2 files changed, 43 insertions, 5 deletions

diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
index c915889d1769..6ccca3b890d6 100644
--- a/drivers/dax/dax-private.h
+++ b/drivers/dax/dax-private.h
@@ -43,6 +43,7 @@ struct dax_region {
  * @target_node: effective numa node if dev_dax memory range is onlined
  * @dev - device core
  * @pgmap - pgmap for memmap setup / lifetime (driver owned)
+ * @dax_mem_res: physical address range of hotadded DAX memory
  */
 struct dev_dax {
         struct dax_region *region;
@@ -50,6 +51,7 @@ struct dev_dax {
         int target_node;
         struct device dev;
         struct dev_pagemap pgmap;
+        struct resource *dax_kmem_res;
 };
 
 static inline struct dev_dax *to_dev_dax(struct device *dev)
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index a02318c6d28a..3d0a7e702c94 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -66,23 +66,59 @@ int dev_dax_kmem_probe(struct device *dev)
         new_res->name = dev_name(dev);
 
         rc = add_memory(numa_node, new_res->start, resource_size(new_res));
-        if (rc)
+        if (rc) {
+                release_resource(new_res);
+                kfree(new_res);
                 return rc;
+        }
+        dev_dax->dax_kmem_res = new_res;
 
         return 0;
 }
 
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static int dev_dax_kmem_remove(struct device *dev)
+{
+        struct dev_dax *dev_dax = to_dev_dax(dev);
+        struct resource *res = dev_dax->dax_kmem_res;
+        resource_size_t kmem_start = res->start;
+        resource_size_t kmem_size = resource_size(res);
+        int rc;
+
+        /*
+         * We have one shot for removing memory, if some memory blocks were not
+         * offline prior to calling this function remove_memory() will fail, and
+         * there is no way to hotremove this memory until reboot because device
+         * unbind will succeed even if we return failure.
+         */
+        rc = remove_memory(dev_dax->target_node, kmem_start, kmem_size);
+        if (rc) {
+                dev_err(dev,
+                        "DAX region %pR cannot be hotremoved until the next reboot\n",
+                        res);
+                return rc;
+        }
+
+        /* Release and free dax resources */
+        release_resource(res);
+        kfree(res);
+        dev_dax->dax_kmem_res = NULL;
+
+        return 0;
+}
+#else
 static int dev_dax_kmem_remove(struct device *dev)
 {
         /*
-         * Purposely leak the request_mem_region() for the device-dax
-         * range and return '0' to ->remove() attempts. The removal of
-         * the device from the driver always succeeds, but the region
-         * is permanently pinned as reserved by the unreleased
+         * Without hotremove purposely leak the request_mem_region() for the
+         * device-dax range and return '0' to ->remove() attempts. The removal
+         * of the device from the driver always succeeds, but the region is
+         * permanently pinned as reserved by the unreleased
          * request_mem_region().
          */
         return 0;
 }
+#endif /* CONFIG_MEMORY_HOTREMOVE */
 
 static struct dax_device_driver device_dax_kmem_driver = {
         .drv = {