1 files changed, 37 insertions, 9 deletions

diff --git a/mm/sparse.c b/mm/sparse.c
index eb188eb6b82d..2ea8b3dbd0df 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -381,6 +381,7 @@ static void __init sparse_early_usemaps_alloc_node(void *data,
         unsigned long pnum;
         unsigned long **usemap_map = (unsigned long **)data;
         int size = usemap_size();
+        int nr_consumed_maps = 0;
 
         usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nodeid),
                                                           size * usemap_count);
@@ -392,9 +393,10 @@ static void __init sparse_early_usemaps_alloc_node(void *data,
         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
                 if (!present_section_nr(pnum))
                         continue;
-                usemap_map[pnum] = usemap;
+                usemap_map[nr_consumed_maps] = usemap;
                 usemap += size;
-                check_usemap_section_nr(nodeid, usemap_map[pnum]);
+                check_usemap_section_nr(nodeid, usemap_map[nr_consumed_maps]);
+                nr_consumed_maps++;
         }
 }
 
@@ -419,29 +421,34 @@ void __init sparse_mem_maps_populate_node(struct page **map_map,
         void *map;
         unsigned long pnum;
         unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
+        int nr_consumed_maps;
 
         size = PAGE_ALIGN(size);
         map = memblock_virt_alloc_try_nid_raw(size * map_count,
                                               PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
                                               BOOTMEM_ALLOC_ACCESSIBLE, nodeid);
         if (map) {
+                nr_consumed_maps = 0;
                 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
                         if (!present_section_nr(pnum))
                                 continue;
-                        map_map[pnum] = map;
+                        map_map[nr_consumed_maps] = map;
                         map += size;
+                        nr_consumed_maps++;
                 }
                 return;
         }
 
         /* fallback */
+        nr_consumed_maps = 0;
         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
                 struct mem_section *ms;
 
                 if (!present_section_nr(pnum))
                         continue;
-                map_map[pnum] = sparse_mem_map_populate(pnum, nodeid, NULL);
-                if (map_map[pnum])
+                map_map[nr_consumed_maps] =
+                                sparse_mem_map_populate(pnum, nodeid, NULL);
+                if (map_map[nr_consumed_maps++])
                         continue;
                 ms = __nr_to_section(pnum);
                 pr_err("%s: sparsemem memory map backing failed some memory will not be available\n",
@@ -521,6 +528,7 @@ static void __init alloc_usemap_and_memmap(void (*alloc_func)
                 /* new start, update count etc*/
                 nodeid_begin = nodeid;
                 pnum_begin = pnum;
+                data += map_count * data_unit_size;
                 map_count = 1;
         }
         /* ok, last chunk */
@@ -539,6 +547,7 @@ void __init sparse_init(void)
         unsigned long *usemap;
         unsigned long **usemap_map;
         int size;
+        int nr_consumed_maps = 0;
 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
         int size2;
         struct page **map_map;
@@ -561,7 +570,7 @@ void __init sparse_init(void)
          * powerpc need to call sparse_init_one_section right after each
          * sparse_early_mem_map_alloc, so allocate usemap_map at first.
          */
-        size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
+        size = sizeof(unsigned long *) * nr_present_sections;
         usemap_map = memblock_virt_alloc(size, 0);
         if (!usemap_map)
                 panic("can not allocate usemap_map\n");
@@ -570,7 +579,7 @@ void __init sparse_init(void)
                                 sizeof(usemap_map[0]));
 
 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
-        size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
+        size2 = sizeof(struct page *) * nr_present_sections;
         map_map = memblock_virt_alloc(size2, 0);
         if (!map_map)
                 panic("can not allocate map_map\n");
@@ -579,27 +588,46 @@ void __init sparse_init(void)
                                 sizeof(map_map[0]));
 #endif
 
+        /*
+         * The number of present sections stored in nr_present_sections
+         * are kept the same since mem sections are marked as present in
+         * memory_present(). In this for loop, we need check which sections
+         * failed to allocate memmap or usemap, then clear its
+         * ->section_mem_map accordingly. During this process, we need
+         * increase 'nr_consumed_maps' whether its allocation of memmap
+         * or usemap failed or not, so that after we handle the i-th
+         * memory section, can get memmap and usemap of (i+1)-th section
+         * correctly.
+         */
         for_each_present_section_nr(0, pnum) {
                 struct mem_section *ms;
+
+                if (nr_consumed_maps >= nr_present_sections) {
+                        pr_err("nr_consumed_maps goes beyond nr_present_sections\n");
+                        break;
+                }
                 ms = __nr_to_section(pnum);
-                usemap = usemap_map[pnum];
+                usemap = usemap_map[nr_consumed_maps];
                 if (!usemap) {
                         ms->section_mem_map = 0;
+                        nr_consumed_maps++;
                         continue;
                 }
 
 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
-                map = map_map[pnum];
+                map = map_map[nr_consumed_maps];
 #else
                 map = sparse_early_mem_map_alloc(pnum);
 #endif
                 if (!map) {
                         ms->section_mem_map = 0;
+                        nr_consumed_maps++;
                         continue;
                 }
 
                 sparse_init_one_section(__nr_to_section(pnum), pnum, map,
                                                                 usemap);
+                nr_consumed_maps++;
         }
 
         vmemmap_populate_print_last();