Currently, drop_caches are reclaiming node-by-node, looping on each node
until reclaim could not make progress. This can however leave quite some
slab entries (such as filesystem inodes) unreclaimed if objects say on
node 1 keep objects on node 0 pinned. So move the "loop until no
progress" loop to the node-by-node iteration to retry reclaim also on
other nodes if reclaim on some nodes made progress. This fixes problem
when drop_caches was not reclaiming lots of otherwise perfectly fine to
reclaim inodes.
Reported-by: You Zhou <you.zhou@xxxxxxxxx>
Reported-and-tested-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
mm/vmscan.c | 33 ++++++++++++++++++---------------
1 file changed, 18 insertions(+), 15 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 04d8b88e5216..70d6d035b0fc 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1020,31 +1020,34 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
return freed;
}
-static void drop_slab_node(int nid)
+static unsigned long drop_slab_node(int nid)
{
- unsigned long freed;
- int shift = 0;
+ unsigned long freed = 0;
+ struct mem_cgroup *memcg = NULL;
+ memcg = mem_cgroup_iter(NULL, NULL, NULL);
do {
- struct mem_cgroup *memcg = NULL;
-
- if (fatal_signal_pending(current))
- return;
+ freed += shrink_slab(GFP_KERNEL, nid, memcg, 0);
+ } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
- freed = 0;
- memcg = mem_cgroup_iter(NULL, NULL, NULL);
- do {
- freed += shrink_slab(GFP_KERNEL, nid, memcg, 0);
- } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
- } while ((freed >> shift++) > 1);
+ return freed;
}
void drop_slab(void)
{
int nid;
+ int shift = 0;
+ unsigned long freed;
- for_each_online_node(nid)
- drop_slab_node(nid);
+ do {
+ freed = 0;
+ for_each_online_node(nid) {
+ if (fatal_signal_pending(current))
+ return;
+
+ freed += drop_slab_node(nid);
+ }
+ } while ((freed >> shift++) > 1);
}
static inline int is_page_cache_freeable(struct folio *folio)
--
2.35.3
