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[99.254.144.39]) by smtp.gmail.com with ESMTPSA id z5-20020ae9c105000000b0076077538b0esm3500746qki.17.2023.06.22.07.54.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Jun 2023 07:54:35 -0700 (PDT) Date: Thu, 22 Jun 2023 10:54:34 -0400 From: Peter Xu To: David Hildenbrand Cc: qemu-devel@nongnu.org, "Michael S. Tsirkin" , Juan Quintela , Leonardo Bras , Paolo Bonzini , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Peng Tao Subject: Re: [PATCH v1 1/4] softmmu/physmem: Warn with ram_block_discard_range() on MAP_PRIVATE file mapping Message-ID: References: <20230620130354.322180-1-david@redhat.com> <20230620130354.322180-2-david@redhat.com> <9f7afce0-ff7f-33f8-4f39-bba77f2b2ba4@redhat.com> <0c2d7680-4aa4-9d88-7cc7-62dc3b9535a1@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <0c2d7680-4aa4-9d88-7cc7-62dc3b9535a1@redhat.com> Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Jun 22, 2023 at 03:10:47PM +0200, David Hildenbrand wrote: > Maybe ... depends also on the uffd semantics as in 3). UFFDIO_COPY|ZEROPAGE bypasses page cache for private file mappings, afaict. We'll still got a limit on the inode size (so we can't COPY|ZEROPAGE over that offset of vma) but the rest should be all fine. Feel free to have a quick skim over 5b51072e97d5 ("userfaultfd: shmem: allocate anonymous memory for MAP_PRIVATE shmem"). Thanks, -- Peter Xu