Commit 
480b6837aa57 "nvdimm: fix PHYS_PFN/PFN_PHYS mixup" identified
that we were passing an invalid address to devm_nvdimm_ioremap(). With
that fixed it exposed a bug in the memory reservation size for flush
hint tables.  Since we map a full page we need to mock a full page of
memory to back the flush hint table entries.
Cc: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
                        return -ENOMEM;
                sprintf(t->label[i], "label%d", i);
 
-               t->flush[i] = test_alloc(t, sizeof(u64) * NUM_HINTS,
+               t->flush[i] = test_alloc(t, max(PAGE_SIZE,
+                                       sizeof(u64) * NUM_HINTS),
                                &t->flush_dma[i]);
                if (!t->flush[i])
                        return -ENOMEM;