The patch titled
Subject: mm/vmscan: Consider anonymous pages without swap
has been added to the -mm tree. Its filename is
mm-vmscan-consider-anonymous-pages-without-swap.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-vmscan-consider-anonymous-pages-without-swap.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-vmscan-consider-anonymous-pages-without-swap.patch
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------------------------------------------------------
From: Keith Busch <kbusch@xxxxxxxxxx>
Subject: mm/vmscan: Consider anonymous pages without swap
Reclaim anonymous pages if a migration path is available now that demotion
provides a non-swap recourse for reclaiming anon pages.
Note that this check is subtly different from the can_age_anon_pages()
checks. This mechanism checks whether a specific page in a specific
context can actually be reclaimed, given current swap space and cgroup
limits.
can_age_anon_pages() is a much simpler and more preliminary check which
just says whether there is a possibility of future reclaim.
Link: https://lkml.kernel.org/r/20210715055145.195411-8-ying.huang@xxxxxxxxx
Cc: Keith Busch <kbusch@xxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Cc: Wei Xu <weixugc@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 34 ++++++++++++++++++++++++++++++----
1 file changed, 30 insertions(+), 4 deletions(-)
--- a/mm/vmscan.c~mm-vmscan-consider-anonymous-pages-without-swap
+++ a/mm/vmscan.c
@@ -521,7 +521,7 @@ static long add_nr_deferred(long nr, str
static bool can_demote(int nid, struct scan_control *sc)
{
- if (sc->no_demotion)
+ if (sc && sc->no_demotion)
return false;
if (next_demotion_node(nid) == NUMA_NO_NODE)
return false;
@@ -530,6 +530,31 @@ static bool can_demote(int nid, struct s
return false;
}
+static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg,
+ int nid,
+ struct scan_control *sc)
+{
+ if (memcg == NULL) {
+ /*
+ * For non-memcg reclaim, is there
+ * space in any swap device?
+ */
+ if (get_nr_swap_pages() > 0)
+ return true;
+ } else {
+ /* Is the memcg below its swap limit? */
+ if (mem_cgroup_get_nr_swap_pages(memcg) > 0)
+ return true;
+ }
+
+ /*
+ * The page can not be swapped.
+ *
+ * Can it be reclaimed from this node via demotion?
+ */
+ return can_demote_anon_pages(nid, sc);
+}
+
/*
* This misses isolated pages which are not accounted for to save counters.
* As the data only determines if reclaim or compaction continues, it is
@@ -541,7 +566,7 @@ unsigned long zone_reclaimable_pages(str
nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) +
zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE);
- if (get_nr_swap_pages() > 0)
+ if (can_reclaim_anon_pages(NULL, zone_to_nid(zone), NULL))
nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) +
zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON);
@@ -2545,6 +2570,7 @@ enum scan_balance {
static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
unsigned long *nr)
{
+ struct pglist_data *pgdat = lruvec_pgdat(lruvec);
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
unsigned long anon_cost, file_cost, total_cost;
int swappiness = mem_cgroup_swappiness(memcg);
@@ -2555,7 +2581,7 @@ static void get_scan_count(struct lruvec
enum lru_list lru;
/* If we have no swap space, do not bother scanning anon pages. */
- if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) {
+ if (!sc->may_swap || !can_reclaim_anon_pages(memcg, pgdat->node_id, sc)) {
scan_balance = SCAN_FILE;
goto out;
}
@@ -2925,7 +2951,7 @@ static inline bool should_continue_recla
*/
pages_for_compaction = compact_gap(sc->order);
inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE);
- if (get_nr_swap_pages() > 0)
+ if (can_reclaim_anon_pages(NULL, pgdat->node_id, sc))
inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON);
return inactive_lru_pages > pages_for_compaction;
_
Patches currently in -mm which might be from kbusch@xxxxxxxxxx are
mm-vmscan-consider-anonymous-pages-without-swap.patch
mm-vmscan-consider-anonymous-pages-without-swap-v11.patch
