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envelope-from=chenyi.qiang@intel.com; helo=mga03.intel.com X-Spam_score_int: -54 X-Spam_score: -5.5 X-Spam_bar: ----- X-Spam_report: (-5.5 / 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, NICE_REPLY_A=-1.148, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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 12/16/2022 6:30 PM, David Hildenbrand wrote: > On 16.12.22 09:52, David Hildenbrand wrote: >> On 16.12.22 07:22, Chenyi Qiang wrote: >>> vmem->bitmap indexes the memory region of the virtio-mem backend at a >>> granularity of block_size. To calculate the index of target section >>> offset, >>> the block_size should be divided instead of the bitmap_size. >> >> I'm curious, what's the user-visible effect and how did you identify >> this issue? >> >> IIUC, we could end up our search for a plugged/unplugged block "too >> late", such that we miss to process blocks. >> >> That would be the case if the bitmap_size < block_size, which should >> effectively always happen ... >> >> >> unplug_all and migration would be affected, which is why a simple test >> case without a guest reboot/migration wouldn't run into it. > > I just realized that unplug_all is fine because only vfio implements the > ram_discard_listener so far and always sets > double_discard_supported=true. So migration should be the issue (and > IIRC migration with VFIO is still shaky). Yes, actually, no obvious visible effect on my side. I was just learning the RamDiscardManager interface and found this issue. :) >