From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 611631CAA9C for ; Thu, 20 Feb 2025 11:22:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740050545; cv=none; b=YvshsgXdSmJL7wfG1+wvVGQAdnlf6udvraLvESWGcrQnCokOC4NNQj+Fcm4Jmy4kY3Kivy99lY3lgo/FFnSnd9NlLqwsv4elLXXAaLOmDPciYPVBVgxkdFz1lTO6zut6lCrMvWpu+dJDpgJeF8elLT4VftpkmoUO0yhJGG9ODX8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740050545; c=relaxed/simple; bh=genpuk4ulAzsvvpb7KWagpKE201ueLa4JpX6K2/5lq4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Jb4mveBmfmeZUecqHZubxbs1M01Os2ComyWMk9ygGdkyiz3Jd/m9/FZDVjGv47sMfoTuB/xGNPrK7vmriadOP1BB88so2fuwAgJCxV9ecEkXfJprzFzeSX+URQT8b+owzc/X8qVu25vYw7B0/mIXV9QqsaTee8bGamqy8SrlvIE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none 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=MylRvPqU; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none 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="MylRvPqU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1740050542; 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=qeOjZ/hnB8RaaYHvFMUcidAycVMGry+64Kvwx9CynFM=; b=MylRvPqUbAftpBom421L6m0dWKm1di4R3tI8o74WurhrOGoEMBigOr+sRrX91FfQnVnCmg ixBYG3lPNNkIiqt+uLPFa9NiZXnXjAiz5oXIypHQDMA7Zic1oYXNcrS0y6NtCECJWCpJRA F1ZfiEzQkg2m1OIexvTwNH/XyX8rUZk= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-617-eol10YlYOB29KJPuSN4DEQ-1; Thu, 20 Feb 2025 06:22:21 -0500 X-MC-Unique: eol10YlYOB29KJPuSN4DEQ-1 X-Mimecast-MFC-AGG-ID: eol10YlYOB29KJPuSN4DEQ_1740050540 Received: by mail-wr1-f72.google.com with SMTP id ffacd0b85a97d-38f39352f1dso290435f8f.0 for ; Thu, 20 Feb 2025 03:22:20 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740050540; x=1740655340; h=content-transfer-encoding:in-reply-to:organization: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=qeOjZ/hnB8RaaYHvFMUcidAycVMGry+64Kvwx9CynFM=; b=i1vF0py5xYC8RSSBYc5Yo9EVqpXVvB0d9jkQf21qRXz9CKIJN2fy8uis9feZwtMjT1 bpocgWz53FQyeNtKKyJDHABzbvvYRX3ZFYix3fxYIQgU1u7Fzp4SB9sS3Mf3mrEz6JDF DaUCWmtA8TbmKcKCytx+qxI94mPfyV35OBHalfVOVimrYqxuYvChfsZeJh13Jgtj1tp1 gSAT8G05LkhwsH25PytONEczHNUti8b0FFKSSGKNoujpcsem6SdnNyxHTQVEKdMB7JNR pcaDkYJOl/lR+w8LOexAQBnEhGcpY6fPjbQriCvHtCS3di/I6K0Fw4jBqLkjm8+t16KF VMZw== X-Gm-Message-State: AOJu0YwQbSmHXx4ZNXnq+PpMuKy2vKSAQBC3OQ/UmdODSwG7qI8LXPpX 0xkcExeqyWaut+hupk1A3y5CDMtO0BUSsYqVRC39l+EfgAQFGw1hMmsTAI1YQ4e/ueumdtRhYjm WbF0vRO0qFxembtjW/D8lD6vb6LudZrGLaKJ1SbBuvDOTc33H3Q== X-Gm-Gg: ASbGncuHuBqRzGQM2VnGxUi+STGDVG/tQEi5Qsc6B/t1EO8FrZi8lrx6YcXUekkoBEU T7K9r66Teo6bRV360rfczfUT8cHCPU8PjvuEq3rri9PQIoiPl22trBOrSA1lnV/Sl1nY8mdMx7P keYkdV5Rqy59RyHoJDSYU6me/u61VD5jjAQ/ejssg2in/cTwdk0QZkrUiuKVg0r1HWL2ddgox6C FL+JGl7I36NCVE90kRuepGeQoA6TMXTxwayRgq3ae46/kyFbo1v4IkC6fJt31ZIAnk3fpC5xdNM iq2hsAcAuU6OxaYduepU0FFQkHa9o+eGNvlPutNNaIpoQbYSoubyYRa8qSyYDKfiPdv2vP9r+Qb 3UA/t7XyHAzeVmtkG6GJ0OPjqcUP2qg== X-Received: by 2002:a05:6000:401f:b0:38f:4531:3989 with SMTP id ffacd0b85a97d-38f45313c69mr15308460f8f.51.1740050539838; Thu, 20 Feb 2025 03:22:19 -0800 (PST) X-Google-Smtp-Source: AGHT+IE2eWtb22S7oNj+/l6FEu7i35FzW/IpI8duJQRdm/4j6MY1SRnCGQx6tqwYA1CyL5PIvebnLQ== X-Received: by 2002:a05:6000:401f:b0:38f:4531:3989 with SMTP id ffacd0b85a97d-38f45313c69mr15308436f8f.51.1740050539369; Thu, 20 Feb 2025 03:22:19 -0800 (PST) Received: from ?IPV6:2003:cb:c706:2000:e44c:bc46:d8d3:be5? (p200300cbc7062000e44cbc46d8d30be5.dip0.t-ipconnect.de. [2003:cb:c706:2000:e44c:bc46:d8d3:be5]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38f259f7998sm20070841f8f.82.2025.02.20.03.22.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 20 Feb 2025 03:22:18 -0800 (PST) Message-ID: <843edd7f-354e-48ee-a45f-671d0497a5cd@redhat.com> Date: Thu, 20 Feb 2025 12:22:14 +0100 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 02/11] KVM: guest_memfd: Handle final folio_put() of guest_memfd pages To: Fuad Tabba , Vlastimil Babka Cc: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, yu.c.zhang@linux.intel.com, isaku.yamahata@intel.com, mic@digikod.net, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com References: <20250211121128.703390-1-tabba@google.com> <20250211121128.703390-3-tabba@google.com> <4311493d-c709-485a-a36d-456e5c57c593@suse.cz> 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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit >>> +#endif >>> + >>> #endif >>> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h >>> index 6dc2494bd002..734afda268ab 100644 >>> --- a/include/linux/page-flags.h >>> +++ b/include/linux/page-flags.h >>> @@ -933,6 +933,17 @@ enum pagetype { >>> PGTY_slab = 0xf5, >>> PGTY_zsmalloc = 0xf6, >>> PGTY_unaccepted = 0xf7, >>> + /* >>> + * guestmem folios are used to back VM memory as managed by guest_memfd. >>> + * Once the last reference is put, instead of freeing these folios back >>> + * to the page allocator, they are returned to guest_memfd. >>> + * >>> + * For now, guestmem will only be set on these folios as long as they >>> + * cannot be mapped to user space ("private state"), with the plan of >> >> Might be a bit misleading as I don't think it's set yet as of this series. >> But I guess we can keep it to avoid another update later. > > You're right, it's not in this series. But as you said, the idea is to > have the least amount of churn in the core mm code. I proposed adding the latter, to make it clearer that the purpose of these things is to be mapped to user space long-term (-> be a proper folio, like hugetlb folios will have to be), compared to long-term not being a folio (slab, offline, unaccepted, ...). Might become relevant for people working on the memdesc work, to know what to do here. (or at least have less questions :) ) -- Cheers, David / dhildenb