Explicitly propagate effective memory min/low values down by the tree. If there is the global memory pressure, it's not really necessary. Effective memory guarantees will be propagated automatically as we traverse memory cgroup tree in the reclaim path. But if there is no global memory pressure, effective memory protection still matters for local (memcg-scoped) memory pressure. So, we have to update effective limits in the subtree, if a user changes memory.min and memory.low values. Link: http://lkml.kernel.org/r/20180522132528.23769-1-guro@xxxxxx Signed-off-by: Roman Gushchin <guro@xxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Cc: Greg Thelen <gthelen@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Shuah Khan <shuah@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxx> --- mm/memcontrol.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 5a3873e9d657..485df6f63d26 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5084,7 +5084,7 @@ static int memory_min_show(struct seq_file *m, void *v) static ssize_t memory_min_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { - struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); + struct mem_cgroup *iter, *memcg = mem_cgroup_from_css(of_css(of)); unsigned long min; int err; @@ -5095,6 +5095,11 @@ static ssize_t memory_min_write(struct kernfs_open_file *of, page_counter_set_min(&memcg->memory, min); + rcu_read_lock(); + for_each_mem_cgroup_tree(iter, memcg) + mem_cgroup_protected(NULL, iter); + rcu_read_unlock(); + return nbytes; } @@ -5114,7 +5119,7 @@ static int memory_low_show(struct seq_file *m, void *v) static ssize_t memory_low_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { - struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); + struct mem_cgroup *iter, *memcg = mem_cgroup_from_css(of_css(of)); unsigned long low; int err; @@ -5125,6 +5130,11 @@ static ssize_t memory_low_write(struct kernfs_open_file *of, page_counter_set_low(&memcg->memory, low); + rcu_read_lock(); + for_each_mem_cgroup_tree(iter, memcg) + mem_cgroup_protected(NULL, iter); + rcu_read_unlock(); + return nbytes; } -- 2.14.4
