Hi Kamezawa-san,

Thanks for the reviewing. Please see below. :)

On 12/26/2012 11:20 AM, Kamezawa Hiroyuki wrote:

(2012/12/24 21:09), Tang Chen wrote:

quoted

From: Wen Congyang<redacted>

offlining memory blocks and checking whether memory blocks are offlined
are very similar. This patch introduces a new function to remove
redundant codes.

Signed-off-by: Wen Congyang<redacted>
---
   mm/memory_hotplug.c |  101 ++++++++++++++++++++++++++++-----------------------
   1 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index d43d97b..dbb04d8 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c

@@ -1381,20 +1381,14 @@ 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)

please add explanation of this function here. If (*func) returns val other than 0,
this function will fail and returns callback's return value...right ?

Yes, it will always return the func()'s return value. I'll add the
comment here. :)

quoted

+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;
-	int return_on_error = 0;
-	int retry = 0;
-
-	start_pfn = PFN_DOWN(start);
-	end_pfn = start_pfn + PFN_DOWN(size);

-repeat:

Shouldn't we check lock is held here ? (VM_BUG_ON(!mutex_is_locked(&mem_hotplug_mutex);

Well, I think, after applying this patch, walk_memory_range() will be
a separated function. And it can be used somewhere else where we don't
hold this lock. But for now, we can do this check.  :)

quoted

   	for (pfn = start_pfn; pfn<  end_pfn; pfn += PAGES_PER_SECTION) {
   		section_nr = pfn_to_section_nr(pfn);
   		if (!present_section_nr(section_nr))

@@ -1411,22 +1405,61 @@ repeat:
   		if (!mem)
   			continue;

-		ret = offline_memory_block(mem);
+		ret = func(mem, arg);
   		if (ret) {
-			if (return_on_error) {
-				kobject_put(&mem->dev.kobj);
-				return ret;
-			} else {
-				retry = 1;
-			}
+			kobject_put(&mem->dev.kobj);
+			return ret;
   		}
   	}

   	if (mem)
   		kobject_put(&mem->dev.kobj);

-	if (retry) {
-		return_on_error = 1;
+	return 0;
+}
+
+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;

Always returns 0 and run through all mem blocks for scan-and-retry, right ?
You need explanation here !

Yes, I'll add the comment. :)

quoted

+}
+
+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 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);
+
+repeat:

please explan why you repeat here .

This repeat is add in patch1. It aims to solve the problem we were
talking about in patch1. I'll add the comment here. :)

quoted

+	walk_memory_range(start_pfn, end_pfn,&ret,
+			  offline_memory_block_cb);
+	if (ret) {
+		if (!retry)
+			return ret;
+
+		retry = 0;
+		ret = 0;
   		goto repeat;
   	}

@@ -1444,37 +1477,13 @@ repeat:
   	 * memory blocks are offlined.
   	 */

-	for (pfn = start_pfn; pfn<  end_pfn; pfn += PAGES_PER_SECTION) {
-		section_nr = pfn_to_section_nr(pfn);
-		if (!present_section_nr(section_nr))
-			continue;
-
-		section = __nr_to_section(section_nr);
-		/* same memblock? */
-		if (mem)
-			if ((section_nr>= mem->start_section_nr)&&
-			    (section_nr<= mem->end_section_nr))
-				continue;
-
-		mem = find_memory_block_hinted(section, mem);
-		if (!mem)
-			continue;
-
-		ret = is_memblock_offlined(mem);
-		if (!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);
-
-			kobject_put(&mem->dev.kobj);
-			unlock_memory_hotplug();
-			return ret;
-		}

please explain what you do here. confirming all memory blocks are offlined
before returning 0 ....right ?

Will be added. :)

Thanks. :)

quoted

+	ret = walk_memory_range(start_pfn, end_pfn, NULL,
+				is_memblock_offlined_cb);
+	if (ret) {
+		unlock_memory_hotplug();
+		return ret;
   	}

-	if (mem)
-		kobject_put(&mem->dev.kobj);
   	unlock_memory_hotplug();

   	return 0;

Thanks,
-Kame