mm: export collect_procs()

ascend inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I53VVE


CVE: NA

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Collect the processes who have the page mapped via collect_procs().

@page if the page is a part of the hugepages/compound-page, we must
using compound_head() to find it's head page to prevent the kernel panic,
and make the page be locked.

@to_kill the function will return a linked list, when we have used
this list, we must kfree the list.

@force_early if we want to find all process, we must make it be true, if
it's false, the function will only return the process who have PF_MCE_PROCESS
or PF_MCE_EARLY mark.

limits: if force_early is true, sysctl_memory_failure_early_kill is useless.
If it's false, no process have PF_MCE_PROCESS and PF_MCE_EARLY flag, and
the sysctl_memory_failure_early_kill is enabled, function will return all tasks
whether the task have the PF_MCE_PROCESS and PF_MCE_EARLY flag.

Signed-off-by: Zhang Jian <zhangjian210@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Reviewed-by: Kefeng <Wang&lt;wangkefeng.wang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>