memory-hotplug: remove redundant codes

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 <wency@cn.fujitsu.com> Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com> Reviewed-by: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Jiang Liu <jiang.liu@huawei.com> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Wu Jianguo <wujianguo@huawei.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memory-hotplug: remove redundant codes
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 <wency@cn.fujitsu.com> Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com> Reviewed-by: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Jiang Liu <jiang.liu@huawei.com> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Wu Jianguo <wujianguo@huawei.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Wen Congyang · Linus Torvalds
1 parent 6677e3eaf4
Showing 1 changed file with 82 additions and 47 deletions Side-by-side Diff
mm/memory_hotplug.c
@@ -1380,20 +1380,26 @@
 	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;
-	int return_on_error = 0;
-	int retry = 0;
  
-	start_pfn = PFN_DOWN(start);
-	end_pfn = start_pfn + PFN_DOWN(size);
-
-repeat:
 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 		section_nr = pfn_to_section_nr(pfn);
 		if (!present_section_nr(section_nr))
  
  
@@ -1410,22 +1416,76 @@
 		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;
+}
+
+/**
+ * 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 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;
 	}
  
  
@@ -1443,38 +1503,13 @@
 	 * memory blocks are offlined.
 	 */
  
-	mem = NULL;
-	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;
-		}
+	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;
...	...	@@ -1380,20 +1380,26 @@
1380	1380	return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
1381	1381	}
1382	1382
1383		-int remove_memory(u64 start, u64 size)
	1383	+/**
	1384	+ * walk_memory_range - walks through all mem sections in [start_pfn, end_pfn)
	1385	+ * @start_pfn: start pfn of the memory range
	1386	+ * @end_pfn: end pft of the memory range
	1387	+ * @arg: argument passed to func
	1388	+ * @func: callback for each memory section walked
	1389	+ *
	1390	+ * This function walks through all present mem sections in range
	1391	+ * [start_pfn, end_pfn) and call func on each mem section.
	1392	+ *
	1393	+ * Returns the return value of func.
	1394	+ */
	1395	+static int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
	1396	+ void arg, int (func)(struct memory_block , void ))
1384	1397	{
1385	1398	struct memory_block *mem = NULL;
1386	1399	struct mem_section *section;
1387		- unsigned long start_pfn, end_pfn;
1388	1400	unsigned long pfn, section_nr;
1389	1401	int ret;
1390		- int return_on_error = 0;
1391		- int retry = 0;
1392	1402
1393		- start_pfn = PFN_DOWN(start);
1394		- end_pfn = start_pfn + PFN_DOWN(size);
1395		-
1396		-repeat:
1397	1403	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
1398	1404	section_nr = pfn_to_section_nr(pfn);
1399	1405	if (!present_section_nr(section_nr))
1400	1406
1401	1407
...	...	@@ -1410,22 +1416,76 @@
1410	1416	if (!mem)
1411	1417	continue;
1412	1418
1413		- ret = offline_memory_block(mem);
	1419	+ ret = func(mem, arg);
1414	1420	if (ret) {
1415		- if (return_on_error) {
1416		- kobject_put(&mem->dev.kobj);
1417		- return ret;
1418		- } else {
1419		- retry = 1;
1420		- }
	1421	+ kobject_put(&mem->dev.kobj);
	1422	+ return ret;
1421	1423	}
1422	1424	}
1423	1425
1424	1426	if (mem)
1425	1427	kobject_put(&mem->dev.kobj);
1426	1428
1427		- if (retry) {
1428		- return_on_error = 1;
	1429	+ return 0;
	1430	+}
	1431	+
	1432	+/**
	1433	+ * offline_memory_block_cb - callback function for offlining memory block
	1434	+ * @mem: the memory block to be offlined
	1435	+ * @arg: buffer to hold error msg
	1436	+ *
	1437	+ * Always return 0, and put the error msg in arg if any.
	1438	+ */
	1439	+static int offline_memory_block_cb(struct memory_block mem, void arg)
	1440	+{
	1441	+ int *ret = arg;
	1442	+ int error = offline_memory_block(mem);
	1443	+
	1444	+ if (error != 0 && *ret == 0)
	1445	+ *ret = error;
	1446	+
	1447	+ return 0;
	1448	+}
	1449	+
	1450	+static int is_memblock_offlined_cb(struct memory_block mem, void arg)
	1451	+{
	1452	+ int ret = !is_memblock_offlined(mem);
	1453	+
	1454	+ if (unlikely(ret))
	1455	+ pr_warn("removing memory fails, because memory "
	1456	+ "[%#010llx-%#010llx] is onlined\n",
	1457	+ PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)),
	1458	+ PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1))-1);
	1459	+
	1460	+ return ret;
	1461	+}
	1462	+
	1463	+int remove_memory(u64 start, u64 size)
	1464	+{
	1465	+ unsigned long start_pfn, end_pfn;
	1466	+ int ret = 0;
	1467	+ int retry = 1;
	1468	+
	1469	+ start_pfn = PFN_DOWN(start);
	1470	+ end_pfn = start_pfn + PFN_DOWN(size);
	1471	+
	1472	+ /*
	1473	+ * When CONFIG_MEMCG is on, one memory block may be used by other
	1474	+ * blocks to store page cgroup when onlining pages. But we don't know
	1475	+ * in what order pages are onlined. So we iterate twice to offline
	1476	+ * memory:
	1477	+ * 1st iterate: offline every non primary memory block.
	1478	+ * 2nd iterate: offline primary (i.e. first added) memory block.
	1479	+ */
	1480	+repeat:
	1481	+ walk_memory_range(start_pfn, end_pfn, &ret,
	1482	+ offline_memory_block_cb);
	1483	+ if (ret) {
	1484	+ if (!retry)
	1485	+ return ret;
	1486	+
	1487	+ retry = 0;
	1488	+ ret = 0;
1429	1489	goto repeat;
1430	1490	}
1431	1491
1432	1492
...	...	@@ -1443,38 +1503,13 @@
1443	1503	* memory blocks are offlined.
1444	1504	*/
1445	1505
1446		- mem = NULL;
1447		- for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
1448		- section_nr = pfn_to_section_nr(pfn);
1449		- if (!present_section_nr(section_nr))
1450		- continue;
1451		-
1452		- section = __nr_to_section(section_nr);
1453		- /* same memblock? */
1454		- if (mem)
1455		- if ((section_nr >= mem->start_section_nr) &&
1456		- (section_nr <= mem->end_section_nr))
1457		- continue;
1458		-
1459		- mem = find_memory_block_hinted(section, mem);
1460		- if (!mem)
1461		- continue;
1462		-
1463		- ret = is_memblock_offlined(mem);
1464		- if (!ret) {
1465		- pr_warn("removing memory fails, because memory "
1466		- "[%#010llx-%#010llx] is onlined\n",
1467		- PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)),
1468		- PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1)) - 1);
1469		-
1470		- kobject_put(&mem->dev.kobj);
1471		- unlock_memory_hotplug();
1472		- return ret;
1473		- }
	1506	+ ret = walk_memory_range(start_pfn, end_pfn, NULL,
	1507	+ is_memblock_offlined_cb);
	1508	+ if (ret) {
	1509	+ unlock_memory_hotplug();
	1510	+ return ret;
1474	1511	}
1475	1512
1476		- if (mem)
1477		- kobject_put(&mem->dev.kobj);
1478	1513	unlock_memory_hotplug();
1479	1514
1480	1515	return 0;