[PATCH 2/3] mm/memcg: Simplify mem_cgroup_get_max()

Waiman Long
2020-08-20T13:04:47Z

The mem_cgroup_get_max() function 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.

Signed-off-by: Waiman Long <longman@redhat.com>
---
mm/memcontrol.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 26b7a48d3afb..d219dca5239f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1633,17 +1633,13 @@ void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
*/
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;
-
- 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);
+ if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
+ max += READ_ONCE(memcg->swap.max);
+ else
+ max = memcg->memsw.max;
}
return max;
}
--
2.18.1