On Thu, 9 Jun 2011 10:04:34 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> On Wed, 8 Jun 2011 12:15:11 +0200
> Johannes Weiner <hannes@xxxxxxxxxxx> wrote:
> Thank you for review.
updated.
==
>From a4f043565ad2388f930d956958b1167761e7d6a0 Mon Sep 17 00:00:00 2001
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Date: Wed, 8 Jun 2011 17:13:37 +0900
Subject: [PATCH] [BUGFIX] Avoid getting nid from invalid struct page at page_cgroup allocation.
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.)
This is a fix for Bug 36192.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Changelog:
Jun/9
- use PAGE_SECTION_MASK
- add comments for init_section_page_cgroup
- changed return value for init_section_page_cgroup
- changed loop style.
- fixed nid handling at memory hotplug.
Jun/8
- moved ALIGN(pfn, PAGES_PER_SECTION) to nearby it's really meaningful
- use "nid" instead of node.
- use pfn_valid() instead of pfn_present().
- fixed usage of ALIGN...I misunderstood.
---
mm/page_cgroup.c | 86 ++++++++++++++++++++++++++++++++++++++---------------
1 files changed, 61 insertions(+), 25 deletions(-)
diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index 74ccff6..9ef0657 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -162,21 +162,28 @@ static void free_page_cgroup(void *addr)
}
#endif
-static int __meminit init_section_page_cgroup(unsigned long pfn)
+/** init_section_page_cgroup - initialize page_cgroup for a section.
+ * @pfn - pfn of a section should be initialized.
+ * @nid - nid where the memory should be allocated from.
+ *
+ * Allocates and initialized page_cgroup for a section. At success, this
+ * returns start_pfn of the next section. At failure, this returns 0.
+ */
+static unsigned long
+__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);
if (section->page_cgroup)
- return 0;
+ goto out;
- nid = page_to_nid(pfn_to_page(pfn));
table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
base = alloc_page_cgroup(table_size, nid);
@@ -189,17 +196,22 @@ static int __meminit init_section_page_cgroup(unsigned long pfn)
if (!base) {
printk(KERN_ERR "page cgroup allocation failure\n");
- return -ENOMEM;
+ return 0;
}
for (index = 0; index < PAGES_PER_SECTION; index++) {
pc = base + index;
init_page_cgroup(pc, nr);
}
-
+ /*
+ * Even if passed 'pfn' is not aligned to section, we need to align
+ * it to section boundary because of SPARSEMEM pfn calculation.
+ */
+ pfn = pfn & PAGE_SECTION_MASK;
section->page_cgroup = base - pfn;
total_usage += table_size;
- return 0;
+out:
+ return ALIGN(pfn + 1, PAGES_PER_SECTION);
}
#ifdef CONFIG_MEMORY_HOTPLUG
void __free_page_cgroup(unsigned long pfn)
@@ -220,19 +232,23 @@ int __meminit online_page_cgroup(unsigned long start_pfn,
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))
+ if (nid == -1)
+ nid = pfn_to_nid(start_pfn);
+
+ pfn = start_pfn;
+ while (pfn < end) {
+ if (!pfn_valid(pfn))
continue;
- fail = init_section_page_cgroup(pfn);
+ pfn = init_section_page_cgroup(pfn, nid);
+ if (!pfn)
+ goto rollback;
}
- if (!fail)
- return 0;
-
+ return 0;
+rollback:
/* rollback */
for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
__free_page_cgroup(pfn);
@@ -284,25 +300,45 @@ 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))
- 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);
+ for_each_node_state(nid, N_HIGH_MEMORY) {
+ unsigned long start_pfn, end_pfn;
+
+ start_pfn = NODE_DATA(nid)->node_start_pfn;
+ end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages;
+ /*
+ * Because we cannot trust page->flags of page out of node
+ * boundary, we skip pfn < start_pfn.
+ */
+ pfn = start_pfn;
+ while (pfn < end_pfn) {
+ /*
+ * Nodes can be overlapped
+ * We know some arch can have nodes layout as
+ * -------------pfn-------------->
+ * N0 | N1 | N2 | N0 | N1 | N2 |.....
+ */
+ if (!pfn_valid(pfn) || (pfn_to_nid(pfn) != nid)) {
+ pfn = ALIGN(pfn + 1, PAGES_PER_SECTION);
+ continue;
+ }
+ pfn = init_section_page_cgroup(pfn, nid);
+ if (!pfn)
+ goto fail;
+ }
}
+ 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");
+ return;
+fail:
+ printk(KERN_CRIT "try 'cgroup_disable=memory' boot option\n");
+ panic("Out of memory");
}
void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)
--
1.7.4.1
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