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authorVishal Verma <vishal.l.verma@intel.com>2024-01-24 12:03:50 -0800
committerAndrew Morton <akpm@linux-foundation.org>2024-02-22 10:24:40 -0800
commit73954d379efd176e9b011142c55aa8da93ac740a (patch)
tree0fc60f2c1a464365b1669c8bf4325ae5c87a53b3 /drivers/dax
parent42d9358252e5d055223487d9f653c2a2ac859a2a (diff)
dax: add a sysfs knob to control memmap_on_memory behavior
Add a sysfs knob for dax devices to control the memmap_on_memory setting if the dax device were to be hotplugged as system memory. The default memmap_on_memory setting for dax devices originating via pmem or hmem is set to 'false' - i.e. no memmap_on_memory semantics, to preserve legacy behavior. For dax devices via CXL, the default is on. The sysfs control allows the administrator to override the above defaults if needed. Link: https://lkml.kernel.org/r/20240124-vv-dax_abi-v7-5-20d16cb8d23d@intel.com Signed-off-by: Vishal Verma <vishal.l.verma@intel.com> Tested-by: Li Zhijian <lizhijian@fujitsu.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Huang, Ying <ying.huang@intel.com> Reviewed-by: Alison Schofield <alison.schofield@intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'drivers/dax')
-rw-r--r--drivers/dax/bus.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 0fd948a4443e..27c86d0ca711 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -1349,6 +1349,48 @@ static ssize_t numa_node_show(struct device *dev,
}
static DEVICE_ATTR_RO(numa_node);
+static ssize_t memmap_on_memory_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct dev_dax *dev_dax = to_dev_dax(dev);
+
+ return sysfs_emit(buf, "%d\n", dev_dax->memmap_on_memory);
+}
+
+static ssize_t memmap_on_memory_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t len)
+{
+ struct dev_dax *dev_dax = to_dev_dax(dev);
+ bool val;
+ int rc;
+
+ rc = kstrtobool(buf, &val);
+ if (rc)
+ return rc;
+
+ if (val == true && !mhp_supports_memmap_on_memory()) {
+ dev_dbg(dev, "memmap_on_memory is not available\n");
+ return -EOPNOTSUPP;
+ }
+
+ rc = down_write_killable(&dax_dev_rwsem);
+ if (rc)
+ return rc;
+
+ if (dev_dax->memmap_on_memory != val && dev->driver &&
+ to_dax_drv(dev->driver)->type == DAXDRV_KMEM_TYPE) {
+ up_write(&dax_dev_rwsem);
+ return -EBUSY;
+ }
+
+ dev_dax->memmap_on_memory = val;
+ up_write(&dax_dev_rwsem);
+
+ return len;
+}
+static DEVICE_ATTR_RW(memmap_on_memory);
+
static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
{
struct device *dev = container_of(kobj, struct device, kobj);
@@ -1375,6 +1417,7 @@ static struct attribute *dev_dax_attributes[] = {
&dev_attr_align.attr,
&dev_attr_resource.attr,
&dev_attr_numa_node.attr,
+ &dev_attr_memmap_on_memory.attr,
NULL,
};