3 files changed, 39 insertions, 5 deletions

diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
index 3107ce80e809..16850d5388ab 100644
--- a/drivers/dax/dax-private.h
+++ b/drivers/dax/dax-private.h
@@ -44,6 +44,7 @@ struct dax_region {
  * @dev - device core
  * @pgmap - pgmap for memmap setup / lifetime (driver owned)
  * @dax_mem_res: physical address range of hotadded DAX memory
+ * @dax_mem_name: name for hotadded DAX memory via add_memory_driver_managed()
  */
 struct dev_dax {
 	struct dax_region *region;
diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index 1af823b2fe6b..4c0af2eb7e19 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -377,6 +377,7 @@ static int dax_open(struct inode *inode, struct file *filp)
 	inode->i_mapping->a_ops = &dev_dax_aops;
 	filp->f_mapping = inode->i_mapping;
 	filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
+	filp->f_sb_err = file_sample_sb_err(filp);
 	filp->private_data = dev_dax;
 	inode->i_flags = S_DAX;
 
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 3d0a7e702c94..275aa5f87399 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -14,6 +14,11 @@
 #include "dax-private.h"
 #include "bus.h"
 
+/* Memory resource name used for add_memory_driver_managed(). */
+static const char *kmem_name;
+/* Set if any memory will remain added when the driver will be unloaded. */
+static bool any_hotremove_failed;
+
 int dev_dax_kmem_probe(struct device *dev)
 {
 	struct dev_dax *dev_dax = to_dev_dax(dev);
@@ -22,6 +27,7 @@ int dev_dax_kmem_probe(struct device *dev)
 	resource_size_t kmem_size;
 	resource_size_t kmem_end;
 	struct resource *new_res;
+	const char *new_res_name;
 	int numa_node;
 	int rc;
 
@@ -48,11 +54,16 @@ int dev_dax_kmem_probe(struct device *dev)
 	kmem_size &= ~(memory_block_size_bytes() - 1);
 	kmem_end = kmem_start + kmem_size;
 
-	/* Region is permanently reserved.  Hot-remove not yet implemented. */
-	new_res = request_mem_region(kmem_start, kmem_size, dev_name(dev));
+	new_res_name = kstrdup(dev_name(dev), GFP_KERNEL);
+	if (!new_res_name)
+		return -ENOMEM;
+
+	/* Region is permanently reserved if hotremove fails. */
+	new_res = request_mem_region(kmem_start, kmem_size, new_res_name);
 	if (!new_res) {
 		dev_warn(dev, "could not reserve region [%pa-%pa]\n",
 			 &kmem_start, &kmem_end);
+		kfree(new_res_name);
 		return -EBUSY;
 	}
 
@@ -63,12 +74,17 @@ int dev_dax_kmem_probe(struct device *dev)
 	 * unknown to us that will break add_memory() below.
 	 */
 	new_res->flags = IORESOURCE_SYSTEM_RAM;
-	new_res->name = dev_name(dev);
 
-	rc = add_memory(numa_node, new_res->start, resource_size(new_res));
+	/*
+	 * Ensure that future kexec'd kernels will not treat this as RAM
+	 * automatically.
+	 */
+	rc = add_memory_driver_managed(numa_node, new_res->start,
+				       resource_size(new_res), kmem_name);
 	if (rc) {
 		release_resource(new_res);
 		kfree(new_res);
+		kfree(new_res_name);
 		return rc;
 	}
 	dev_dax->dax_kmem_res = new_res;
@@ -83,6 +99,7 @@ static int dev_dax_kmem_remove(struct device *dev)
 	struct resource *res = dev_dax->dax_kmem_res;
 	resource_size_t kmem_start = res->start;
 	resource_size_t kmem_size = resource_size(res);
+	const char *res_name = res->name;
 	int rc;
 
 	/*
@@ -93,6 +110,7 @@ static int dev_dax_kmem_remove(struct device *dev)
 	 */
 	rc = remove_memory(dev_dax->target_node, kmem_start, kmem_size);
 	if (rc) {
+		any_hotremove_failed = true;
 		dev_err(dev,
 			"DAX region %pR cannot be hotremoved until the next reboot\n",
 			res);
@@ -102,6 +120,7 @@ static int dev_dax_kmem_remove(struct device *dev)
 	/* Release and free dax resources */
 	release_resource(res);
 	kfree(res);
+	kfree(res_name);
 	dev_dax->dax_kmem_res = NULL;
 
 	return 0;
@@ -116,6 +135,7 @@ static int dev_dax_kmem_remove(struct device *dev)
 	 * permanently pinned as reserved by the unreleased
 	 * request_mem_region().
 	 */
+	any_hotremove_failed = true;
 	return 0;
 }
 #endif /* CONFIG_MEMORY_HOTREMOVE */
@@ -129,12 +149,24 @@ static struct dax_device_driver device_dax_kmem_driver = {
 
 static int __init dax_kmem_init(void)
 {
-	return dax_driver_register(&device_dax_kmem_driver);
+	int rc;
+
+	/* Resource name is permanently allocated if any hotremove fails. */
+	kmem_name = kstrdup_const("System RAM (kmem)", GFP_KERNEL);
+	if (!kmem_name)
+		return -ENOMEM;
+
+	rc = dax_driver_register(&device_dax_kmem_driver);
+	if (rc)
+		kfree_const(kmem_name);
+	return rc;
 }
 
 static void __exit dax_kmem_exit(void)
 {
 	dax_driver_unregister(&device_dax_kmem_driver);
+	if (!any_hotremove_failed)
+		kfree_const(kmem_name);
 }
 
 MODULE_AUTHOR("Intel Corporation");