dax/hmem: introduce dax_hmem.region_idle parameter

Introduce a new module parameter for dax_hmem which initializes all region
devices as free, rather than allocating a pagemap for the region by
default.

All hmem devices created with dax_hmem.region_idle=1 will have full
available size for creating dynamic dax devices.

Signed-off-by: Joao Martins <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Ben Skeggs <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Brice Goglin <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: David Airlie <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Hulk Robot <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Ira Weiny <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jason Yan <[email protected]>
Cc: Jeff Moyer <[email protected]>
Cc: "Jérôme Glisse" <[email protected]>
Cc: Jia He <[email protected]>
Cc: Jonathan Cameron <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: kernel test robot <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Pavel Tatashin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tom Lendacky <[email protected]>
Cc: Vishal Verma <[email protected]>
Cc: Vivek Goyal <[email protected]>
Cc: Wei Yang <[email protected]>
Cc: Will Deacon <[email protected]>
Link: https://lkml.kernel.org/r/159643106460.4062302.5868522341307530091.stgit@dwillia2-desk3.amr.corp.intel.com
Link: https://lore.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/160106119033.30709.11249962152222193448.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index 1a3347bb6143..1bf040dbc834 100644
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -5,6 +5,9 @@
 #include <linux/pfn_t.h>
 #include "../bus.h"
 
+static bool region_idle;
+module_param_named(region_idle, region_idle, bool, 0644);
+
 static int dax_hmem_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -30,7 +33,7 @@ static int dax_hmem_probe(struct platform_device *pdev)
 	data = (struct dev_dax_data) {
 		.dax_region = dax_region,
 		.id = -1,
-		.size = resource_size(res),
+		.size = region_idle ? 0 : resource_size(res),
 	};
 	dev_dax = devm_create_dev_dax(&data);
 	if (IS_ERR(dev_dax))