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Commit 37573e8c authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds
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memcg: fix init_page_cgroup nid with sparsemem 

Commit 21a3c964 ("memcg: allocate memory cgroup structures in local
nodes") makes page_cgroup allocation as NUMA aware.  But that caused a
problem https://bugzilla.kernel.org/show_bug.cgi?id=36192

.

The problem was getting a NID from invalid struct pages, which was not
initialized because it was out-of-node, out of [node_start_pfn,
node_end_pfn)

Now, with sparsemem, page_cgroup_init scans pfn from 0 to max_pfn.  But
this may scan a pfn which is not on any node and can access memmap which
is not initialized.

This makes page_cgroup_init() for SPARSEMEM node aware and remove a code
to get nid from page->flags.  (Then, we'll use valid NID always.)

[akpm@linux-foundation.org: try to fix up comments]
Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 89577127

mm/page_cgroup.c

+53 −18
Original line number Diff line number Diff line
@@ -162,13 +162,13 @@ static void free_page_cgroup(void *addr) 
}

#endif



static int __meminit init_section_page_cgroup(unsigned long pfn)

static int __meminit init_section_page_cgroup(unsigned long pfn, int nid)

{

	struct page_cgroup *base, *pc;

	struct mem_section *section;

	unsigned long table_size;

	unsigned long nr;

	int nid, index;

	int index;



	nr = pfn_to_section_nr(pfn);

	section = __nr_to_section(nr);
@@ -176,7 +176,6 @@ static int __meminit init_section_page_cgroup(unsigned long 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 = alloc_page_cgroup(table_size, nid);
@@ -196,7 +195,11 @@ static int __meminit init_section_page_cgroup(unsigned long pfn) 
		pc = base + index;

		init_page_cgroup(pc, nr);

	}



	/*

	 * The passed "pfn" may not be aligned to SECTION.  For the calculation

	 * we need to apply a mask.

	 */

	pfn &= PAGE_SECTION_MASK;

	section->page_cgroup = base - pfn;

	total_usage += table_size;

	return 0;
@@ -225,10 +228,20 @@ int __meminit online_page_cgroup(unsigned long start_pfn, 
	start = start_pfn & ~(PAGES_PER_SECTION - 1);

	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);



	if (nid == -1) {

		/*

		 * In this case, "nid" already exists and contains valid memory.

		 * "start_pfn" passed to us is a pfn which is an arg for

		 * online__pages(), and start_pfn should exist.

		 */

		nid = pfn_to_nid(start_pfn);

		VM_BUG_ON(!node_state(nid, N_ONLINE));

	}



	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {

		if (!pfn_present(pfn))

			continue;

		fail = init_section_page_cgroup(pfn);

		fail = init_section_page_cgroup(pfn, nid);

	}

	if (!fail)

		return 0;
@@ -284,25 +297,47 @@ static int __meminit page_cgroup_callback(struct notifier_block *self, 
void __init page_cgroup_init(void)

{

	unsigned long pfn;

	int fail = 0;

	int nid;



	if (mem_cgroup_disabled())

		return;



	for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {

		if (!pfn_present(pfn))

	for_each_node_state(nid, N_HIGH_MEMORY) {

		unsigned long start_pfn, end_pfn;



		start_pfn = node_start_pfn(nid);

		end_pfn = node_end_pfn(nid);

		/*

		 * start_pfn and end_pfn may not be aligned to SECTION and the

		 * page->flags of out of node pages are not initialized.  So we

		 * scan [start_pfn, the biggest section's pfn < end_pfn) here.

		 */

		for (pfn = start_pfn;

		     pfn < end_pfn;

                     pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {



			if (!pfn_valid(pfn))

				continue;

		fail = init_section_page_cgroup(pfn);

			/*

			 * Nodes's pfns can be overlapping.

			 * We know some arch can have a nodes layout such as

			 * -------------pfn-------------->

			 * N0 | N1 | N2 | N0 | N1 | N2|....

			 */

			if (pfn_to_nid(pfn) != nid)

				continue;

			if (init_section_page_cgroup(pfn, nid))

				goto oom;

		}

	if (fail) {

		printk(KERN_CRIT "try 'cgroup_disable=memory' boot option\n");

		panic("Out of memory");

	} else {

		hotplug_memory_notifier(page_cgroup_callback, 0);

	}

	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 memory cgroups\n");

	printk(KERN_INFO "please try 'cgroup_disable=memory' option if you "

			 "don't want memory cgroups\n");

	return;

oom:

	printk(KERN_CRIT "try 'cgroup_disable=memory' boot option\n");

	panic("Out of memory");

}



void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)