mm: memcontrol: switch soft limit default back to infinity

Commit 3e32cb2e0a12 ("mm: memcontrol: lockless page counters")
accidentally switched the soft limit default from infinity to zero,
which turns all memcgs with even a single page into soft limit excessors
and engages soft limit reclaim on all of them during global memory
pressure.  This makes global reclaim generally more aggressive, but also
inverts the meaning of existing soft limit configurations where unset
soft limits are usually more generous than set ones.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vladimir Davydov <vdavydov@parallels.com>
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 ef91e856c7e456a0674e7b76e15cbd771a6c9acb..b7104a55ae645845390f2f24da89c439c01217a4 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4679,6 +4679,7 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
        if (parent_css == NULL) {
                root_mem_cgroup = memcg;
                page_counter_init(&memcg->memory, NULL);
+               memcg->soft_limit = PAGE_COUNTER_MAX;
                page_counter_init(&memcg->memsw, NULL);
                page_counter_init(&memcg->kmem, NULL);
        }
@@ -4724,6 +4725,7 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
 
        if (parent->use_hierarchy) {
                page_counter_init(&memcg->memory, &parent->memory);
+               memcg->soft_limit = PAGE_COUNTER_MAX;
                page_counter_init(&memcg->memsw, &parent->memsw);
                page_counter_init(&memcg->kmem, &parent->kmem);
 
@@ -4733,6 +4735,7 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
                 */
        } else {
                page_counter_init(&memcg->memory, NULL);
+               memcg->soft_limit = PAGE_COUNTER_MAX;
                page_counter_init(&memcg->memsw, NULL);
                page_counter_init(&memcg->kmem, NULL);
                /*
@@ -4807,7 +4810,7 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
        mem_cgroup_resize_limit(memcg, PAGE_COUNTER_MAX);
        mem_cgroup_resize_memsw_limit(memcg, PAGE_COUNTER_MAX);
        memcg_update_kmem_limit(memcg, PAGE_COUNTER_MAX);
-       memcg->soft_limit = 0;
+       memcg->soft_limit = PAGE_COUNTER_MAX;
 }
 
 #ifdef CONFIG_MMU