hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5XQS4
CVE: NA

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In function get_process_sp_res(), spg_node can be freed by other
process, the access to spg_node->spg can cause kernel panic. Add
a pair of read lock to fix this problem.
Fix the same problem in proc_sp_group_state().

Fixes: 3d37f8717287 ("[Huawei] mm: sharepool: use built-in-statistics")
Signed-off-by: NZhang Zekun <zhangzekun11@huawei.com>