X-Git-Url: http://drtracing.org/?a=blobdiff_plain;ds=sidebyside;f=mm%2Fmemory_hotplug.c;h=942b43f6d7361aca8f8dd793f25d6604ed35e4b0;hb=24d335ca3606b610ec69c66a1e42760c96d89470;hp=d04ed87bfacbab59953859f9e860acae3f6335ab;hpb=f741656d646f7a5b56ba86765205b954237e7956;p=deliverable%2Flinux.git

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index d04ed87bfacb..942b43f6d736 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -901,8 +901,7 @@ error:
 	/* rollback pgdat allocation and others */
 	if (new_pgdat)
 		rollback_node_hotadd(nid, pgdat);
-	if (res)
-		release_memory_resource(res);
+	release_memory_resource(res);
 
 out:
 	unlock_memory_hotplug();
@@ -1381,17 +1380,26 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 	return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
 }
 
-int remove_memory(u64 start, u64 size)
+/**
+ * walk_memory_range - walks through all mem sections in [start_pfn, end_pfn)
+ * @start_pfn: start pfn of the memory range
+ * @end_pfn: end pft of the memory range
+ * @arg: argument passed to func
+ * @func: callback for each memory section walked
+ *
+ * This function walks through all present mem sections in range
+ * [start_pfn, end_pfn) and call func on each mem section.
+ *
+ * Returns the return value of func.
+ */
+static int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
+		void *arg, int (*func)(struct memory_block *, void *))
 {
 	struct memory_block *mem = NULL;
 	struct mem_section *section;
-	unsigned long start_pfn, end_pfn;
 	unsigned long pfn, section_nr;
 	int ret;
 
-	start_pfn = PFN_DOWN(start);
-	end_pfn = start_pfn + PFN_DOWN(size);
-
 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 		section_nr = pfn_to_section_nr(pfn);
 		if (!present_section_nr(section_nr))
@@ -1408,7 +1416,7 @@ int remove_memory(u64 start, u64 size)
 		if (!mem)
 			continue;
 
-		ret = offline_memory_block(mem);
+		ret = func(mem, arg);
 		if (ret) {
 			kobject_put(&mem->dev.kobj);
 			return ret;
@@ -1420,6 +1428,97 @@ int remove_memory(u64 start, u64 size)
 
 	return 0;
 }
+
+/**
+ * offline_memory_block_cb - callback function for offlining memory block
+ * @mem: the memory block to be offlined
+ * @arg: buffer to hold error msg
+ *
+ * Always return 0, and put the error msg in arg if any.
+ */
+static int offline_memory_block_cb(struct memory_block *mem, void *arg)
+{
+	int *ret = arg;
+	int error = offline_memory_block(mem);
+
+	if (error != 0 && *ret == 0)
+		*ret = error;
+
+	return 0;
+}
+
+static int is_memblock_offlined_cb(struct memory_block *mem, void *arg)
+{
+	int ret = !is_memblock_offlined(mem);
+
+	if (unlikely(ret))
+		pr_warn("removing memory fails, because memory "
+			"[%#010llx-%#010llx] is onlined\n",
+			PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)),
+			PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1))-1);
+
+	return ret;
+}
+
+int __ref remove_memory(u64 start, u64 size)
+{
+	unsigned long start_pfn, end_pfn;
+	int ret = 0;
+	int retry = 1;
+
+	start_pfn = PFN_DOWN(start);
+	end_pfn = start_pfn + PFN_DOWN(size);
+
+	/*
+	 * When CONFIG_MEMCG is on, one memory block may be used by other
+	 * blocks to store page cgroup when onlining pages. But we don't know
+	 * in what order pages are onlined. So we iterate twice to offline
+	 * memory:
+	 * 1st iterate: offline every non primary memory block.
+	 * 2nd iterate: offline primary (i.e. first added) memory block.
+	 */
+repeat:
+	walk_memory_range(start_pfn, end_pfn, &ret,
+			  offline_memory_block_cb);
+	if (ret) {
+		if (!retry)
+			return ret;
+
+		retry = 0;
+		ret = 0;
+		goto repeat;
+	}
+
+	lock_memory_hotplug();
+
+	/*
+	 * we have offlined all memory blocks like this:
+	 *   1. lock memory hotplug
+	 *   2. offline a memory block
+	 *   3. unlock memory hotplug
+	 *
+	 * repeat step1-3 to offline the memory block. All memory blocks
+	 * must be offlined before removing memory. But we don't hold the
+	 * lock in the whole operation. So we should check whether all
+	 * memory blocks are offlined.
+	 */
+
+	ret = walk_memory_range(start_pfn, end_pfn, NULL,
+				is_memblock_offlined_cb);
+	if (ret) {
+		unlock_memory_hotplug();
+		return ret;
+	}
+
+	/* remove memmap entry */
+	firmware_map_remove(start, start + size, "System RAM");
+
+	arch_remove_memory(start, size);
+
+	unlock_memory_hotplug();
+
+	return 0;
+}
 #else
 int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 {