On 01/29/2013 05:57 PM, Lord Glauber Costa of Sealand wrote:
> On 01/28/2013 02:54 PM, Jeff Liu wrote:
>> Introduce swap_cgroup_init()/swap_cgroup_free() to allocate buffers when creating the first
>> non-root memcg and deallocate buffers on the last non-root memcg is gone.
>>
>> Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
>> CC: Glauber Costa <glommer@xxxxxxxxxxxxx>
>> CC: Michal Hocko <mhocko@xxxxxxx>
>> CC: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>> CC: Johannes Weiner <hannes@xxxxxxxxxxx>
>> CC: Mel Gorman <mgorman@xxxxxxx>
>> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> CC: Sha Zhengju <handai.szj@xxxxxxxxxx>
>>
>
> Looks sane.
>
> Reviewed-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
>
> Only:
>
>> #endif /* !__GENERATING_BOUNDS_H */
>> diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
>> index 189fbf5..0ebd127 100644
>> --- a/mm/page_cgroup.c
>> +++ b/mm/page_cgroup.c
>> @@ -362,14 +362,28 @@ static int swap_cgroup_prepare(int type)
>> unsigned long idx, max;
>>
>> ctrl = &swap_cgroup_ctrl[type];
>> + if (!ctrl->length) {
>> + /*
>> + * Bypass the buffer allocation if the corresponding swap
>> + * partition/file was turned off.
>> + */
>> + pr_debug("couldn't allocate swap_cgroup on a disabled swap "
>> + "partition or file, index: %d\n", type);
>> + return 0;
>> + }
>> +
>> ctrl->map = vzalloc(ctrl->length * sizeof(void *));
>> - if (!ctrl->map)
>> + if (!ctrl->map) {
>> + ctrl->length = 0;
>
> Considering moving this assignment somewhere in the exit path in the
> labels region.
Nice point. Both "ctrl->length = 0" statements in this function should be
moved down to the exit path of "nomem:" label.
Thanks,
-Jeff
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