mm/memcontrol.c: prevent missed memory.low load tears

Looks like one of these got missed when massaging in f86b810c2610 ("mm,
memcg: prevent memory.low load/store tearing") with other linux-mm
changes.

Link: http://lkml.kernel.org/r/20200612174437.GA391453@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Reported-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Michal Hocko <mhocko@suse.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 da15b68..1962232 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6423,7 +6423,7 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
 
        if (parent == root) {
                memcg->memory.emin = READ_ONCE(memcg->memory.min);
-               memcg->memory.elow = memcg->memory.low;
+               memcg->memory.elow = READ_ONCE(memcg->memory.low);
                goto out;
        }
 
@@ -6435,7 +6435,8 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
                        atomic_long_read(&parent->memory.children_min_usage)));
 
        WRITE_ONCE(memcg->memory.elow, effective_protection(usage, parent_usage,
-                       memcg->memory.low, READ_ONCE(parent->memory.elow),
+                       READ_ONCE(memcg->memory.low),
+                       READ_ONCE(parent->memory.elow),
                        atomic_long_read(&parent->memory.children_low_usage)));
 
 out: