memcg: memory hotplug fix for notifier callback
Fixes for memcg/memory hotplug.
While memory hotplug allocate/free memmap, page_cgroup doesn't free
page_cgroup at OFFLINE when page_cgroup is allocated via bootomem.
(Because freeing bootmem requires special care.)
Then, if page_cgroup is allocated by bootmem and memmap is freed/allocated
by memory hotplug, page_cgroup->page == page is no longer true.
But current MEM_ONLINE handler doesn't check it and update
page_cgroup->page if it's not necessary to allocate page_cgroup. (This
was not found because memmap is not freed if SPARSEMEM_VMEMMAP is y.)
And I noticed that MEM_ONLINE can be called against "part of section".
So, freeing page_cgroup at CANCEL_ONLINE will cause trouble. (freeing
used page_cgroup) Don't rollback at CANCEL.
One more, current memory hotplug notifier is stopped by slub because it
sets NOTIFY_STOP_MASK to return vaule. So, page_cgroup's callback never
be called. (low priority than slub now.)
I think this slub's behavior is not intentional(BUG). and fixes it.
Another way to be considered about page_cgroup allocation:
- free page_cgroup at OFFLINE even if it's from bootmem
and remove specieal handler. But it requires more changes.
Addresses http://bugzilla.kernel.org/show_bug.cgi?id=12041
Signed-off-by: KAMEZAWA Hiruyoki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Tested-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index 436c002..0b3cbf0 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -107,19 +107,29 @@
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;
- if (slab_is_available()) {
- base = kmalloc_node(table_size, GFP_KERNEL, nid);
- if (!base)
- base = vmalloc_node(table_size, nid);
- } else {
- base = __alloc_bootmem_node_nopanic(NODE_DATA(nid), table_size,
+ if (!section->page_cgroup) {
+ nid = page_to_nid(pfn_to_page(pfn));
+ table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
+ if (slab_is_available()) {
+ base = kmalloc_node(table_size, GFP_KERNEL, nid);
+ if (!base)
+ base = vmalloc_node(table_size, nid);
+ } else {
+ base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
+ table_size,
PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
+ }
+ } else {
+ /*
+ * We don't have to allocate page_cgroup again, but
+ * address of memmap may be changed. So, we have to initialize
+ * again.
+ */
+ base = section->page_cgroup + pfn;
+ table_size = 0;
+ /* check address of memmap is changed or not. */
+ if (base->page == pfn_to_page(pfn))
+ return 0;
}
if (!base) {
@@ -208,18 +218,23 @@
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_CANCEL_ONLINE:
case MEM_GOING_OFFLINE:
break;
case MEM_ONLINE:
case MEM_CANCEL_OFFLINE:
break;
}
- ret = notifier_from_errno(ret);
+
+ if (ret)
+ ret = notifier_from_errno(ret);
+ else
+ ret = NOTIFY_OK;
+
return ret;
}