Patch "MIPS: init: Ensure bootmem does not corrupt reserved memory" has been added to the 4.9-stable tree

@@ -153,6 +153,35 @@ void __init detect_memory_region(phys_ad
 	add_memory_region(start, size, BOOT_MEM_RAM);
 }
 
+bool __init memory_region_available(phys_addr_t start, phys_addr_t size)
+{
+	int i;
+	bool in_ram = false, free = true;
+
+	for (i = 0; i < boot_mem_map.nr_map; i++) {
+		phys_addr_t start_, end_;
+
+		start_ = boot_mem_map.map[i].addr;
+		end_ = boot_mem_map.map[i].addr + boot_mem_map.map[i].size;
+
+		switch (boot_mem_map.map[i].type) {
+		case BOOT_MEM_RAM:
+			if (start >= start_ && start + size <= end_)
+				in_ram = true;
+			break;
+		case BOOT_MEM_RESERVED:
+			if ((start >= start_ && start < end_) ||
+			    (start < start_ && start + size >= start_))
+				free = false;
+			break;
+		default:
+			continue;
+		}
+	}
+
+	return in_ram && free;
+}
+
 static void __init print_memory_map(void)
 {
 	int i;

@@ -332,11 +361,19 @@ static void __init bootmem_init(void)
 
 #else  /* !CONFIG_SGI_IP27 */
 
+static unsigned long __init bootmap_bytes(unsigned long pages)
+{
+	unsigned long bytes = DIV_ROUND_UP(pages, 8);
+
+	return ALIGN(bytes, sizeof(long));
+}
+
 static void __init bootmem_init(void)
 {
 	unsigned long reserved_end;
 	unsigned long mapstart = ~0UL;
 	unsigned long bootmap_size;
+	bool bootmap_valid = false;
 	int i;
 
 	/*

@@ -430,11 +467,42 @@ static void __init bootmem_init(void)
 #endif
 
 	/*
-	 * Initialize the boot-time allocator with low memory only.
+	 * check that mapstart doesn't overlap with any of
+	 * memory regions that have been reserved through eg. DTB
 	 */
-	bootmap_size = init_bootmem_node(NODE_DATA(0), mapstart,
-					 min_low_pfn, max_low_pfn);
+	bootmap_size = bootmap_bytes(max_low_pfn - min_low_pfn);
+
+	bootmap_valid = memory_region_available(PFN_PHYS(mapstart),
+						bootmap_size);
+	for (i = 0; i < boot_mem_map.nr_map && !bootmap_valid; i++) {
+		unsigned long mapstart_addr;
+
+		switch (boot_mem_map.map[i].type) {
+		case BOOT_MEM_RESERVED:
+			mapstart_addr = PFN_ALIGN(boot_mem_map.map[i].addr +
+						boot_mem_map.map[i].size);
+			if (PHYS_PFN(mapstart_addr) < mapstart)
+				break;
+
+			bootmap_valid = memory_region_available(mapstart_addr,
+								bootmap_size);
+			if (bootmap_valid)
+				mapstart = PHYS_PFN(mapstart_addr);
+			break;
+		default:
+			break;
+		}
+	}
 
+	if (!bootmap_valid)
+		panic("No memory area to place a bootmap bitmap");
+
+	/*
+	 * Initialize the boot-time allocator with low memory only.
+	 */
+	if (bootmap_size != init_bootmem_node(NODE_DATA(0), mapstart,
+					 min_low_pfn, max_low_pfn))
+		panic("Unexpected memory size required for bootmap");
 
 	for (i = 0; i < boot_mem_map.nr_map; i++) {
 		unsigned long start, end;