mm/memcg: fix cache growth above cache.limit_in_bytes

Submitted by Andrey Ryabinin on July 30, 2020, 1:56 p.m.

Details

Message ID 20200730135619.19888-1-aryabinin@virtuozzo.com
State New
Series "mm/memcg: fix cache growth above cache.limit_in_bytes"
Headers show

Commit Message

Andrey Ryabinin July 30, 2020, 1:56 p.m.
Exceeding cache above cache.limit_in_bytes schedules high_work_func()
which tries to reclaim 32 pages. If cache generated fast enough or it allows
cgroup to steadily grow above cache.limit_in_bytes because we don't reclaim
enough. Try to reclaim exceeded amount of cache instead.

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
---
 mm/memcontrol.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

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diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3cf200f506c3..e5adb0e81cbb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3080,12 +3080,16 @@  static void reclaim_high(struct mem_cgroup *memcg,
 {
 
 	do {
+		unsigned long cache_overused;
+
 		if (page_counter_read(&memcg->memory) > memcg->high)
 			try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, 0);
 
-		if (page_counter_read(&memcg->cache) > memcg->cache.limit)
-			try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask,
-						MEM_CGROUP_RECLAIM_NOSWAP);
+		cache_overused = page_counter_read(&memcg->cache) -
+			memcg->cache.limit;
+		if (cache_overused)
+			try_to_free_mem_cgroup_pages(memcg, cache_overused,
+					gfp_mask, MEM_CGROUP_RECLAIM_NOSWAP);
 
 	} while ((memcg = parent_mem_cgroup(memcg)));
 }