From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Wed, 28 Jul 2010 05:25:10 +0000 (+1000)
Subject: memblock: Make MEMBLOCK_ERROR be 0
X-Git-Tag: firefly_0821_release~7613^2~3706^2~37
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=25818f0f28;p=firefly-linux-kernel-4.4.55.git

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>
---

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);