memcg: memory hotplug fix for notifier callback (dc19f9db) · Commits · 戴 / test

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>

mm/page_cgroup.c

+29 −14

Original line number	Diff line number	Diff line
		@@ -107,20 +107,30 @@ int __init_refok init_section_page_cgroup(unsigned long pfn)

		section = __pfn_to_section(pfn);

		if (section->page_cgroup)
		return 0;

		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,
		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) {
		printk(KERN_ERR "page cgroup allocation failure\n");
		@@ -208,18 +218,23 @@ static int __meminit page_cgroup_callback(struct notifier_block *self,
		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;
		}

		if (ret)
		ret = notifier_from_errno(ret);
		else
		ret = NOTIFY_OK;

		return ret;
		}

mm/slub.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -2931,8 +2931,10 @@ static int slab_memory_callback(struct notifier_block *self,
		case MEM_CANCEL_OFFLINE:
		break;
		}

		if (ret)
		ret = notifier_from_errno(ret);
		else
		ret = NOTIFY_OK;
		return ret;
		}

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