[PATCH 1/6] nvdimm/region: Fix default alignment for small regions

[Dan Williams]

In preparation for removing BLK aperture support the NVDIMM unit tests
discovered that the default alignment can be set higher than the
capacity of the region. Fall back to PAGE_SIZE in that case.

Given this has not been seen in the wild, elide notifying -stable.

Fixes: 2522afb86a8c ("libnvdimm/region: Introduce an 'align' attribute")
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
 drivers/nvdimm/region_devs.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index 9ccf3d608799..70ad891a76ba 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1025,6 +1025,9 @@ static unsigned long default_align(struct nd_region 
*nd_region)
                }
        }
 
+       if (nd_region->ndr_size < MEMREMAP_COMPAT_ALIGN_MAX)
+               align = PAGE_SIZE;
+
        mappings = max_t(u16, 1, nd_region->ndr_mappings);
        div_u64_rem(align, mappings, &remainder);
        if (remainder)