Re: [linux-next:master] BUILD REGRESSION 3a00d3dfd4b68b208ecd5405e676d06c8ad6bb63

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 26 Aug 2020 17:13:12 +0100 Joao Martins <joao.m.martins@oracle.com> wrote:

> This should have been:

Thanks.

> 
> And also the MEMORY_HOTPLUG=n and ACPI=n build issues that Randy/you fixed which are
> introduced by this series too. Just to confirm: I should add up all these fixes and respin
> the series right? Or should I follow-up the first one on top of what you've already staged
> in -mm tree?

That's OK, I've been scooping up the fixes.

https://ozlabs.org/~akpm/mmots/broken-out/mm-memory_hotplug-introduce-default-phys_to_target_node-implementation-fix.patch

https://ozlabs.org/~akpm/mmots/broken-out/device-dax-make-align-a-per-device-property-fix.patch

and this one,

From: Joao Martins <joao.m.martins@oracle.com>
Subject: device-dax-add-dis-contiguous-resource-support-fix

kfree only with nr_range == 0, while also avoiding the leakage of @ranges
(from krealloc success case with nr_ranges > 0) without the null deref
that this introduces.

Link: https://lkml.kernel.org/r/6d57acf7-63cf-168d-f68e-67d88832f10f@oracle.com
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/dax/bus.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/drivers/dax/bus.c~device-dax-add-dis-contiguous-resource-support-fix
+++ a/drivers/dax/bus.c
@@ -607,13 +607,16 @@ static int alloc_dev_dax_range(struct de
 		return -ENOMEM;
 
 	alloc = __request_region(res, start, size, dev_name(dev), 0);
-	if (!alloc && !dev_dax->nr_range) {
+	if (!alloc) {
 		/*
-		 * If we adjusted an existing @ranges leave it alone,
-		 * but if this was an empty set of ranges nothing else
+		 * If this was an empty set of ranges nothing else
 		 * will release @ranges, so do it now.
 		 */
-		kfree(ranges);
+		if (!dev_dax->nr_range) {
+			kfree(ranges);
+			ranges = NULL;
+		}
+		dev_dax->ranges = ranges;
 		return -ENOMEM;
 	}
 
_