memblock: Make MEMBLOCK_ERROR be 0

And ensure we don't hand out 0 as a valid allocation. We put the
low limit at PAGE_SIZE arbitrarily.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

2 files changed, 7 insertions, 1 deletions

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 1a9c29cc92fa..dfa64494ced1 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -19,7 +19,7 @@
 #include <asm/memblock.h>
 
 #define INIT_MEMBLOCK_REGIONS   128
-#define MEMBLOCK_ERROR          (~(phys_addr_t)0)
+#define MEMBLOCK_ERROR          0
 
 struct memblock_region {
         phys_addr_t base;
diff --git a/mm/memblock.c b/mm/memblock.c
index 85cfa1d3ab28..cb520df2a414 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -105,6 +105,12 @@ static phys_addr_t __init memblock_find_region(phys_addr_t start, phys_addr_t en
         phys_addr_t base, res_base;
         long j;
 
+        /* Prevent allocations returning 0 as it's also used to
+         * indicate an allocation failure
+         */
+        if (start == 0)
+                start = PAGE_SIZE;
+
         base = memblock_align_down((end - size), align);
         while (start <= base) {
                 j = memblock_overlaps_region(&memblock.reserved, base, size);