From: Chen Ridong <chenridong@huawei.com>
The previous patch extended shrink_one to support both lrugen and
non-lrugen reclaim. Now shrink_many and shrink_node_memcgs are almost
identical, except that shrink_many also calls should_abort_scan for lrugen
root reclaim.
This patch adds the should_abort_scan check to shrink_node_memcgs (which is
only meaningful for gen-LRU root reclaim). After this change,
shrink_node_memcgs can be used directly instead of shrink_many, allowing
shrink_many to be safely removed.
Suggested-by: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
---
mm/vmscan.c | 67 ++++++++++++-----------------------------------------
1 file changed, 15 insertions(+), 52 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 795f5ebd9341..dbf2cfbe3243 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4758,57 +4758,6 @@ static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
return nr_to_scan < 0;
}
-static void shrink_one(struct lruvec *lruvec, struct scan_control *sc);
-
-static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc)
-{
- struct mem_cgroup *target = sc->target_mem_cgroup;
- struct mem_cgroup_reclaim_cookie reclaim = {
- .pgdat = pgdat,
- };
- struct mem_cgroup_reclaim_cookie *cookie = &reclaim;
- struct mem_cgroup *memcg;
-
- if (current_is_kswapd() || sc->memcg_full_walk)
- cookie = NULL;
-
- memcg = mem_cgroup_iter(target, NULL, cookie);
- while (memcg) {
- struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
-
- cond_resched();
-
- mem_cgroup_calculate_protection(target, memcg);
-
- if (mem_cgroup_below_min(target, memcg))
- goto next;
-
- if (mem_cgroup_below_low(target, memcg)) {
- if (!sc->memcg_low_reclaim) {
- sc->memcg_low_skipped = 1;
- goto next;
- }
- memcg_memory_event(memcg, MEMCG_LOW);
- }
-
- shrink_one(lruvec, sc);
-
- if (should_abort_scan(lruvec, sc)) {
- if (cookie)
- mem_cgroup_iter_break(target, memcg);
- break;
- }
-
-next:
- if (cookie && sc->nr_reclaimed >= sc->nr_to_reclaim) {
- mem_cgroup_iter_break(target, memcg);
- break;
- }
-
- memcg = mem_cgroup_iter(target, memcg, cookie);
- }
-}
-
static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
{
struct blk_plug plug;
@@ -4829,6 +4778,9 @@ static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc
blk_finish_plug(&plug);
}
+static void shrink_one(struct lruvec *lruvec, struct scan_control *sc);
+static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc);
+
static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)
{
struct blk_plug plug;
@@ -4858,7 +4810,7 @@ static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *
if (mem_cgroup_disabled())
shrink_one(&pgdat->__lruvec, sc);
else
- shrink_many(pgdat, sc);
+ shrink_node_memcgs(pgdat, sc);
if (current_is_kswapd())
sc->nr_reclaimed += reclaimed;
@@ -5554,6 +5506,11 @@ static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *
BUILD_BUG();
}
+static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)
+{
+ return false;
+}
+
#endif /* CONFIG_LRU_GEN */
static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
@@ -5822,6 +5779,12 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
shrink_one(lruvec, sc);
+ if (should_abort_scan(lruvec, sc)) {
+ if (partial)
+ mem_cgroup_iter_break(target_memcg, memcg);
+ break;
+ }
+
/* If partial walks are allowed, bail once goal is reached */
if (partial && sc->nr_reclaimed >= sc->nr_to_reclaim) {
mem_cgroup_iter_break(target_memcg, memcg);
--
2.34.1On Tue, Dec 09, 2025 at 01:25:56AM +0000, Chen Ridong wrote:
> @@ -5822,6 +5779,12 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
>
> shrink_one(lruvec, sc);
>
> + if (should_abort_scan(lruvec, sc)) {
Can you please rename this and add the jump label check?
if (lru_gen_enabled() && lru_gen_should_abort_scan())
The majority of the checks in there already happen inside
shrink_node_memcgs() itself. Factoring those out is probably better in
another patch, but no need to burden classic LRU in the meantime.
On 2025/12/16 5:17, Johannes Weiner wrote:
> On Tue, Dec 09, 2025 at 01:25:56AM +0000, Chen Ridong wrote:
>> @@ -5822,6 +5779,12 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
>>
>> shrink_one(lruvec, sc);
>>
>> + if (should_abort_scan(lruvec, sc)) {
>
> Can you please rename this and add the jump label check?
>
> if (lru_gen_enabled() && lru_gen_should_abort_scan())
>
> The majority of the checks in there already happen inside
> shrink_node_memcgs() itself. Factoring those out is probably better in
> another patch, but no need to burden classic LRU in the meantime.
Adding should_abort_scan for the classic LRU seems reasonable, as it would allow the scan to stop
earlier when sufficient pages have been reclaimed or watermark is satisfied for global recalim.
Refer to the discussion here:
https://lore.kernel.org/lkml/20251209012557.1949239-1-chenridong@huaweicloud.com/T/#m4eea017f5a222ba676d9222f59ad8c898ac2aefe
--
Best regards,
Ridong
On 2025/12/16 5:17, Johannes Weiner wrote:
> On Tue, Dec 09, 2025 at 01:25:56AM +0000, Chen Ridong wrote:
>> @@ -5822,6 +5779,12 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
>>
>> shrink_one(lruvec, sc);
>>
>> + if (should_abort_scan(lruvec, sc)) {
>
> Can you please rename this and add the jump label check?
>
> if (lru_gen_enabled() && lru_gen_should_abort_scan())
>
> The majority of the checks in there already happen inside
> shrink_node_memcgs() itself. Factoring those out is probably better in
> another patch, but no need to burden classic LRU in the meantime.
Thank you very much.
Thank you for the suggestion. lru_gen_should_abort_scan() is indeed a better name, and including the
lru_gen_enabled() check in the condition is necessary.
I'll update the patch accordingly.
--
Best regards,
Ridong
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