memcg: allocate all page_cgroup at boot

Allocate all page_cgroup at boot and remove page_cgroup poitner from
struct page.  This patch adds an interface as

 struct page_cgroup *lookup_page_cgroup(struct page*)

All FLATMEM/DISCONTIGMEM/SPARSEMEM  and MEMORY_HOTPLUG is supported.

Remove page_cgroup pointer reduces the amount of memory by
 - 4 bytes per PAGE_SIZE.
 - 8 bytes per PAGE_SIZE
if memory controller is disabled. (even if configured.)

On usual 8GB x86-32 server, this saves 8MB of NORMAL_ZONE memory.
On my x86-64 server with 48GB of memory, this saves 96MB of memory.
I think this reduction makes sense.

By pre-allocation, kmalloc/kfree in charge/uncharge are removed.
This means
  - we're not necessary to be afraid of kmalloc faiulre.
    (this can happen because of gfp_mask type.)
  - we can avoid calling kmalloc/kfree.
  - we can avoid allocating tons of small objects which can be fragmented.
  - we can know what amount of memory will be used for this extra-lru handling.

I added printk message as

	"allocated %ld bytes of page_cgroup"
        "please try cgroup_disable=memory option if you don't want"

maybe enough informative for users.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 237 insertions, 0 deletions

diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
new file mode 100644
index 00000000000..5d86550701f
--- /dev/null
+++ b/mm/page_cgroup.c
@@ -0,0 +1,237 @@
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/bootmem.h>
+#include <linux/bit_spinlock.h>
+#include <linux/page_cgroup.h>
+#include <linux/hash.h>
+#include <linux/memory.h>
+
+static void __meminit
+__init_page_cgroup(struct page_cgroup *pc, unsigned long pfn)
+{
+	pc->flags = 0;
+	pc->mem_cgroup = NULL;
+	pc->page = pfn_to_page(pfn);
+}
+static unsigned long total_usage;
+
+#if !defined(CONFIG_SPARSEMEM)
+
+
+void __init pgdat_page_cgroup_init(struct pglist_data *pgdat)
+{
+	pgdat->node_page_cgroup = NULL;
+}
+
+struct page_cgroup *lookup_page_cgroup(struct page *page)
+{
+	unsigned long pfn = page_to_pfn(page);
+	unsigned long offset;
+	struct page_cgroup *base;
+
+	base = NODE_DATA(page_to_nid(page))->node_page_cgroup;
+	if (unlikely(!base))
+		return NULL;
+
+	offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
+	return base + offset;
+}
+
+static int __init alloc_node_page_cgroup(int nid)
+{
+	struct page_cgroup *base, *pc;
+	unsigned long table_size;
+	unsigned long start_pfn, nr_pages, index;
+
+	start_pfn = NODE_DATA(nid)->node_start_pfn;
+	nr_pages = NODE_DATA(nid)->node_spanned_pages;
+
+	table_size = sizeof(struct page_cgroup) * nr_pages;
+
+	base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
+			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
+	if (!base)
+		return -ENOMEM;
+	for (index = 0; index < nr_pages; index++) {
+		pc = base + index;
+		__init_page_cgroup(pc, start_pfn + index);
+	}
+	NODE_DATA(nid)->node_page_cgroup = base;
+	total_usage += table_size;
+	return 0;
+}
+
+void __init page_cgroup_init(void)
+{
+
+	int nid, fail;
+
+	for_each_online_node(nid)  {
+		fail = alloc_node_page_cgroup(nid);
+		if (fail)
+			goto fail;
+	}
+	printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
+	printk(KERN_INFO "please try cgroup_disable=memory option if you"
+	" don't want\n");
+	return;
+fail:
+	printk(KERN_CRIT "allocation of page_cgroup was failed.\n");
+	printk(KERN_CRIT "please try cgroup_disable=memory boot option\n");
+	panic("Out of memory");
+}
+
+#else /* CONFIG_FLAT_NODE_MEM_MAP */
+
+struct page_cgroup *lookup_page_cgroup(struct page *page)
+{
+	unsigned long pfn = page_to_pfn(page);
+	struct mem_section *section = __pfn_to_section(pfn);
+
+	return section->page_cgroup + pfn;
+}
+
+int __meminit init_section_page_cgroup(unsigned long pfn)
+{
+	struct mem_section *section;
+	struct page_cgroup *base, *pc;
+	unsigned long table_size;
+	int nid, index;
+
+	section = __pfn_to_section(pfn);
+
+	if (section->page_cgroup)
+		return 0;
+
+	nid = page_to_nid(pfn_to_page(pfn));
+
+	table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
+	base = kmalloc_node(table_size, GFP_KERNEL, nid);
+	if (!base)
+		base = vmalloc_node(table_size, nid);
+
+	if (!base) {
+		printk(KERN_ERR "page cgroup allocation failure\n");
+		return -ENOMEM;
+	}
+
+	for (index = 0; index < PAGES_PER_SECTION; index++) {
+		pc = base + index;
+		__init_page_cgroup(pc, pfn + index);
+	}
+
+	section = __pfn_to_section(pfn);
+	section->page_cgroup = base - pfn;
+	total_usage += table_size;
+	return 0;
+}
+#ifdef CONFIG_MEMORY_HOTPLUG
+void __free_page_cgroup(unsigned long pfn)
+{
+	struct mem_section *ms;
+	struct page_cgroup *base;
+
+	ms = __pfn_to_section(pfn);
+	if (!ms || !ms->page_cgroup)
+		return;
+	base = ms->page_cgroup + pfn;
+	ms->page_cgroup = NULL;
+	if (is_vmalloc_addr(base))
+		vfree(base);
+	else
+		kfree(base);
+}
+
+int online_page_cgroup(unsigned long start_pfn,
+			unsigned long nr_pages,
+			int nid)
+{
+	unsigned long start, end, pfn;
+	int fail = 0;
+
+	start = start_pfn & (PAGES_PER_SECTION - 1);
+	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
+
+	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
+		if (!pfn_present(pfn))
+			continue;
+		fail = init_section_page_cgroup(pfn);
+	}
+	if (!fail)
+		return 0;
+
+	/* rollback */
+	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
+		__free_page_cgroup(pfn);
+
+	return -ENOMEM;
+}
+
+int offline_page_cgroup(unsigned long start_pfn,
+		unsigned long nr_pages, int nid)
+{
+	unsigned long start, end, pfn;
+
+	start = start_pfn & (PAGES_PER_SECTION - 1);
+	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
+
+	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
+		__free_page_cgroup(pfn);
+	return 0;
+
+}
+
+static int page_cgroup_callback(struct notifier_block *self,
+			       unsigned long action, void *arg)
+{
+	struct memory_notify *mn = arg;
+	int ret = 0;
+	switch (action) {
+	case MEM_GOING_ONLINE:
+		ret = online_page_cgroup(mn->start_pfn,
+				   mn->nr_pages, mn->status_change_nid);
+		break;
+	case MEM_CANCEL_ONLINE:
+	case MEM_OFFLINE:
+		offline_page_cgroup(mn->start_pfn,
+				mn->nr_pages, mn->status_change_nid);
+		break;
+	case MEM_GOING_OFFLINE:
+		break;
+	case MEM_ONLINE:
+	case MEM_CANCEL_OFFLINE:
+		break;
+	}
+	ret = notifier_from_errno(ret);
+	return ret;
+}
+
+#endif
+
+void __init page_cgroup_init(void)
+{
+	unsigned long pfn;
+	int fail = 0;
+
+	for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {
+		if (!pfn_present(pfn))
+			continue;
+		fail = init_section_page_cgroup(pfn);
+	}
+	if (fail) {
+		printk(KERN_CRIT "try cgroup_disable=memory boot option\n");
+		panic("Out of memory");
+	} else {
+		hotplug_memory_notifier(page_cgroup_callback, 0);
+	}
+	printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
+	printk(KERN_INFO "please try cgroup_disable=memory option if you don't"
+	" want\n");
+}
+
+void __init pgdat_page_cgroup_init(struct pglist_data *pgdat)
+{
+	return;
+}
+
+#endif