@@ -407,6 +407,7 @@ static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id)
{
const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
int nid = vm->nid;
+ int rc;
if (nid == NUMA_NO_NODE)
nid = memory_add_physaddr_to_nid(addr);
@@ -423,8 +424,17 @@ static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id)
}
dev_dbg(&vm->vdev->dev, "adding memory block: %lu\n", mb_id);
- return add_memory_driver_managed(nid, addr, memory_block_size_bytes(),
- vm->resource_name);
+ rc = add_memory_driver_managed(nid, addr, memory_block_size_bytes(),
+ vm->resource_name);
+ if (!rc) {
+ /*
+ * Try to reduce the number of system ram resources in our
+ * resource container. The memory removal path will properly
+ * split them up again.
+ */
+ merge_system_ram_resources(vm->parent_resource);
+ }
+ return rc;
}
/*
virtio-mem adds memory in memory block granularity, to be able to remove it in the same granularity again later, and to grow slowly on demand. This, however, results in quite a lot of resources when adding a lot of memory. Resources are effectively stored in a list-based tree. Having a lot of resources not only wastes memory, it also makes traversing that tree more expensive, and makes /proc/iomem explode in size (e.g., requiring kexec-tools to manually merge resources later when e.g., trying to create a kdump header). Before this patch, we get (/proc/iomem) when hotplugging 2G via virtio-mem on x86-64: [...] 100000000-13fffffff : System RAM 140000000-33fffffff : virtio0 140000000-147ffffff : System RAM (virtio_mem) 148000000-14fffffff : System RAM (virtio_mem) 150000000-157ffffff : System RAM (virtio_mem) 158000000-15fffffff : System RAM (virtio_mem) 160000000-167ffffff : System RAM (virtio_mem) 168000000-16fffffff : System RAM (virtio_mem) 170000000-177ffffff : System RAM (virtio_mem) 178000000-17fffffff : System RAM (virtio_mem) 180000000-187ffffff : System RAM (virtio_mem) 188000000-18fffffff : System RAM (virtio_mem) 190000000-197ffffff : System RAM (virtio_mem) 198000000-19fffffff : System RAM (virtio_mem) 1a0000000-1a7ffffff : System RAM (virtio_mem) 1a8000000-1afffffff : System RAM (virtio_mem) 1b0000000-1b7ffffff : System RAM (virtio_mem) 1b8000000-1bfffffff : System RAM (virtio_mem) 3280000000-32ffffffff : PCI Bus 0000:00 With this patch, we get (/proc/iomem): [...] fffc0000-ffffffff : Reserved 100000000-13fffffff : System RAM 140000000-33fffffff : virtio0 140000000-1bfffffff : System RAM (virtio_mem) 3280000000-32ffffffff : PCI Bus 0000:00 Of course, with more hotplugged memory, it gets worse. When unplugging memory blocks again, try_remove_memory() (via offline_and_remove_memory()) will properly split the resource up again. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Baoquan He <bhe@redhat.com> Cc: Wei Yang <richardw.yang@linux.intel.com> Signed-off-by: David Hildenbrand <david@redhat.com> --- drivers/virtio/virtio_mem.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)