[RFC PATCH v2 2/3] device-dax: use fallback nid when numa_node is invalid
From: Jia He <hidden>
Date: 2020-07-07 05:59:44
Also in:
linux-mm, lkml, nvdimm
Subsystem:
device direct access (dax), the rest · Maintainers:
Dan Williams, Vishal Verma, Dave Jiang, Alison Schofield, Linus Torvalds
Previously, numa_off is set unconditionally at the end of dummy_numa_init(), even with a fake numa node. Then 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 <redacted> Signed-off-by: Jia He <redacted> --- I noticed that on powerpc memory_add_physaddr_to_nid is not exported for module driver. Set it to RFC due to this concern. drivers/dax/kmem.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 275aa5f87399..68e693ca6d59 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c@@ -28,20 +28,22 @@ int dev_dax_kmem_probe(struct device *dev) resource_size_t kmem_end; struct resource *new_res; const char *new_res_name; - int numa_node; + int numa_node, new_node; int rc; /* * 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. + * Without this check, there is a risk but not fatal that slow + * memory could be mixed in a node with faster memory, causing + * 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; + new_node = memory_add_physaddr_to_nid(kmem_start); + dev_info(dev, "changing nid from %d to %d for DAX region %pR\n", + numa_node, new_node, res); + numa_node = new_node; } /* Hotplug starting at the beginning of the next block: */
@@ -100,6 +102,7 @@ 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; /*
@@ -108,7 +111,10 @@ static int dev_dax_kmem_remove(struct device *dev) * 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 (numa_node < 0) + numa_node = memory_add_physaddr_to_nid(kmem_start); + + rc = remove_memory(numa_node, kmem_start, kmem_size); if (rc) { any_hotremove_failed = true; dev_err(dev,
--
2.17.1
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