1 files changed, 111 insertions, 13 deletions

diff --git a/mm/memblock.c b/mm/memblock.c
index 0ac412a0a7ee..53e477bb5558 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -20,6 +20,8 @@
 #include <linux/seq_file.h>
 #include <linux/memblock.h>
 
+#include <asm-generic/sections.h>
+
 static struct memblock_region memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
 static struct memblock_region memblock_reserved_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
 
@@ -32,6 +34,7 @@ struct memblock memblock __initdata_memblock = {
         .reserved.cnt           = 1,    /* empty dummy entry */
         .reserved.max           = INIT_MEMBLOCK_REGIONS,
 
+        .bottom_up              = false,
         .current_limit          = MEMBLOCK_ALLOC_ANYWHERE,
 };
 
@@ -82,6 +85,73 @@ static long __init_memblock memblock_overlaps_region(struct memblock_type *type,
         return (i < type->cnt) ? i : -1;
 }
 
+/*
+ * __memblock_find_range_bottom_up - find free area utility in bottom-up
+ * @start: start of candidate range
+ * @end: end of candidate range, can be %MEMBLOCK_ALLOC_{ANYWHERE|ACCESSIBLE}
+ * @size: size of free area to find
+ * @align: alignment of free area to find
+ * @nid: nid of the free area to find, %MAX_NUMNODES for any node
+ *
+ * Utility called from memblock_find_in_range_node(), find free area bottom-up.
+ *
+ * RETURNS:
+ * Found address on success, 0 on failure.
+ */
+static phys_addr_t __init_memblock
+__memblock_find_range_bottom_up(phys_addr_t start, phys_addr_t end,
+                                phys_addr_t size, phys_addr_t align, int nid)
+{
+        phys_addr_t this_start, this_end, cand;
+        u64 i;
+
+        for_each_free_mem_range(i, nid, &this_start, &this_end, NULL) {
+                this_start = clamp(this_start, start, end);
+                this_end = clamp(this_end, start, end);
+
+                cand = round_up(this_start, align);
+                if (cand < this_end && this_end - cand >= size)
+                        return cand;
+        }
+
+        return 0;
+}
+
+/**
+ * __memblock_find_range_top_down - find free area utility, in top-down
+ * @start: start of candidate range
+ * @end: end of candidate range, can be %MEMBLOCK_ALLOC_{ANYWHERE|ACCESSIBLE}
+ * @size: size of free area to find
+ * @align: alignment of free area to find
+ * @nid: nid of the free area to find, %MAX_NUMNODES for any node
+ *
+ * Utility called from memblock_find_in_range_node(), find free area top-down.
+ *
+ * RETURNS:
+ * Found address on success, 0 on failure.
+ */
+static phys_addr_t __init_memblock
+__memblock_find_range_top_down(phys_addr_t start, phys_addr_t end,
+                               phys_addr_t size, phys_addr_t align, int nid)
+{
+        phys_addr_t this_start, this_end, cand;
+        u64 i;
+
+        for_each_free_mem_range_reverse(i, nid, &this_start, &this_end, NULL) {
+                this_start = clamp(this_start, start, end);
+                this_end = clamp(this_end, start, end);
+
+                if (this_end < size)
+                        continue;
+
+                cand = round_down(this_end - size, align);
+                if (cand >= this_start)
+                        return cand;
+        }
+
+        return 0;
+}
+
 /**
  * memblock_find_in_range_node - find free area in given range and node
  * @start: start of candidate range
@@ -92,15 +162,23 @@ static long __init_memblock memblock_overlaps_region(struct memblock_type *type,
  *
  * Find @size free area aligned to @align in the specified range and node.
  *
+ * When allocation direction is bottom-up, the @start should be greater
+ * than the end of the kernel image. Otherwise, it will be trimmed. The
+ * reason is that we want the bottom-up allocation just near the kernel
+ * image so it is highly likely that the allocated memory and the kernel
+ * will reside in the same node.
+ *
+ * If bottom-up allocation failed, will try to allocate memory top-down.
+ *
  * RETURNS:
- * Found address on success, %0 on failure.
+ * Found address on success, 0 on failure.
  */
 phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t start,
                                         phys_addr_t end, phys_addr_t size,
                                         phys_addr_t align, int nid)
 {
-        phys_addr_t this_start, this_end, cand;
-        u64 i;
+        int ret;
+        phys_addr_t kernel_end;
 
         /* pump up @end */
         if (end == MEMBLOCK_ALLOC_ACCESSIBLE)
@@ -109,19 +187,39 @@ phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t start,
         /* avoid allocating the first page */
         start = max_t(phys_addr_t, start, PAGE_SIZE);
         end = max(start, end);
+        kernel_end = __pa_symbol(_end);
 
-        for_each_free_mem_range_reverse(i, nid, &this_start, &this_end, NULL) {
-                this_start = clamp(this_start, start, end);
-                this_end = clamp(this_end, start, end);
+        /*
+         * try bottom-up allocation only when bottom-up mode
+         * is set and @end is above the kernel image.
+         */
+        if (memblock_bottom_up() && end > kernel_end) {
+                phys_addr_t bottom_up_start;
 
-                if (this_end < size)
-                        continue;
+                /* make sure we will allocate above the kernel */
+                bottom_up_start = max(start, kernel_end);
 
-                cand = round_down(this_end - size, align);
-                if (cand >= this_start)
-                        return cand;
+                /* ok, try bottom-up allocation first */
+                ret = __memblock_find_range_bottom_up(bottom_up_start, end,
+                                                      size, align, nid);
+                if (ret)
+                        return ret;
+
+                /*
+                 * we always limit bottom-up allocation above the kernel,
+                 * but top-down allocation doesn't have the limit, so
+                 * retrying top-down allocation may succeed when bottom-up
+                 * allocation failed.
+                 *
+                 * bottom-up allocation is expected to be fail very rarely,
+                 * so we use WARN_ONCE() here to see the stack trace if
+                 * fail happens.
+                 */
+                WARN_ONCE(1, "memblock: bottom-up allocation failed, "
+                             "memory hotunplug may be affected\n");
         }
-        return 0;
+
+        return __memblock_find_range_top_down(start, end, size, align, nid);
 }
 
 /**
@@ -134,7 +232,7 @@ phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t start,
  * Find @size free area aligned to @align in the specified range.
  *
  * RETURNS:
- * Found address on success, %0 on failure.
+ * Found address on success, 0 on failure.
  */
 phys_addr_t __init_memblock memblock_find_in_range(phys_addr_t start,
                                         phys_addr_t end, phys_addr_t size,