3.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Li Zefan <[email protected]>

commit 3ac1707a13a3da9cfc8f242a15b2fae6df2c5f88 upstream.

The 3rd parameter of flex_array_prealloc() is the number of elements,
not the index of the last element.

The effect of the bug is, when opening cgroup.procs, a flex array will
be allocated and all elements of the array is allocated with
GFP_KERNEL flag, but the last one is GFP_ATOMIC, and if we fail to
allocate memory for it, it'll trigger a BUG_ON().

Signed-off-by: Li Zefan <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 kernel/cgroup.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2065,7 +2065,7 @@ static int cgroup_attach_proc(struct cgr
        if (!group)
                return -ENOMEM;
        /* pre-allocate to guarantee space while iterating in rcu read-side. */
-       retval = flex_array_prealloc(group, 0, group_size - 1, GFP_KERNEL);
+       retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL);
        if (retval)
                goto out_free_group_list;
 


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