memory hotplug: rearrange memory hotplug notifier

Current memory notifier has some defects yet.  (Fortunately, nothing uses
it.) This patch is to fix and rearrange for them.

  - Add information of start_pfn, nr_pages, and node id if node status is
    changes from/to memoryless node for callback functions.
    Callbacks can't do anything without those information.
  - Add notification going-online status.
    It is necessary for creating per node structure before the node's
    pages are available.
  - Move GOING_OFFLINE status notification after page isolation.
    It is good place for return memory like cache for callback,
    because returned page is not used again.
  - Make CANCEL events for rollingback when error occurs.
  - Delete MEM_MAPPING_INVALID notification. It will be not used.
  - Fix compile error of (un)register_memory_notifier().

Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 61 insertions, 23 deletions

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index c41d0728efe2..7868707c7eda 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -137,7 +137,7 @@ static ssize_t show_mem_state(struct sys_device *dev, char *buf)
         return len;
 }
 
-static inline int memory_notify(unsigned long val, void *v)
+int memory_notify(unsigned long val, void *v)
 {
         return blocking_notifier_call_chain(&memory_chain, val, v);
 }
@@ -183,7 +183,6 @@ memory_block_action(struct memory_block *mem, unsigned long action)
                         break;
                 case MEM_OFFLINE:
                         mem->state = MEM_GOING_OFFLINE;
-                        memory_notify(MEM_GOING_OFFLINE, NULL);
                         start_paddr = page_to_pfn(first_page) << PAGE_SHIFT;
                         ret = remove_memory(start_paddr,
                                             PAGES_PER_SECTION << PAGE_SHIFT);
@@ -191,7 +190,6 @@ memory_block_action(struct memory_block *mem, unsigned long action)
                                 mem->state = old_state;
                                 break;
                         }
-                        memory_notify(MEM_MAPPING_INVALID, NULL);
                         break;
                 default:
                         printk(KERN_WARNING "%s(%p, %ld) unknown action: %ld\n",
@@ -199,11 +197,6 @@ memory_block_action(struct memory_block *mem, unsigned long action)
                         WARN_ON(1);
                         ret = -EINVAL;
         }
-        /*
-         * For now, only notify on successful memory operations
-         */
-        if (!ret)
-                memory_notify(action, NULL);
 
         return ret;
 }
diff --git a/include/linux/memory.h b/include/linux/memory.h
index 654ef5544878..ec376e482abb 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -41,18 +41,15 @@ struct memory_block {
 #define MEM_ONLINE              (1<<0) /* exposed to userspace */
 #define MEM_GOING_OFFLINE       (1<<1) /* exposed to userspace */
 #define MEM_OFFLINE             (1<<2) /* exposed to userspace */
+#define MEM_GOING_ONLINE        (1<<3)
+#define MEM_CANCEL_ONLINE       (1<<4)
+#define MEM_CANCEL_OFFLINE      (1<<5)
 
-/*
- * All of these states are currently kernel-internal for notifying
- * kernel components and architectures.
- *
- * For MEM_MAPPING_INVALID, all notifier chains with priority >0
- * are called before pfn_to_page() becomes invalid.  The priority=0
- * entry is reserved for the function that actually makes
- * pfn_to_page() stop working.  Any notifiers that want to be called
- * after that should have priority <0.
- */
-#define MEM_MAPPING_INVALID     (1<<3)
+struct memory_notify {
+        unsigned long start_pfn;
+        unsigned long nr_pages;
+        int status_change_nid;
+};
 
 struct notifier_block;
 struct mem_section;
@@ -69,12 +66,18 @@ static inline int register_memory_notifier(struct notifier_block *nb)
 static inline void unregister_memory_notifier(struct notifier_block *nb)
 {
 }
+static inline int memory_notify(unsigned long val, void *v)
+{
+        return 0;
+}
 #else
+extern int register_memory_notifier(struct notifier_block *nb);
+extern void unregister_memory_notifier(struct notifier_block *nb);
 extern int register_new_memory(struct mem_section *);
 extern int unregister_memory_section(struct mem_section *);
 extern int memory_dev_init(void);
 extern int remove_memory_block(unsigned long, struct mem_section *, int);
-
+extern int memory_notify(unsigned long val, void *v);
 #define CONFIG_MEM_BLOCK_SIZE   (PAGES_PER_SECTION<<PAGE_SHIFT)
 
 
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 1833879f8438..3a47871a29d9 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -187,7 +187,24 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
         unsigned long onlined_pages = 0;
         struct zone *zone;
         int need_zonelists_rebuild = 0;
+        int nid;
+        int ret;
+        struct memory_notify arg;
+
+        arg.start_pfn = pfn;
+        arg.nr_pages = nr_pages;
+        arg.status_change_nid = -1;
+
+        nid = page_to_nid(pfn_to_page(pfn));
+        if (node_present_pages(nid) == 0)
+                arg.status_change_nid = nid;
 
+        ret = memory_notify(MEM_GOING_ONLINE, &arg);
+        ret = notifier_to_errno(ret);
+        if (ret) {
+                memory_notify(MEM_CANCEL_ONLINE, &arg);
+                return ret;
+        }
         /*
          * This doesn't need a lock to do pfn_to_page().
          * The section can't be removed here because of the
@@ -222,6 +239,10 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
                 build_all_zonelists();
         vm_total_pages = nr_free_pagecache_pages();
         writeback_set_ratelimit();
+
+        if (onlined_pages)
+                memory_notify(MEM_ONLINE, &arg);
+
         return 0;
 }
 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
@@ -467,8 +488,9 @@ int offline_pages(unsigned long start_pfn,
 {
         unsigned long pfn, nr_pages, expire;
         long offlined_pages;
-        int ret, drain, retry_max;
+        int ret, drain, retry_max, node;
         struct zone *zone;
+        struct memory_notify arg;
 
         BUG_ON(start_pfn >= end_pfn);
         /* at least, alignment against pageblock is necessary */
@@ -480,11 +502,27 @@ int offline_pages(unsigned long start_pfn,
            we assume this for now. .*/
         if (!test_pages_in_a_zone(start_pfn, end_pfn))
                 return -EINVAL;
+
+        zone = page_zone(pfn_to_page(start_pfn));
+        node = zone_to_nid(zone);
+        nr_pages = end_pfn - start_pfn;
+
         /* set above range as isolated */
         ret = start_isolate_page_range(start_pfn, end_pfn);
         if (ret)
                 return ret;
-        nr_pages = end_pfn - start_pfn;
+
+        arg.start_pfn = start_pfn;
+        arg.nr_pages = nr_pages;
+        arg.status_change_nid = -1;
+        if (nr_pages >= node_present_pages(node))
+                arg.status_change_nid = node;
+
+        ret = memory_notify(MEM_GOING_OFFLINE, &arg);
+        ret = notifier_to_errno(ret);
+        if (ret)
+                goto failed_removal;
+
         pfn = start_pfn;
         expire = jiffies + timeout;
         drain = 0;
@@ -539,20 +577,24 @@ repeat:
         /* reset pagetype flags */
         start_isolate_page_range(start_pfn, end_pfn);
         /* removal success */
-        zone = page_zone(pfn_to_page(start_pfn));
         zone->present_pages -= offlined_pages;
         zone->zone_pgdat->node_present_pages -= offlined_pages;
         totalram_pages -= offlined_pages;
         num_physpages -= offlined_pages;
+
         vm_total_pages = nr_free_pagecache_pages();
         writeback_set_ratelimit();
+
+        memory_notify(MEM_OFFLINE, &arg);
         return 0;
 
 failed_removal:
         printk(KERN_INFO "memory offlining %lx to %lx failed\n",
                 start_pfn, end_pfn);
+        memory_notify(MEM_CANCEL_OFFLINE, &arg);
         /* pushback to free area */
         undo_isolate_page_range(start_pfn, end_pfn);
+
         return ret;
 }
 #else