On Tue, 7 Jun 2011 10:09:00 +0100
Mel Gorman [off-list ref] wrote:
 

I should have said "nodes" even though the end result is the same. The
problem at the moment is cgroup initialisation is checking PFNs outside
node boundaries. It should be ensuring that the start and end PFNs it
uses are within boundaries.

Maybe you like this kind of fix. Yes, this can fix the problem on bugzilla.
My concern is this will not work for ARM. 

This patch (and all other patch) works on my test host.
==
make sparsemem's page_cgroup_init to be node aware.

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.

Signed-off-by: KAMEZAWA Hiroyuki <redacted>
---
 mm/page_cgroup.c |   26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

Index: linux-3.0-rc1/mm/page_cgroup.c
===================================================================

--- linux-3.0-rc1.orig/mm/page_cgroup.c
+++ linux-3.0-rc1/mm/page_cgroup.c

@@ -285,14 +285,32 @@ void __init page_cgroup_init(void)
 {
 	unsigned long pfn;
 	int fail = 0;
+	int node;
 
 	if (mem_cgroup_disabled())
 		return;
 
-	for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {
-		if (!pfn_present(pfn))
-			continue;
-		fail = init_section_page_cgroup(pfn);
+	for_each_node_state(node, N_HIGH_MEMORY) {
+		unsigned long start_pfn, end_pfn;
+
+		start_pfn = NODE_DATA(node)->node_start_pfn;
+		end_pfn = start_pfn + NODE_DATA(node)->node_spanned_pages;
+		/*
+		 * This calculation makes sure that this nid detection for
+		 * section can work even if node->start_pfn is not aligned to
+		 * section. For sections on not-node-boundary, we see head
+		 * page of sections.
+		 */
+		for (pfn = start_pfn;
+		     !fail & (pfn < end_pfn);
+		     pfn = ALIGN(pfn + PAGES_PER_SECTION, PAGES_PER_SECTION)) {
+			if (!pfn_present(pfn))
+				continue;
+			/* Nodes can be overlapped */
+			if (pfn_to_nid(pfn) != node)
+				continue;
+			fail = init_section_page_cgroup(pfn);
+		}
 	}
 	if (fail) {
 		printk(KERN_CRIT "try 'cgroup_disable=memory' boot option\n");

--

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