memcg: add page type to memory.reclaim interface

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I7CGGT


CVE: NA

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Add anon/file to memory.reclaim interface to limit only reclaim one type
pages. The lru algorithm can reclaim cold pages and balance between file
and anon. But it didn't consider the speed of backend device. For example,
if there is zram device, reclaim anon pages might has less impact on
performance. So extend memory.reclaim interface to reclaim one type pages.
Usage:
	"echo <size> type=anon > memory.reclaim"
	"echo <size> type=file > memory.reclaim"

Also compatible with the previous format.

Signed-off-by: Liu Shixin <liushixin2@huawei.com>