summaryrefslogtreecommitdiff
path: root/mm/memory_hotplug.c
diff options
context:
space:
mode:
Diffstat (limited to 'mm/memory_hotplug.c')
-rw-r--r--mm/memory_hotplug.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 1b6fe8ca71e6..489f235502db 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -31,6 +31,7 @@
#include <linux/firmware-map.h>
#include <linux/stop_machine.h>
#include <linux/hugetlb.h>
+#include <linux/memblock.h>
#include <asm/tlbflush.h>
@@ -1422,6 +1423,36 @@ static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
}
#endif /* CONFIG_MOVABLE_NODE */
+static int __init cmdline_parse_movable_node(char *p)
+{
+#ifdef CONFIG_MOVABLE_NODE
+ /*
+ * Memory used by the kernel cannot be hot-removed because Linux
+ * cannot migrate the kernel pages. When memory hotplug is
+ * enabled, we should prevent memblock from allocating memory
+ * for the kernel.
+ *
+ * ACPI SRAT records all hotpluggable memory ranges. But before
+ * SRAT is parsed, we don't know about it.
+ *
+ * The kernel image is loaded into memory at very early time. We
+ * cannot prevent this anyway. So on NUMA system, we set any
+ * node the kernel resides in as un-hotpluggable.
+ *
+ * Since on modern servers, one node could have double-digit
+ * gigabytes memory, we can assume the memory around the kernel
+ * image is also un-hotpluggable. So before SRAT is parsed, just
+ * allocate memory near the kernel image to try the best to keep
+ * the kernel away from hotpluggable memory.
+ */
+ memblock_set_bottom_up(true);
+#else
+ pr_warn("movable_node option not supported\n");
+#endif
+ return 0;
+}
+early_param("movable_node", cmdline_parse_movable_node);
+
/* check which state of node_states will be changed when offline memory */
static void node_states_check_changes_offline(unsigned long nr_pages,
struct zone *zone, struct memory_notify *arg)