This is the meat of this whole series.  When the "kmem" device's
probe function is called and we know we have a good persistent
memory device, hotplug the memory back into the main kernel.

Cc: Dan Williams <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: Ross Zwisler <[email protected]>
Cc: Vishal Verma <[email protected]>
Cc: Tom Lendacky <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Huang Ying <[email protected]>
Cc: Fengguang Wu <[email protected]>

---

 b/drivers/dax/kmem.c |   28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff -puN drivers/dax/kmem.c~dax-kmem-hotplug drivers/dax/kmem.c
--- a/drivers/dax/kmem.c~dax-kmem-hotplug       2018-10-22 13:12:24.069930387 
-0700
+++ b/drivers/dax/kmem.c        2018-10-22 13:12:24.072930387 -0700
@@ -55,10 +55,12 @@ static void dax_kmem_percpu_kill(void *d
 static int dax_kmem_probe(struct device *dev)
 {
        void *addr;
+       int numa_node;
        struct resource res;
        int rc, id, region_id;
        struct nd_pfn_sb *pfn_sb;
        struct dev_dax *dev_dax;
+       struct resource *new_res;
        struct dax_kmem *dax_kmem;
        struct nd_namespace_io *nsio;
        struct dax_region *dax_region;
@@ -86,13 +88,30 @@ static int dax_kmem_probe(struct device
 
        pfn_sb = nd_pfn->pfn_sb;
 
-       if (!devm_request_mem_region(dev, nsio->res.start,
-                               resource_size(&nsio->res),
-                               dev_name(&ndns->dev))) {
+       new_res = devm_request_mem_region(dev, nsio->res.start,
+                                         resource_size(&nsio->res),
+                                         "System RAM (pmem)");
+       if (!new_res) {
                dev_warn(dev, "could not reserve region %pR\n", &nsio->res);
                return -EBUSY;
        }
 
+       /*
+        * Set flags appropriate for System RAM.  Leave ..._BUSY clear
+        * so that add_memory() can add a child resource.
+        */
+       new_res->flags = IORESOURCE_SYSTEM_RAM;
+
+       numa_node = dev_to_node(dev);
+       if (numa_node < 0) {
+               pr_warn_once("bad numa_node: %d, forcing to 0\n", numa_node);
+               numa_node = 0;
+       }
+
+       rc = add_memory(numa_node, nsio->res.start, resource_size(&nsio->res));
+       if (rc)
+               return rc;
+
        dax_kmem->dev = dev;
        init_completion(&dax_kmem->cmp);
        rc = percpu_ref_init(&dax_kmem->ref, dax_kmem_percpu_release, 0,
@@ -106,6 +125,9 @@ static int dax_kmem_probe(struct device
                return rc;
 
        dax_kmem->pgmap.ref = &dax_kmem->ref;
+
+       dax_kmem->pgmap.res.name = "name_kmem_override2";
+
        addr = devm_memremap_pages(dev, &dax_kmem->pgmap);
        if (IS_ERR(addr))
                return PTR_ERR(addr);
_
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