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Fri, 14 Apr 2023 17:06:07 -0700 (PDT) Date: Fri, 14 Apr 2023 17:06:06 -0700 In-Reply-To: Mime-Version: 1.0 References: Message-ID: Subject: Re: [PATCH v7 00/14] KVM: mm: fd-based approach for supporting KVM guest private memory From: Sean Christopherson To: Ackerley Tng Cc: brauner@kernel.org, kirill.shutemov@linux.intel.com, chao.p.peng@linux.intel.com, hughd@google.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, linux-kselftest@vger.kernel.org, pbonzini@redhat.com, corbet@lwn.net, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, jlayton@kernel.org, bfields@fieldses.org, akpm@linux-foundation.org, shuah@kernel.org, rppt@kernel.org, steven.price@arm.com, mail@maciej.szmigiero.name, vbabka@suse.cz, vannapurve@google.com, yu.c.zhang@linux.intel.com, luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, qperret@google.com, michael.roth@amd.com, mhocko@suse.com, songmuchun@bytedance.com, pankaj.gupta@amd.com, linux-arch@vger.kernel.org, arnd@arndb.de, linmiaohe@huawei.com, naoya.horiguchi@nec.com, tabba@google.com, wei.w.wang@intel.com Content-Type: text/plain; charset="us-ascii" X-Rspamd-Queue-Id: CAD44C000D X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: ssr7i4okrgr13iehi79nyz88d4hy4wq3 X-HE-Tag: 1681517168-465761 X-HE-Meta: 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 zYtt08tj 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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: On Fri, Apr 14, 2023, Sean Christopherson wrote: > On Fri, Apr 14, 2023, Ackerley Tng wrote: > > Sean Christopherson writes: > > > if (WARN_ON_ONCE(file->private_data)) { > > > err = -EEXIST; > > > goto err_fd; > > > } > > > > Did you intend this as a check that the backing filesystem isn't using > > the private_data field in the mapping? > > > > I think you meant file->f_mapping->private_data. > > Ya, sounds right. I should have added disclaimers that (a) I wrote this quite > quickly and (b) it's compile tested only at this point. FWIW, here's a very lightly tested version that doesn't explode on a basic selftest. https://github.com/sean-jc/linux/tree/x86/upm_base_support