From: Waiman Long <longman@xxxxxxxxxx> Subject: mm/memcg: simplify mem_cgroup_get_max() mem_cgroup_get_max() used to get memory+swap max from both the v1 memsw and v2 memory+swap page counters & return the maximum of these 2 values. This is redundant and it is more efficient to just get either the v1 or the v2 values depending on which one is currently in use. [longman@xxxxxxxxxx: v4] Link: https://lkml.kernel.org/r/20200914150928.7841-1-longman@xxxxxxxxxx Link: https://lkml.kernel.org/r/20200914024452.19167-3-longman@xxxxxxxxxx Signed-off-by: Waiman Long <longman@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx> Cc: Chris Down <chris@xxxxxxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Roman Gushchin <guro@xxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Cc: Yafang Shao <laoar.shao@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memcontrol.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) --- a/mm/memcontrol.c~mm-memcg-simplify-mem_cgroup_get_max +++ a/mm/memcontrol.c @@ -1633,17 +1633,19 @@ void mem_cgroup_print_oom_meminfo(struct */ unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg) { - unsigned long max; + unsigned long max = READ_ONCE(memcg->memory.max); - max = READ_ONCE(memcg->memory.max); - if (mem_cgroup_swappiness(memcg)) { - unsigned long memsw_max; - unsigned long swap_max; + if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) { + if (mem_cgroup_swappiness(memcg)) + max += min(READ_ONCE(memcg->swap.max), + (unsigned long)total_swap_pages); + } else { /* v1 */ + if (mem_cgroup_swappiness(memcg)) { + /* Calculate swap excess capacity from memsw limit */ + unsigned long swap = READ_ONCE(memcg->memsw.max) - max; - memsw_max = memcg->memsw.max; - swap_max = READ_ONCE(memcg->swap.max); - swap_max = min(swap_max, (unsigned long)total_swap_pages); - max = min(max + swap_max, memsw_max); + max += min(swap, (unsigned long)total_swap_pages); + } } return max; } _
