[RESEND PATCH] mm: bail out from partial cgroup_reclaim inside shrink_lruvec

["zhaoyang.huang" <zhaoyang.huang@unisoc.com>]

From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>

Nowadays, ANDROID system replaces madivse with memory.reclaim to implement
user space memory management which desires to reclaim a certain amount of
memcg's memory. However, oversized reclaiming and high latency are observed
as there is no limitation over nr_reclaimed inside try_to_shrink_lruvec
when MGLRU enabled. Besides, this could also affect all none root_reclaim
such as reclaim_high etc.
The commit 'b82b530740b9' ("mm: vmscan: restore incremental cgroup
iteration") introduces sc->memcg_full_walk to limit the walk range of
mem_cgroup_iter. This commit would like to make single memcg's scanning
more precised by judging if nr_reclaimed reached when sc->memcg_full_walk
not set.

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
---
 mm/vmscan.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 670fe9fae5ba..03bda1094621 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4832,8 +4832,8 @@ static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)
 	int i;
 	enum zone_watermarks mark;
 
-	/* don't abort memcg reclaim to ensure fairness */
-	if (!root_reclaim(sc))
+	/* don't abort full walk memcg reclaim to ensure fairness */
+	if (!root_reclaim(sc) && sc->memcg_full_walk)
 		return false;
 
 	if (sc->nr_reclaimed >= max(sc->nr_to_reclaim, compact_gap(sc->order)))
-- 
2.25.1