memcg: fix wrong check of noswap with softlimit

Hierarchical reclaim doesn't swap out if memsw and resource limits are
thye same (memsw_is_minimum == true) because we would hit mem+swap limit
anyway (during hard limit reclaim).

If it comes to the soft limit we shouldn't consider memsw_is_minimum at
all because it doesn't make much sense.  Either the soft limit is bellow
the hard limit and then we cannot hit mem+swap limit or the direct reclaim
takes a precedence.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 02a7947608ad151879daca76c1c0e5623cf516d2..0b1a32cbd74dbdd4f652e0c0f5b401c840602a28 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1663,7 +1663,7 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
        excess = res_counter_soft_limit_excess(&root_mem->res) >> PAGE_SHIFT;
 
        /* If memsw_is_minimum==1, swap-out is of-no-use. */
-       if (root_mem->memsw_is_minimum)
+       if (!check_soft && root_mem->memsw_is_minimum)
                noswap = true;
 
        while (1) {