mm: memcontrol: set the correct memcg swappiness restriction

Since commit c843966c ("mm: allow swappiness that prefers reclaiming
anon over the file workingset") has expended the swappiness value to make
swap to be preferred in some systems.  We should also change the memcg
swappiness restriction to allow memcg swap-preferred.

Link: https://lkml.kernel.org/r/d77469b90c45c49953ccbc51e54a1d465bc18f70.1627626255.git.baolin.wang@linux.alibaba.com
Fixes: c843966c ("mm: allow swappiness that prefers reclaiming anon over the file workingset")
Signed-off-by: NBaolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/memcontrol.c

@@ -4062,7 +4062,7 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 
-	if (val > 100)
+	if (val > 200)
 		return -EINVAL;
 
 	if (!mem_cgroup_is_root(memcg))