From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A8EDF3128B0; Thu, 23 Apr 2026 14:14:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776953641; cv=none; b=u7Xx9fCG0fn4ZVBfUdfRgpFAeS5jyDT1bGHA0erU4CGDXeN7TC6iEwjiLvficE35sxRItuEAMrQ5F8uzzvymWykrmjpjiGs0k8ZGLxon/RUicFnr+BIbq5weWcMRyEPef+qbvLgTRasrdydH63HAHt+DALhcntH0ZmhKBQdRnwE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776953641; c=relaxed/simple; bh=EpBTTRg1rLtTK6bSRcJ/pm4319w6ghGNpdcZ0k4OSCg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UC4epb/94JVw/PfQZ8TwAFPyAOP31kjR2ATwLls6s6lI5H1mM2l8QXnS2Kcf9Q+90LTpIR/q3vLum/tZKLVbe4y/EdWHKjUEL3KOSdW9fXMUnBdX8EXK/v5JkEU80hcf9O3pckFd9P6hwZTmw7D+eosbgwyoqx6Mid/f9JCbZSg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hdA87yds; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hdA87yds" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 952A2C2BCAF; Thu, 23 Apr 2026 14:13:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776953641; bh=EpBTTRg1rLtTK6bSRcJ/pm4319w6ghGNpdcZ0k4OSCg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=hdA87ydsV5pc4MAndtcsCuNsC05FxkEo71aDamvg0Sn3MK6iJn6aTihkZinrUFWvK jRXGDUYUDqeUHkVfeHN/wZYfAomPbPiCBWnmiBA49CG5Xv7M3kXXJ4NlSbOzpmVIPY zuA74h3mUbHaz0eEefZgl4F2mYsLsp4d5Krn+/V9776lf0MRQ1/XhFCqNQthKhgJRN v8SXfPzMb9VIvJ2CVpVyUJdt55IEFvNtXdhCtcRZZ503MTinIPvo3ZIHPkwbxWCjv6 fQmIxQ409UeodQVwxzGq2xy8vijJBwS1MYJ7Z3xLGvGuE47iAsndANwd7rzVEqIkSh LStO62t5OdNbA== Message-ID: <88b0765f-7cfc-4e44-83d2-c01a1755c842@kernel.org> Date: Thu, 23 Apr 2026 16:13:50 +0200 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v3 01/19] mm: thread user_addr through page allocator for cache-friendly zeroing To: Gregory Price , "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, Andrew Morton , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , linux-mm@kvack.org, virtualization@lists.linux.dev, Johannes Weiner , Zi Yan , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , "Matthew Wilcox (Oracle)" , Muchun Song , Oscar Salvador , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Ying Huang , Alistair Popple , Hugh Dickins , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , linux-fsdevel@vger.kernel.org References: <9dd9deabd42801f3c344326991d1431c3d8db39d.1776808210.git.mst@redhat.com> <20260422171315-mutt-send-email-mst@kernel.org> <20260423074433-mutt-send-email-mst@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+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 Content-Transfer-Encoding: 7bit On 4/23/26 15:42, Gregory Price wrote: > On Thu, Apr 23, 2026 at 07:57:01AM -0400, Michael S. Tsirkin wrote: >> On Thu, Apr 23, 2026 at 11:46:56AM +0200, David Hildenbrand (Arm) wrote: >> >> Changes we have to add: 8 changes >> Rename 4 existing APIs adding _user: __alloc_pages, >> __folio_alloc, folio_alloc_mpol, __alloc_frozen_pages + add >> 4 wrapper macros/inlines in gfp.h that forward to the _user variants with >> USER_ADDR_NONE. Roughly 6-8 lines of boilerplate per API. >> > > This is essentially what i was proposing. > > The result would be more external surface to the buddy (at least 2 maybe > more functions, plus all the _noprof stuff and a bunch of other things). We probably wouldn't need prof stuff if all we care about is vma_alloc_folio() that will only be calling _noprof internally. > > And then all the callers have to be updated anywhere, and not make it > any harder to mess up. You either have > > old_interface(..., user_addr); > /* Churn everything using the old interface */ > > or > > __internal(..., user_addr) { } > > old_interface(...) { > __internal(..., NO_USER_ADDR); > } > > new_interface(..., user_addr) { > __internal(..., user_addr); > } > > /* > * Update some callsites to use new_interface() > * mostly a bunch of _mpol() functions but some others > */ > > but someone could still just as easily do > > old_interface(); > /* don't fall folio_zero_user() - Bug! */ > > So it's not like this makes things any harder to mess up. Right. Looking at the patch, there would already be less churn if folio_alloc_mpol() __alloc_frozen_pages_noprof() __alloc_pages() post_alloc_hook() Would have simple wrappers. hugetlb calls __alloc_frozen_pages(). That's rather nasty, given that it wants to allocate a frozen folio. alloc_hugetlb_folio() already consumes vma+addr. alloc_buddy_hugetlb_folio_with_mpol() already consumes vma+addr. Maybe we could forward the vma+addr here and call a vma_alloc_froze_folio() if we have a VMA+addr to have a clean interface. But really, that hugetlb code is rather messy. I'd vote for leaving hugetlb alone on a v1, and focusing on non-hugetlb first. -- Cheers, David