dax/kmem: allow kmem to add memory with memmap_on_memory

Large amounts of memory managed by the kmem driver may come in via CXL,
and it is often desirable to have the memmap for this memory on the new
memory itself.

Enroll kmem-managed memory for memmap_on_memory semantics if the dax
region originates via CXL.  For non-CXL dax regions, retain the existing
default behavior of hot adding without memmap_on_memory semantics.

Link: https://lkml.kernel.org/r/20231107-vv-kmem_memmap-v10-3-1253ec050ed0@intel.com
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Tested-by: Li Zhijian <lizhijian@fujitsu.com>	[cxl.kmem and nvdimm.kmem]
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Fan Ni <fan.ni@samsung.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 1659b787b65f55ba885b728597625c56af7aeff2..1ff1ab5fa105a60b2917ec1417156ff44e909074 100644 (file)
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -367,6 +367,7 @@ static ssize_t create_store(struct device *dev, struct device_attribute *attr,
                        .dax_region = dax_region,
                        .size = 0,
                        .id = -1,
+                       .memmap_on_memory = false,
                };
                struct dev_dax *dev_dax = devm_create_dev_dax(&data);
 
@@ -1400,6 +1401,8 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
        dev_dax->align = dax_region->align;
        ida_init(&dev_dax->ida);
 
+       dev_dax->memmap_on_memory = data->memmap_on_memory;
+
        inode = dax_inode(dax_dev);
        dev->devt = inode->i_rdev;
        dev->bus = &dax_bus_type;

diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
index 1ccd233601248505b2b29ab1cdeb101ed79abe4d..cbbf64443098c08d944878a190a0da69eccbfbf4 100644 (file)
--- a/drivers/dax/bus.h
+++ b/drivers/dax/bus.h
@@ -23,6 +23,7 @@ struct dev_dax_data {
        struct dev_pagemap *pgmap;
        resource_size_t size;
        int id;
+       bool memmap_on_memory;
 };
 
 struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data);

diff --git a/drivers/dax/cxl.c b/drivers/dax/cxl.c
index 8bc9d04034d65e210deabe8bc5b2d9d8dba03aa1..c696837ab23c95e3f2d9b58a18ffe3b3d3499537 100644 (file)
--- a/drivers/dax/cxl.c
+++ b/drivers/dax/cxl.c
@@ -26,6 +26,7 @@ static int cxl_dax_region_probe(struct device *dev)
                .dax_region = dax_region,
                .id = -1,
                .size = range_len(&cxlr_dax->hpa_range),
+               .memmap_on_memory = true,
        };
 
        return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));

diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
index 27cf2daaaa795ad9b8236b985d01aa0e6cea5c40..446617b73aeab2e6f5a2ec3ca4c3f740e1b3e719 100644 (file)
--- a/drivers/dax/dax-private.h
+++ b/drivers/dax/dax-private.h
@@ -70,6 +70,7 @@ struct dev_dax {
        struct ida ida;
        struct device dev;
        struct dev_pagemap *pgmap;
+       bool memmap_on_memory;
        int nr_range;
        struct dev_dax_range {
                unsigned long pgoff;

diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index 5d2ddef0f8f525b8651aa128887aeaa3b02da2aa..b9da69f926974f59eafadb9cb3e2ffd62639122f 100644 (file)
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -36,6 +36,7 @@ static int dax_hmem_probe(struct platform_device *pdev)
                .dax_region = dax_region,
                .id = -1,
                .size = region_idle ? 0 : range_len(&mri->range),
+               .memmap_on_memory = false,
        };
 
        return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));

diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 369c698b7706fb15e7ee259f5e635f7db0ff5527..42ee360cf4e3db86150b2f20db63bf626e601576 100644 (file)
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -12,6 +12,7 @@
 #include <linux/mm.h>
 #include <linux/mman.h>
 #include <linux/memory-tiers.h>
+#include <linux/memory_hotplug.h>
 #include "dax-private.h"
 #include "bus.h"
 
@@ -93,6 +94,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
        struct dax_kmem_data *data;
        struct memory_dev_type *mtype;
        int i, rc, mapped = 0;
+       mhp_t mhp_flags;
        int numa_node;
        int adist = MEMTIER_DEFAULT_DAX_ADISTANCE;
 
@@ -179,12 +181,16 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
                 */
                res->flags = IORESOURCE_SYSTEM_RAM;
 
+               mhp_flags = MHP_NID_IS_MGID;
+               if (dev_dax->memmap_on_memory)
+                       mhp_flags |= MHP_MEMMAP_ON_MEMORY;
+
                /*
                 * Ensure that future kexec'd kernels will not treat
                 * this as RAM automatically.
                 */
                rc = add_memory_driver_managed(data->mgid, range.start,
-                               range_len(&range), kmem_name, MHP_NID_IS_MGID);
+                               range_len(&range), kmem_name, mhp_flags);
 
                if (rc) {
                        dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",

diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
index ae0cb113a5d32e5ccaa025ff080b826d7cdfea94..f3c6c67b84128c549699a4a90282ff1542c2cbc5 100644 (file)
--- a/drivers/dax/pmem.c
+++ b/drivers/dax/pmem.c
@@ -63,6 +63,7 @@ static struct dev_dax *__dax_pmem_probe(struct device *dev)
                .id = id,
                .pgmap = &pgmap,
                .size = range_len(&range),
+               .memmap_on_memory = false,
        };
 
        return devm_create_dev_dax(&data);