mm/sharepool: Add a task_struct parameter for sp_get_local_group()

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EORS


CVE: NA

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sp_get_local_group() could be invoked in kthread, where the current
process isn't the process we want. Add a parameter and let the caller to
avoid this problem.

Signed-off-by: Wang Wensheng <wangwensheng4@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>