[PATCH] fix spurious EBUSY on memory cgroup removal

[yamamoto-jCdQPDEk3idL9jVzuh4AOg@public.gmane.org (YAMAMOTO Takashi)]

[ resending with To: akpm.  Andrew, can you include this in -mm tree? ]

hi,

the following patch is to fix spurious EBUSY on cgroup removal.

YAMAMOTO Takashi


call mm_free_cgroup earlier.
otherwise a reference due to lazy mm switching can prevent cgroup removal.

Signed-off-by: YAMAMOTO Takashi <yamamoto-jCdQPDEk3idL9jVzuh4AOg@public.gmane.org>
Acked-by: Balbir Singh <balbir-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
---

--- linux-2.6.24-rc8-mm1/kernel/fork.c.BACKUP	2008-01-23 14:43:29.000000000 +0900
+++ linux-2.6.24-rc8-mm1/kernel/fork.c	2008-01-31 17:26:31.000000000 +0900
@@ -393,7 +393,6 @@ void __mmdrop(struct mm_struct *mm)
 {
 	BUG_ON(mm == &init_mm);
 	mm_free_pgd(mm);
-	mm_free_cgroup(mm);
 	destroy_context(mm);
 	free_mm(mm);
 }
@@ -415,6 +414,7 @@ void mmput(struct mm_struct *mm)
 			spin_unlock(&mmlist_lock);
 		}
 		put_swap_token(mm);
+		mm_free_cgroup(mm);
 		mmdrop(mm);
 	}
 }