[PATCH v3 5/6] device-dax: use fallback nid when numa_node is invalid

Jia He
2020-07-09T02:07:39Z

numa_off is set unconditionally at the end of dummy_numa_init(),
even with a fake numa node. ACPI detects node id as NUMA_NO_NODE(-1) in
acpi_map_pxm_to_node() because it regards numa_off as turning off the numa
node. Hence dev_dax->target_node is NUMA_NO_NODE on arm64 with fake numa.

Without this patch, pmem can't be probed as a RAM device on arm64 if SRAT table
isn't present:
$ndctl create-namespace -fe namespace0.0 --mode=devdax --map=dev -s 1g -a 64K
kmem dax0.0: rejecting DAX region [mem 0x240400000-0x2bfffffff] with invalid node: -1
kmem: probe of dax0.0 failed with error -22

This fixes it by using fallback memory_add_physaddr_to_nid() as nid.

Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Jia He <justin.he@arm.com>
---
drivers/dax/kmem.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 275aa5f87399..218f66057994 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -31,22 +31,23 @@ int dev_dax_kmem_probe(struct device *dev)
int numa_node;
int rc;

+ /* Hotplug starting at the beginning of the next block: */
+ kmem_start = ALIGN(res->start, memory_block_size_bytes());
+
/*
* Ensure good NUMA information for the persistent memory.
* Without this check, there is a risk that slow memory
* could be mixed in a node with faster memory, causing
- * unavoidable performance issues.
+ * unavoidable performance issues. Furthermore, fallback node
+ * id can be used when numa_node is invalid.
*/
numa_node = dev_dax->target_node;
if (numa_node < 0) {
- dev_warn(dev, "rejecting DAX region %pR with invalid node: %d\n",
- res, numa_node);
- return -EINVAL;
+ numa_node = memory_add_physaddr_to_nid(kmem_start);
+ dev_info(dev, "using nid %d for DAX region with undefined nid %pR\n",
+ numa_node, res);
}

- /* Hotplug starting at the beginning of the next block: */
- kmem_start = ALIGN(res->start, memory_block_size_bytes());
-
kmem_size = resource_size(res);
/* Adjust the size down to compensate for moving up kmem_start: */
kmem_size -= kmem_start - res->start;
@@ -100,15 +101,19 @@ static int dev_dax_kmem_remove(struct device *dev)
resource_size_t kmem_start = res->start;
resource_size_t kmem_size = resource_size(res);
const char *res_name = res->name;
+ int numa_node = dev_dax->target_node;
int rc;

+ if (numa_node < 0)
+ numa_node = memory_add_physaddr_to_nid(kmem_start);
+
/*
* 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);
+ rc = remove_memory(numa_node, kmem_start, kmem_size);
if (rc) {
any_hotremove_failed = true;
dev_err(dev,
--
2.17.1