Commit 8d387a5f authored Oct 13, 2020 by Waiman Long Committed by Linus Torvalds Oct 13, 2020

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@redhat.com: v4]
  Link: https://lkml.kernel.org/r/20200914150928.7841-1-longman@redhat.com



Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Link: https://lkml.kernel.org/r/20200914024452.19167-3-longman@redhat.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent f9f84ec5

mm/memcontrol.c

+13 −11

Original line number	Diff line number	Diff line
		@@ -1633,17 +1633,19 @@ 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 (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)) {
		unsigned long memsw_max;
		unsigned long swap_max;
		/* 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;
		}

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