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AJvYcCWVzW7Fi93OVmJv/BYGqAsepCiLQXJq8Y+tbsGo6xcQbTKVgW0Yjdg8D6EaflOjHtdfJnuccNbo+g==@kvack.org X-Gm-Message-State: AOJu0YxVzpf7Fmc46WNAs4gn5HwL71+Or1lzBM9pLuKvr91M0etNjurS cTcXPqCBArZOFOA87yYg+5AqQw4LaRPmrIBD9SAijq/3qRzUe8x+hldNwev0YGlrNVke9M0wP1I PTYna6GP08lph539Dt4edJR8SKA== X-Google-Smtp-Source: AGHT+IFTIyctnARP6DvIQOo3ksRMBxmoodQwklk+iQs5yZAGv2sb7oP8liEWVf/ikHodKNA/Kg6t20noqC7nJOCkXw== X-Received: from pfbcw5.prod.google.com ([2002:a05:6a00:4505:b0:748:f4a1:ae2e]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:3d53:b0:748:3385:a4a with SMTP id d2e1a72fcca58-75724e89802mr5954852b3a.23.1752703988027; Wed, 16 Jul 2025 15:13:08 -0700 (PDT) Date: Wed, 16 Jul 2025 15:13:06 -0700 In-Reply-To: Mime-Version: 1.0 References: Message-ID: Subject: Re: [RFC PATCH v2 33/51] KVM: guest_memfd: Allocate and truncate from custom allocator From: Ackerley Tng To: Binbin Wu 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, 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, seanjc@google.com, 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="UTF-8" X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 579A520002 X-Stat-Signature: px7b17oh1qz6grw7mdthx5ckdyf7m7of X-Rspam-User: X-HE-Tag: 1752703989-520041 X-HE-Meta: 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 H2WmwSY3 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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: Binbin Wu writes: > On 5/15/2025 7:42 AM, Ackerley Tng wrote: > [...] >> >> list_for_each_entry(gmem, gmem_list, entry) >> kvm_gmem_invalidate_end(gmem, start, end); >> @@ -776,6 +879,16 @@ static long kvm_gmem_allocate(struct inode *inode, loff_t offset, loff_t len) >> >> start = offset >> PAGE_SHIFT; >> end = (offset + len) >> PAGE_SHIFT; >> + if (kvm_gmem_has_custom_allocator(inode)) { >> + size_t nr_pages; >> + void *p; >> + >> + p = kvm_gmem_allocator_private(inode); >> + nr_pages = kvm_gmem_allocator_ops(inode)->nr_pages_in_folio(p); >> + >> + start = round_down(start, nr_pages); >> + end = round_down(end, nr_pages); > It's weird here. > Should the end be round_up()? > Thanks, you're right. I believe the current consensus is that fallocate() will only be permitted for offset and lengths that are aligned not only to PAGE_SIZE but to allocator page size. In a future revision I'll check for allocator page size earlier on, before this function will get called, so this rounding will probably go away. >> + } >> >> r = 0; >> for (index = start; index < end; ) { >> > [...]