memcgroup: fix spurious EBUSY on memory cgroup removal

Call mm_free_cgroup earlier.  Otherwise a reference due to lazy mm switching
can prevent cgroup removal.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/fork.c b/kernel/fork.c
index dd249c37b3a392af26a79142d0238447fee04df2..9c042f901570e1b789d40fdbda111739c733cdb4 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -394,7 +394,6 @@ 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);
 }
@@ -416,6 +415,7 @@ void mmput(struct mm_struct *mm)
                        spin_unlock(&mmlist_lock);
                }
                put_swap_token(mm);
+               mm_free_cgroup(mm);
                mmdrop(mm);
        }
 }