14 Dec
2021
14 Dec
'21
5:47 p.m.
From: Keith Busch <kbusch(a)kernel.org>
commit a2a36488a61cefe3129295c6e75b3987b9d7fd13 upstream
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.
[kbusch(a)kernel.org: v11]
Link: https://lkml.kernel.org/r/20210715055145.195411-8-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20210721063926.3024591-7-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20210715055145.195411-8-ying.huang@intel.com
Cc: Keith Busch <kbusch(a)kernel.org>
Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com>
Signed-off-by: "Huang, Ying" <ying.huang(a)intel.com>
Reviewed-by: Yang Shi <shy828301(a)gmail.com>
Reviewed-by: Zi Yan <ziy(a)nvidia.com>
Cc: Michal Hocko <mhocko(a)suse.com>
Cc: Wei Xu <weixugc(a)google.com>
Cc: David Rientjes <rientjes(a)google.com>
Cc: Dan Williams <dan.j.williams(a)intel.com>
Cc: David Hildenbrand <david(a)redhat.com>
Cc: Greg Thelen <gthelen(a)google.com>
Cc: Oscar Salvador <osalvador(a)suse.de>
Cc: Yang Shi <yang.shi(a)linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org>
Signed-off-by: Baolin Wang <baolin.wang(a)linux.alibaba.com>
---
mm/vmscan.c | 34 ++++++++++++++++++++++++++++++----
1 file changed, 30 insertions(+), 4 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 682ede3..9f854ef 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -299,7 +299,7 @@ static bool writeback_throttling_sane(struct scan_control *sc)
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;
@@ -308,6 +308,31 @@ static bool can_demote(int nid, struct scan_control *sc)
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(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
@@ -319,7 +344,7 @@ unsigned long zone_reclaimable_pages(struct zone *zone)
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);
@@ -2359,6 +2384,7 @@ 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 = max(mem_cgroup_swappiness(memcg), 0);
@@ -2369,7 +2395,7 @@ static void get_scan_count(struct lruvec *lruvec, struct
scan_control *sc,
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;
}
@@ -2679,7 +2705,7 @@ static inline bool should_continue_reclaim(struct pglist_data
*pgdat,
*/
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);
if (sc->nr_reclaimed < pages_for_compaction &&
inactive_lru_pages > pages_for_compaction)
--
1.8.3.1