From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D69CC0218A for ; Thu, 30 Jan 2025 17:17:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 942A5440154; Thu, 30 Jan 2025 12:16:59 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 91857440151; Thu, 30 Jan 2025 12:16:59 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7B8E5440154; Thu, 30 Jan 2025 12:16:59 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 5DFF8440151 for ; Thu, 30 Jan 2025 12:16:59 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id A09561403E7 for ; Thu, 30 Jan 2025 17:16:53 +0000 (UTC) X-FDA: 83064773148.12.F793B88 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf11.hostedemail.com (Postfix) with ESMTP id 0292740008 for ; Thu, 30 Jan 2025 17:16:50 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Ag+DNfYf; spf=pass (imf11.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1738257411; h=from:from:sender: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:dkim-signature; bh=7I17JIDXaCz2JzuRPmuH7UMSeK2Y9qHccuoT9T2xKBc=; b=p/tYovxpvTp+31KCihFE1Rmf0CUmPVz+ke+rfnvBooFVwKUzU4vph7K2bnd/odNldBenlo jEPprirwcgnPm8kNrfk3C571L6xDVi5q2zsgIVGQu3zHAMPRtcMErvJtZkd47GLP6DDBok xuwjb5bTPSfQjklFj3QUbJN15DB9sVw= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Ag+DNfYf; spf=pass (imf11.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1738257411; a=rsa-sha256; cv=none; b=bzPj0Ou6QFo6CiiMIZHFo99R9S8/tN+ur+FFXaQd+IXRmjIK18PbRJ+BPo+YKksBN8VtoD rMcuErzVIGgjcOVE0kdfp6UkUCHYUaLhM/tEfRCIQ0EzXVnFNfONvz2iAnNFLRW17/VXC9 WNf4iNYdL19PX8skUWVNEkqO/c2QgjE= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1738257410; 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=7I17JIDXaCz2JzuRPmuH7UMSeK2Y9qHccuoT9T2xKBc=; b=Ag+DNfYfduUXZulW7SkS6/LEN7kqmZjdlbgkqnUZQrEyyrUD7k6iT09KW7LJbkV5TnwCU4 mPoxNFmxg4DEwaZ7SvsYXQMmTCIgKLrFiSPkyoXC/n5utDPvYSwlkKdF82jGB8WK5eP0ti Jz4Dd+WcRtB5syDy/ITq+8a2jPg7N0s= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-34-DXyg-EePMJ-yqegApmrxrg-1; Thu, 30 Jan 2025 12:16:49 -0500 X-MC-Unique: DXyg-EePMJ-yqegApmrxrg-1 X-Mimecast-MFC-AGG-ID: DXyg-EePMJ-yqegApmrxrg Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-3862a49fbdaso426668f8f.1 for ; Thu, 30 Jan 2025 09:16:49 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738257408; x=1738862208; 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=7I17JIDXaCz2JzuRPmuH7UMSeK2Y9qHccuoT9T2xKBc=; b=eqUVJM/nl4F/yvZZyKljfFwa5wkWmA6US+a+XNBFRPUDHt2EsJNrVg+Uh7FnpGmD5m NsbDTUY2LvNfwZ4UIbnQxjE8aBio71d1wJgbJ03/YYl0HAmAByYy8Y/qFvJoWrCmSlt8 x4uIoOzWjzhLR895U06+FY0DfItoESZpujUmQYR/agYjborsxXSx6tyLxx8aE+DKl+Nx iQwO3Foo0tZA/4bYHljLxBLU7TXJCUXkcc+Ty/UPJ5MAVfYjkhU4L6hpTmRW6KpgYJMI PEOLyvG/Y8GGdyXsJS5qUWRcZJdck3a6HTjFd7dQ7kIaV3JvswNH8e5lYfZVOpmiMzzr 2zmw== X-Forwarded-Encrypted: i=1; AJvYcCUhT5bsdofb7+Y/cZkV5BIsBNlISM69K1Np66bKqqXUJpUHY4/zOa+rAQCs6AMCIE7KCdUHd1Pwew==@kvack.org X-Gm-Message-State: AOJu0YwAEaYR5HWS1d7g3wi0rfvsX91AMZ31s2YRpoRiuorciRbX+qX4 rtmus/fX2LJ/IhWheI7xEHnyVwyCerj4FhcwgMhq1jIqif6DoOttxT7XMPOXyQwKh3diRb9CRMq B0GnCPt2GF+enphV/dib+Ua/oEjsMTnxWtqlz8IyR3CoOgtbI X-Gm-Gg: ASbGncvmord3tGrM7jzV5JglOYVC1B73B1ZLchPfwH5BE3MyCknTTugz6YRw0tbIBUA hKwz/w7IWxmsGFxLNINNUWi4+Or1X/Xvm1V1VTufo6GxLOeSI6tE2BcTVRr0qfiUZ9QPeicuQ0E Eqysj1XEDxoghXJ9D1fk4RHwQN7cEZS62iWSvOJnadPqah41ffMWfSTf3aGSCbtJoclwugZNuDa tB8nl2Sj3ThEz7SFHQV7zc5OAi0+F/XcbALm4Lh0MCMaUdDMuqefgnDQw51cD3Q79A4cZ2F2r0I /9AL4uYd30xCKmks8RomIFLMWdZma1QDCyvLcyusCW6k78h3Mc7pHiFy/6JBKDQL3+LhpCj0Q/G AA2448dOA5CZnza3csavDKCe+MgoUVEQj X-Received: by 2002:a5d:44c6:0:b0:38a:615b:9ec0 with SMTP id ffacd0b85a97d-38c520ba752mr5537362f8f.54.1738257407977; Thu, 30 Jan 2025 09:16:47 -0800 (PST) X-Google-Smtp-Source: AGHT+IFYw5/qlXKHyO1lZnIDDimnBb1xIpO0uKlfI98ghzRA32zLq8WeDKR9kGlGsWPK50fTQgP0Rg== X-Received: by 2002:a5d:44c6:0:b0:38a:615b:9ec0 with SMTP id ffacd0b85a97d-38c520ba752mr5537286f8f.54.1738257407543; Thu, 30 Jan 2025 09:16:47 -0800 (PST) Received: from ?IPV6:2003:cb:c713:3b00:16ce:8f1c:dd50:90fb? (p200300cbc7133b0016ce8f1cdd5090fb.dip0.t-ipconnect.de. [2003:cb:c713:3b00:16ce:8f1c:dd50:90fb]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38c5c1cf896sm2623894f8f.94.2025.01.30.09.16.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Jan 2025 09:16:46 -0800 (PST) Message-ID: <0ca9f444-b63f-4259-9462-014e0d0f1a74@redhat.com> Date: Thu, 30 Jan 2025 18:16:42 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v2 02/11] KVM: guest_memfd: Handle final folio_put() of guest_memfd pages To: Fuad Tabba , kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org Cc: 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, vbabka@suse.cz, 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: <20250129172320.950523-1-tabba@google.com> <20250129172320.950523-3-tabba@google.com> From: David Hildenbrand 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: <20250129172320.950523-3-tabba@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: matAOSjoyc9hNcvsWvAQSZ46zWdHVFIHnmvwV7i_AQo_1738257408 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 0292740008 X-Stat-Signature: o47ankcsbs6gtregbcqceeo1i1z9nno3 X-Rspam-User: X-HE-Tag: 1738257410-536404 X-HE-Meta: U2FsdGVkX1/7s+f98Mk/rguMgAUKJxli2wYKLycd5+tp/e6GQ4ps3nT6rbL54yqbEYJFLw2G5hknmrCisTgwC37/jNCmRLYoci26rZTNa4Z1fpSXCmjU/s1BYn1VwaTcVecrrcA4eOHDG/d6UtB7MYroXpfpLpA8knoNRMYiDgUIJBcu+YTw1/6JutIuzSFkFvFXUIQV8zuToNNbyXeA/fGJQfrGvn/TZD9jtWS8g71lJX9IR2a0++mep7tYvr9AVFq2oqTfMpOZ6AmUQrZp2UqTIn6p3kIjK53YjPhhr8hUrBtIhrpduWo0zXJErjQkwhuOSk1DOxEyAXzoKNo+Pr2oIpJrlBaFdY2JR3Q0A/HXymAT3q1wZEwGANPgiDpomzDhtKEJwk+Gq75aJoAzCU9plr720hDljlM0mUgs4L7zqyUpL6Z6qSYnM+pDwRpf0wxAU84hwH+wfStvcupdD/MvrY3AtoTjVjEiuD55gSzF0hBqEKP5yZ3WHP1SNSpKsXCoifWCE2Mw7AE4jEXUNFUvGNJ3IMMBTEsCwCtpXGMa6qqXpbyi4sl4+5cNQ0s5Oq49oCyNgiZ1xa//YtblovksxHinDHXUx/z6zBTt9f9uZQCi0ik4qXCmCfU05BCo7asezDQG1hU/JE3TR2pwY6d5RaWre5hJgxcM+/xRPXsJAtgcskCPAUlTsUwU/ZkrXWuiZxILc/VIJ2Y6ua2B/7crbaMCHEIJd/Ayke3kEZGoykleUoqNvVDEAwOtlnBAJ0RbD+/X0tRINHZk+rbFnxykPL1pqhNmz0o4BP+lWu+iVAX2lDovB9RVLYOZOs4LQkEUU4isQL8nRkEaVPFibvahOl0cXpWqMq5JUjKkg89P9dy++wKIjRTXp1DuitTWe0O4NpE9/Jipg1m7nZr6BEkZa3sHU85XFgItteFNG9CrBgDf3+hoRho4H2votG0JfrasEZrhDgIqo2z8anH pthIJ17a 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 29.01.25 18:23, Fuad Tabba wrote: > Before transitioning a guest_memfd folio to unshared, thereby > disallowing access by the host and allowing the hypervisor to > transition its view of the guest page as private, we need to be > sure that the host doesn't have any references to the folio. > > This patch introduces a new type for guest_memfd folios, which > isn't activated in this series but is here as a placeholder and > to facilitate the code in the next patch. This will be used in > the future to register a callback that informs the guest_memfd > subsystem when the last reference is dropped, therefore knowing > that the host doesn't have any remaining references. > > Signed-off-by: Fuad Tabba > --- > include/linux/page-flags.h | 7 +++++++ > mm/debug.c | 1 + > mm/swap.c | 5 +++++ > 3 files changed, 13 insertions(+) > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index 6615f2f59144..bab3cac1f93b 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -942,6 +942,7 @@ enum pagetype { > PGTY_slab = 0xf5, > PGTY_zsmalloc = 0xf6, > PGTY_unaccepted = 0xf7, > + PGTY_guestmem = 0xf8, > > PGTY_mapcount_underflow = 0xff > }; > @@ -1091,6 +1092,12 @@ FOLIO_TYPE_OPS(hugetlb, hugetlb) > FOLIO_TEST_FLAG_FALSE(hugetlb) > #endif > Some short doc would be nice, to at least hint that this is related to guest_memfd, and that these are otherwise folios. /* * guestmem folios are folios that are used to back VM memory as managed * 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 * always setting that type once typed folios can be mapped to user * space cleanly. */ > +#ifdef CONFIG_KVM_GMEM_MAPPABLE > +FOLIO_TYPE_OPS(guestmem, guestmem) > +#else > +FOLIO_TEST_FLAG_FALSE(guestmem) > +#endif > + > PAGE_TYPE_OPS(Zsmalloc, zsmalloc, zsmalloc) > > /* > diff --git a/mm/debug.c b/mm/debug.c > index 95b6ab809c0e..db93be385ed9 100644 > --- a/mm/debug.c > +++ b/mm/debug.c > @@ -56,6 +56,7 @@ static const char *page_type_names[] = { > DEF_PAGETYPE_NAME(table), > DEF_PAGETYPE_NAME(buddy), > DEF_PAGETYPE_NAME(unaccepted), > + DEF_PAGETYPE_NAME(guestmem), > };> > static const char *page_type_name(unsigned int page_type) > diff --git a/mm/swap.c b/mm/swap.c > index 8a66cd9cb9da..73d61c7f8edd 100644 > --- a/mm/swap.c > +++ b/mm/swap.c > @@ -37,6 +37,7 @@ > #include > #include > #include > +#include > > #include "internal.h" > > @@ -101,6 +102,10 @@ static void free_typed_folio(struct folio *folio) > if (IS_ENABLED(CONFIG_HUGETLBFS)) > free_huge_folio(folio); > return; > + case PGTY_guestmem: > + if (IS_ENABLED(CONFIG_KVM_GMEM_SHARED_MEM)) > + WARN_ONCE(1, "A placeholder that shouldn't trigger."); Does it make sense to directly introduce the callback into guest_memfd and handle the WARN_ONCE() in there? Then, we don't have tot ouch this core code later again. -- Cheers, David / dhildenb