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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2008-12-01 13:13:48 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2008-12-01 19:55:24 -0800
commitdc19f9db38295f811d9041bd89b113beccbd763a (patch)
tree6f1ce3a71df84981b4b5b70fd03f0d1fe20b196e /mm/slub.c
parentb29acbdcf877009af3f1fc0750bcac314c51e055 (diff)
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>
Diffstat (limited to 'mm/slub.c')
-rw-r--r--mm/slub.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/slub.c b/mm/slub.c
index 7ad489af956..749588a50a5 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2931,8 +2931,10 @@ static int slab_memory_callback(struct notifier_block *self,
case MEM_CANCEL_OFFLINE:
break;
}
-
- ret = notifier_from_errno(ret);
+ if (ret)
+ ret = notifier_from_errno(ret);
+ else
+ ret = NOTIFY_OK;
return ret;
}