mm/memcg: bail early from swap accounting if memcg disabled

Patch series "bail out early for memcg disable".

These 2 patches are indepenedent from per memcg lru lock, and may
encounter unexpected warning, so let's move out them from per memcg
lru locking patchset.

This patch (of 2):

We could bail out early when memcg wasn't enabled.

Link: https://lkml.kernel.org/r/1604283436-18880-1-git-send-email-alex.shi@linux.alibaba.com
Link: https://lkml.kernel.org/r/1604283436-18880-2-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.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 e3c7ca7..5c3b054 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7178,6 +7178,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
        VM_BUG_ON_PAGE(PageLRU(page), page);
        VM_BUG_ON_PAGE(page_count(page), page);
 
+       if (mem_cgroup_disabled())
+               return;
+
        if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
                return;
 
@@ -7242,6 +7245,9 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
        struct mem_cgroup *memcg;
        unsigned short oldid;
 
+       if (mem_cgroup_disabled())
+               return 0;
+
        if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
                return 0;