We are reading the a BBM (Big Block Mode) value while in SBM (Sub Block Mode) while initializing. Fortunately, vm->bbm.bb_size maps to some counter in the vm->sbm.mb_count array, which is 0 at that point in time. No harm done; still, this was unintended and is not future-proof. Fixes: 4ba50cd3355d ("virtio-mem: Big Block Mode (BBM) memory hotplug") Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx> Cc: Jason Wang <jasowang@xxxxxxxxxx> Cc: Marek Kedzierski <mkedzier@xxxxxxxxxx> Cc: Hui Zhu <teawater@xxxxxxxxx> Cc: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx> Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> --- drivers/virtio/virtio_mem.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c index 9fc9ec4a25f5..6d4e01c4e2fa 100644 --- a/drivers/virtio/virtio_mem.c +++ b/drivers/virtio/virtio_mem.c @@ -2409,6 +2409,10 @@ static int virtio_mem_init(struct virtio_mem *vm) dev_warn(&vm->vdev->dev, "Some memory is not addressable. This can make some memory unusable.\n"); + /* Prepare the offline threshold - make sure we can add two blocks. */ + vm->offline_threshold = max_t(uint64_t, 2 * memory_block_size_bytes(), + VIRTIO_MEM_DEFAULT_OFFLINE_THRESHOLD); + /* * We want subblocks to span at least MAX_ORDER_NR_PAGES and * pageblock_nr_pages pages. This: @@ -2453,14 +2457,11 @@ static int virtio_mem_init(struct virtio_mem *vm) addr = vm->addr + vm->bbm.bb_size - 1; vm->bbm.first_bb_id = virtio_mem_phys_to_bb_id(vm, addr); vm->bbm.next_bb_id = vm->bbm.first_bb_id; - } - /* Prepare the offline threshold - make sure we can add two blocks. */ - vm->offline_threshold = max_t(uint64_t, 2 * memory_block_size_bytes(), - VIRTIO_MEM_DEFAULT_OFFLINE_THRESHOLD); - /* In BBM, we also want at least two big blocks. */ - vm->offline_threshold = max_t(uint64_t, 2 * vm->bbm.bb_size, - vm->offline_threshold); + /* Make sure we can add two big blocks. */ + vm->offline_threshold = max_t(uint64_t, 2 * vm->bbm.bb_size, + vm->offline_threshold); + } dev_info(&vm->vdev->dev, "start address: 0x%llx", vm->addr); dev_info(&vm->vdev->dev, "region size: 0x%llx", vm->region_size); -- 2.29.2 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization