mm, memcg: partially revert "mm/memcontrol.c: keep local VM counters in sync...

mm, memcg: partially revert "mm/memcontrol.c: keep local VM counters in sync with the hierarchical ones"

mainline inclusion
from mainline-v5.3-rc7
commit b4c46484
category: bugfix
bugzilla: 51815, https://gitee.com/openeuler/kernel/issues/I3IJ9I
CVE: NA

-------------------------------------------------

Commit 766a4c19 ("mm/memcontrol.c: keep local VM counters in sync
with the hierarchical ones") effectively decreased the precision of
per-memcg vmstats_local and per-memcg-per-node lruvec percpu counters.

That's good for displaying in memory.stat, but brings a serious
regression into the reclaim process.

One issue I've discovered and debugged is the following:
lruvec_lru_size() can return 0 instead of the actual number of pages in
the lru list, preventing the kernel to reclaim last remaining pages.
Result is yet another dying memory cgroups flooding.  The opposite is
also happening: scanning an empty lru list is the waste of cpu time.

Also, inactive_list_is_low() can return incorrect values, preventing the
active lru from being scanned and freed.  It can fail both because the
size of active and inactive lists are inaccurate, and because the number
of workingset refaults isn't precise.  In other words, the result is
pretty random.

I'm not sure, if using the approximate number of slab pages in
count_shadow_number() is acceptable, but issues described above are
enough to partially revert the patch.

Let's keep per-memcg vmstat_local batched (they are only used for
displaying stats to the userspace), but keep lruvec stats precise.  This
change fixes the dead memcg flooding on my setup.

Link: http://lkml.kernel.org/r/20190817004726.2530670-1-guro@fb.com


Fixes: 766a4c19 ("mm/memcontrol.c: keep local VM counters in sync with the hierarchical ones")
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
(cherry-pick commit from 81b6bde6ce186b25297ffc0138f9bc4523f3497c)
Signed-off-by: Lu Jialin <lujialin4@huawei.com>
Reviewed-by: Jing Xiangfeng <jingxiangfeng@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>