen. This is, unfortunately, also something that needs more thought, because we don't want to end up moving stuff back and forth. -- Cheers, David