[PATCH v4 9/9] mm/page_alloc: allow base for movablecore

[Doug Berger]

A Designated Movable Block can be created by including the base
address of the block when specifying a movablecore range on the
kernel command line.

Signed-off-by: Doug Berger <opendmb@xxxxxxxxx>
---
 .../admin-guide/kernel-parameters.txt         | 14 ++++++-
 mm/page_alloc.c                               | 38 ++++++++++++++++---
 2 files changed, 45 insertions(+), 7 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 6221a1d057dd..5e3bf6e0a264 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3353,7 +3353,7 @@
 			reporting absolute coordinates, such as tablets
 
 	movablecore=	[KNL,X86,IA-64,PPC]
-			Format: nn[KMGTPE] | nn%
+			Format: nn[KMGTPE] | nn[KMGTPE]@ss[KMGTPE] | nn%
 			This parameter is the complement to kernelcore=, it
 			specifies the amount of memory used for migratable
 			allocations.  If both kernelcore and movablecore is
@@ -3363,6 +3363,18 @@
 			that the amount of memory usable for all allocations
 			is not too small.
 
+			If @ss[KMGTPE] is included, memory within the region
+			from ss to ss+nn will be designated as a movable block
+			and included in ZONE_MOVABLE. Designated Movable Blocks
+			must be aligned to pageblock_order. Designated Movable
+			Blocks take priority over values of kernelcore= and are
+			considered part of any memory specified by more general
+			movablecore= values.
+			Multiple Designated Movable Blocks may be specified,
+			comma delimited.
+			Example:
+				movablecore=100M@2G,100M@3G,1G@1024G
+
 	movable_node	[KNL] Boot-time switch to make hotplugable memory
 			NUMA nodes to be movable. This means that the memory
 			of such nodes will be usable only for movable
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d4358d19d5a1..cb3c55acf7de 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8504,9 +8504,9 @@ void __init free_area_init(unsigned long *max_zone_pfn)
 }
 
 static int __init cmdline_parse_core(char *p, unsigned long *core,
-				     unsigned long *percent)
+				     unsigned long *percent, bool movable)
 {
-	unsigned long long coremem;
+	unsigned long long coremem, address;
 	char *endptr;
 
 	if (!p)
@@ -8521,6 +8521,17 @@ static int __init cmdline_parse_core(char *p, unsigned long *core,
 		*percent = coremem;
 	} else {
 		coremem = memparse(p, &p);
+		if (movable && *p == '@') {
+			address = memparse(++p, &p);
+			if (*p != '\0' ||
+			    !memblock_is_region_memory(address, coremem) ||
+			    memblock_is_region_reserved(address, coremem))
+				return -EINVAL;
+			memblock_reserve(address, coremem);
+			return dmb_reserve(address, coremem, NULL);
+		} else if (*p != '\0') {
+			return -EINVAL;
+		}
 		/* Paranoid check that UL is enough for the coremem value */
 		WARN_ON((coremem >> PAGE_SHIFT) > ULONG_MAX);
 
@@ -8543,17 +8554,32 @@ static int __init cmdline_parse_kernelcore(char *p)
 	}
 
 	return cmdline_parse_core(p, &required_kernelcore,
-				  &required_kernelcore_percent);
+				  &required_kernelcore_percent, false);
 }
 
 /*
  * movablecore=size sets the amount of memory for use for allocations that
- * can be reclaimed or migrated.
+ * can be reclaimed or migrated. movablecore=size@base defines a Designated
+ * Movable Block.
  */
 static int __init cmdline_parse_movablecore(char *p)
 {
-	return cmdline_parse_core(p, &required_movablecore,
-				  &required_movablecore_percent);
+	int ret = -EINVAL;
+
+	while (p) {
+		char *k = strchr(p, ',');
+
+		if (k)
+			*k++ = 0;
+
+		ret = cmdline_parse_core(p, &required_movablecore,
+					 &required_movablecore_percent, true);
+		if (ret)
+			break;
+		p = k;
+	}
+
+	return ret;
 }
 
 early_param("kernelcore", cmdline_parse_kernelcore);
-- 
2.34.1