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AJvYcCUPo8+C67Y1NDZgAD9gtIV5BKo58Rmy86DWWg33NxYlDsDabxJIQUJYccDZ3Y+AAgxgTswf70+PnA==@kvack.org X-Gm-Message-State: AOJu0YxNpMGzk7XVu8vT0zw0Yr3A5cvY4GFbW5PP6M5zII73ySG3kYo2 vsuWdRx6G3MsHVUFd+UeZz0TYA1iDvtFfBbzuSxZFa21Bo7wtbMT+9F0LyZ1h4nJjgE3D78dLNX 2Gw4HSg== X-Google-Smtp-Source: AGHT+IGqNOuAruJgEcEZ8T6X7B8VeXMzqceZ1ggBpiDOEhdpqVLI6EnOOFhpmeY8C5TVlMwWJfNoQPt99zY= X-Received: from plbjw19.prod.google.com ([2002:a17:903:2793:b0:273:c5f4:a8ca]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:e786:b0:268:15f:8358 with SMTP id d9443c01a7336-28e9a656d8fmr47206475ad.42.1759507862519; Fri, 03 Oct 2025 09:11:02 -0700 (PDT) Date: Fri, 3 Oct 2025 09:11:01 -0700 In-Reply-To: <2ae41e0d80339da2b57011622ac2288fed65cd01.1747264138.git.ackerleytng@google.com> Mime-Version: 1.0 References: <2ae41e0d80339da2b57011622ac2288fed65cd01.1747264138.git.ackerleytng@google.com> Message-ID: Subject: Re: [RFC PATCH v2 35/51] mm: guestmem_hugetlb: Add support for splitting and merging pages From: Sean Christopherson To: Ackerley Tng Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-fsdevel@vger.kernel.org, aik@amd.com, ajones@ventanamicro.com, akpm@linux-foundation.org, amoorthy@google.com, anthony.yznaga@oracle.com, anup@brainfault.org, aou@eecs.berkeley.edu, bfoster@redhat.com, binbin.wu@linux.intel.com, brauner@kernel.org, catalin.marinas@arm.com, chao.p.peng@intel.com, chenhuacai@kernel.org, dave.hansen@intel.com, david@redhat.com, dmatlack@google.com, dwmw@amazon.co.uk, erdemaktas@google.com, fan.du@intel.com, fvdl@google.com, graf@amazon.com, haibo1.xu@intel.com, hch@infradead.org, hughd@google.com, ira.weiny@intel.com, isaku.yamahata@intel.com, jack@suse.cz, james.morse@arm.com, jarkko@kernel.org, jgg@ziepe.ca, jgowans@amazon.com, jhubbard@nvidia.com, jroedel@suse.de, jthoughton@google.com, jun.miao@intel.com, kai.huang@intel.com, keirf@google.com, kent.overstreet@linux.dev, kirill.shutemov@intel.com, liam.merwick@oracle.com, maciej.wieczor-retman@intel.com, mail@maciej.szmigiero.name, maz@kernel.org, mic@digikod.net, michael.roth@amd.com, mpe@ellerman.id.au, muchun.song@linux.dev, nikunj@amd.com, nsaenz@amazon.es, oliver.upton@linux.dev, palmer@dabbelt.com, pankaj.gupta@amd.com, paul.walmsley@sifive.com, pbonzini@redhat.com, pdurrant@amazon.co.uk, peterx@redhat.com, pgonda@google.com, pvorel@suse.cz, qperret@google.com, quic_cvanscha@quicinc.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, quic_svaddagi@quicinc.com, quic_tsoni@quicinc.com, richard.weiyang@gmail.com, rick.p.edgecombe@intel.com, rientjes@google.com, roypat@amazon.co.uk, rppt@kernel.org, shuah@kernel.org, steven.price@arm.com, steven.sistare@oracle.com, suzuki.poulose@arm.com, tabba@google.com, thomas.lendacky@amd.com, usama.arif@bytedance.com, vannapurve@google.com, vbabka@suse.cz, viro@zeniv.linux.org.uk, vkuznets@redhat.com, wei.w.wang@intel.com, will@kernel.org, willy@infradead.org, xiaoyao.li@intel.com, yan.y.zhao@intel.com, yilun.xu@intel.com, yuzenghui@huawei.com, zhiquan1.li@intel.com Content-Type: text/plain; charset="us-ascii" X-Rspamd-Queue-Id: ED81440017 X-Rspamd-Server: rspam05 X-Stat-Signature: jq6nfnnka6cq71dz9rxdrttgsu8cjmbu X-Rspam-User: X-HE-Tag: 1759507863-626304 X-HE-Meta: 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 MHH9mOEP 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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 Wed, May 14, 2025, Ackerley Tng wrote: > const struct guestmem_allocator_operations guestmem_hugetlb_ops = { > .inode_setup = guestmem_hugetlb_setup, > .inode_teardown = guestmem_hugetlb_teardown, > .alloc_folio = guestmem_hugetlb_alloc_folio, > + .split_folio = guestmem_hugetlb_split_folio, > + .merge_folio = guestmem_hugetlb_merge_folio, > + .free_folio = guestmem_hugetlb_free_folio, > .nr_pages_in_folio = guestmem_hugetlb_nr_pages_in_folio, > }; > EXPORT_SYMBOL_GPL(guestmem_hugetlb_ops); Don't bury exports in an "ops" like this. Be very explicit in what is exported. _If_ KVM needs a layer of indirection to support multiple, custom guest_memfd allocators, then KVM can wire up ops as above. Indirectly exporting core mm/ functionality via an ops structure like this is unnecessarily sneaky.