[RFC PATCH 4/4] mm/damon: introduce DAMOS_PROMOTE action for promotion

Honggyu Kim
2024-01-15T04:53:09Z

From: Hyeongtak Ji <hyeongtak.ji@sk.com>

This patch introduces DAMOS_PROMOTE action for paddr mode.

It includes renaming alloc_demote_folio to alloc_migrate_folio to use it
for promotion as well.

The execution sequence of DAMOS_DEMOTE and DAMOS_PROMOTE look as
follows for comparison.

DAMOS_DEMOTE action
damo_pa_apply_scheme
-> damon_pa_reclaim
-> demote_pages
-> do_demote_folio_list
-> __demote_folio_list
-> demote_folio_list

DAMOS_PROMOTE action
damo_pa_apply_scheme
-> damon_pa_promote
-> promote_pages
-> do_promote_folio_list
-> __promote_folio_list
-> promote_folio_list

Signed-off-by: Hyeongtak Ji <hyeongtak.ji@sk.com>
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
---
include/linux/damon.h | 2 +
include/linux/migrate_mode.h | 1 +
include/linux/vm_event_item.h | 1 +
include/trace/events/migrate.h | 3 +-
mm/damon/paddr.c | 29 ++++++++
mm/damon/sysfs-schemes.c | 1 +
mm/internal.h | 1 +
mm/vmscan.c | 129 ++++++++++++++++++++++++++++++++-
mm/vmstat.c | 1 +
9 files changed, 165 insertions(+), 3 deletions(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 4c0a0fef09c5..477060bb6718 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -107,6 +107,7 @@ struct damon_target {
* @DAMOS_LRU_DEPRIO: Deprioritize the region on its LRU lists.
* @DAMOS_STAT: Do nothing but count the stat.
* @DAMOS_DEMOTE: Do demotion for the current region.
+ * @DAMOS_PROMOTE: Do promotion if possible, otherwise do nothing.
* @NR_DAMOS_ACTIONS: Total number of DAMOS actions
*
* The support of each action is up to running &struct damon_operations.
@@ -125,6 +126,7 @@ enum damos_action {
DAMOS_LRU_DEPRIO,
DAMOS_STAT, /* Do nothing but only record the stat */
DAMOS_DEMOTE,
+ DAMOS_PROMOTE,
NR_DAMOS_ACTIONS,
};

diff --git a/include/linux/migrate_mode.h b/include/linux/migrate_mode.h
index f37cc03f9369..63f75eb9abf3 100644
--- a/include/linux/migrate_mode.h
+++ b/include/linux/migrate_mode.h
@@ -29,6 +29,7 @@ enum migrate_reason {
MR_CONTIG_RANGE,
MR_LONGTERM_PIN,
MR_DEMOTION,
+ MR_PROMOTION,
MR_TYPES
};

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 8abfa1240040..63cf920afeaa 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -44,6 +44,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
PGDEMOTE_KSWAPD,
PGDEMOTE_DIRECT,
PGDEMOTE_KHUGEPAGED,
+ PGPROMOTE,
PGSCAN_KSWAPD,
PGSCAN_DIRECT,
PGSCAN_KHUGEPAGED,
diff --git a/include/trace/events/migrate.h b/include/trace/events/migrate.h
index 0190ef725b43..f0dd569c1e62 100644
--- a/include/trace/events/migrate.h
+++ b/include/trace/events/migrate.h
@@ -22,7 +22,8 @@
EM( MR_NUMA_MISPLACED, "numa_misplaced") \
EM( MR_CONTIG_RANGE, "contig_range") \
EM( MR_LONGTERM_PIN, "longterm_pin") \
- EMe(MR_DEMOTION, "demotion")
+ EM( MR_DEMOTION, "demotion") \
+ EMe(MR_PROMOTION, "promotion")

/*
* First define the enums in the above macros to be exported to userspace
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index d3e3f077cd00..360ce69d5898 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -257,6 +257,32 @@ static unsigned long damon_pa_reclaim(struct damon_region *r, struct damos *s, b
return applied * PAGE_SIZE;
}

+static unsigned long damon_pa_promote(struct damon_region *r, struct damos *s)
+{
+ unsigned long addr, applied;
+ LIST_HEAD(folio_list);
+
+ for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) {
+ struct folio *folio = damon_get_folio(PHYS_PFN(addr));
+
+ if (!folio)
+ continue;
+
+ if (damos_pa_filter_out(s, folio))
+ goto put_folio;
+
+ if (!folio_isolate_lru(folio))
+ goto put_folio;
+
+ list_add(&folio->lru, &folio_list);
+put_folio:
+ folio_put(folio);
+ }
+ applied = promote_pages(&folio_list);
+ cond_resched();
+ return applied * PAGE_SIZE;
+}
+
static inline unsigned long damon_pa_mark_accessed_or_deactivate(
struct damon_region *r, struct damos *s, bool mark_accessed)
{
@@ -309,6 +335,8 @@ static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
break;
case DAMOS_DEMOTE:
return damon_pa_reclaim(r, scheme, true);
+ case DAMOS_PROMOTE:
+ return damon_pa_promote(r, scheme);
default:
/* DAMOS actions that not yet supported by 'paddr'. */
break;
@@ -326,6 +354,7 @@ static int damon_pa_scheme_score(struct damon_ctx *context,
case DAMOS_DEMOTE:
return damon_cold_score(context, r, scheme);
case DAMOS_LRU_PRIO:
+ case DAMOS_PROMOTE:
return damon_hot_score(context, r, scheme);
default:
break;
diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index ac7cd3f17b12..1b84d0af7e1f 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1188,6 +1188,7 @@ static const char * const damon_sysfs_damos_action_strs[] = {
"lru_deprio",
"stat",
"demote",
+ "promote",
};

static struct damon_sysfs_scheme *damon_sysfs_scheme_alloc(
diff --git a/mm/internal.h b/mm/internal.h
index 2380397ec2f3..f159455e63d4 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -870,6 +870,7 @@ unsigned long reclaim_pages(struct list_head *folio_list);
unsigned int reclaim_clean_pages_from_list(struct zone *zone,
struct list_head *folio_list);
unsigned long demote_pages(struct list_head *folio_list);
+unsigned long promote_pages(struct list_head *folio_list);
/* The ALLOC_WMARK bits are used as an index to zone->watermark */
#define ALLOC_WMARK_MIN WMARK_MIN
#define ALLOC_WMARK_LOW WMARK_LOW
diff --git a/mm/vmscan.c b/mm/vmscan.c
index eaa3dd6b7562..f03be320f9ad 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -910,7 +910,7 @@ static void folio_check_dirty_writeback(struct folio *folio,
mapping->a_ops->is_dirty_writeback(folio, dirty, writeback);
}

-static struct folio *alloc_demote_folio(struct folio *src,
+static struct folio *alloc_migrate_folio(struct folio *src,
unsigned long private)
{
struct folio *dst;
@@ -973,7 +973,7 @@ static unsigned int demote_folio_list(struct list_head *demote_folios,
node_get_allowed_targets(pgdat, &allowed_mask);

/* Demotion ignores all cpuset and mempolicy settings */
- migrate_pages(demote_folios, alloc_demote_folio, NULL,
+ migrate_pages(demote_folios, alloc_migrate_folio, NULL,
(unsigned long)&mtc, MIGRATE_ASYNC, MR_DEMOTION,
&nr_succeeded);

@@ -982,6 +982,48 @@ static unsigned int demote_folio_list(struct list_head *demote_folios,
return nr_succeeded;
}

+/*
+ * Take folios on @promote_folios and attempt to promote them to another node.
+ * Folios which are not promoted are left on @promote_folios.
+ */
+static unsigned int promote_folio_list(struct list_head *promote_folios,
+ struct pglist_data *pgdat)
+{
+ int target_nid = next_promotion_node(pgdat->node_id);
+ unsigned int nr_succeeded;
+ nodemask_t allowed_mask = NODE_MASK_NONE;
+
+ struct migration_target_control mtc = {
+ /*
+ * Allocate from 'node', or fail quickly and quietly.
+ * When this happens, 'page' will likely be stayed
+ * instead of migrated.
+ */
+ .gfp_mask = (GFP_HIGHUSER_MOVABLE & ~__GFP_RECLAIM) | __GFP_NOWARN |
+ __GFP_NOMEMALLOC | GFP_NOWAIT,
+ .nid = target_nid,
+ .nmask = &allowed_mask
+ };
+
+ if (pgdat->node_id == target_nid)
+ return 0;
+
+ if (list_empty(promote_folios))
+ return 0;
+
+ if (target_nid == NUMA_NO_NODE)
+ return 0;
+
+ /* Promotion ignores all cpuset and mempolicy settings */
+ migrate_pages(promote_folios, alloc_migrate_folio, NULL,
+ (unsigned long)&mtc, MIGRATE_ASYNC, MR_PROMOTION,
+ &nr_succeeded);
+
+ __count_vm_events(PGPROMOTE, nr_succeeded);
+
+ return nr_succeeded;
+}
+
static bool may_enter_fs(struct folio *folio, gfp_t gfp_mask)
{
if (gfp_mask & __GFP_FS)
@@ -1058,6 +1100,65 @@ static unsigned int __demote_folio_list(struct list_head *folio_list,
return nr_demoted;
}

+/*
+ * __promote_folio_list() returns the number of promoted pages
+ */
+static unsigned int __promote_folio_list(struct list_head *folio_list,
+ struct pglist_data *pgdat, struct scan_control *sc)
+{
+ LIST_HEAD(ret_folios);
+ LIST_HEAD(promote_folios);
+ unsigned int nr_promoted = 0;
+
+ cond_resched();
+
+ while (!list_empty(folio_list)) {
+ struct folio *folio;
+ enum folio_references references;
+
+ cond_resched();
+
+ folio = lru_to_folio(folio_list);
+ list_del(&folio->lru);
+
+ if (!folio_trylock(folio))
+ goto keep;
+
+ VM_BUG_ON_FOLIO(folio_test_active(folio), folio);
+
+ references = folio_check_references(folio, sc);
+ if (references == FOLIOREF_KEEP ||
+ references == FOLIOREF_RECLAIM ||
+ references == FOLIOREF_RECLAIM_CLEAN)
+ goto keep_locked;
+
+ /* Relocate its contents to another node. */
+ list_add(&folio->lru, &promote_folios);
+ folio_unlock(folio);
+ continue;
+keep_locked:
+ folio_unlock(folio);
+keep:
+ list_add(&folio->lru, &ret_folios);
+ VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
+ }
+ /* 'folio_list' is always empty here */
+
+ /* Migrate folios selected for promotion */
+ nr_promoted += promote_folio_list(&promote_folios, pgdat);
+ /* Folios that could not be promoted are still in @promote_folios */
+ if (!list_empty(&promote_folios)) {
+ /* Folios which weren't promoted go back on @folio_list */
+ list_splice_init(&promote_folios, folio_list);
+ }
+
+ try_to_unmap_flush();
+
+ list_splice(&ret_folios, folio_list);
+
+ return nr_promoted;
+}
+
/*
* shrink_folio_list() returns the number of reclaimed pages
*/
@@ -2186,6 +2287,25 @@ static unsigned int do_demote_folio_list(struct list_head *folio_list,
return nr_demoted;
}

+static unsigned int do_promote_folio_list(struct list_head *folio_list,
+ struct pglist_data *pgdat)
+{
+ unsigned int nr_promoted;
+ struct folio *folio;
+ struct scan_control sc = {
+ .gfp_mask = GFP_KERNEL,
+ };
+
+ nr_promoted = __promote_folio_list(folio_list, pgdat, &sc);
+ while (!list_empty(folio_list)) {
+ folio = lru_to_folio(folio_list);
+ list_del(&folio->lru);
+ folio_putback_lru(folio);
+ }
+
+ return nr_promoted;
+}
+
static unsigned long reclaim_or_migrate_folios(struct list_head *folio_list,
unsigned int (*handler)(struct list_head *, struct pglist_data *))
{
@@ -2230,6 +2350,11 @@ unsigned long demote_pages(struct list_head *folio_list)
return reclaim_or_migrate_folios(folio_list, do_demote_folio_list);
}

+unsigned long promote_pages(struct list_head *folio_list)
+{
+ return reclaim_or_migrate_folios(folio_list, do_promote_folio_list);
+}
+
static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
struct lruvec *lruvec, struct scan_control *sc)
{
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 359460deb377..c703abdb8137 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1282,6 +1282,7 @@ const char * const vmstat_text[] = {
"pgdemote_kswapd",
"pgdemote_direct",
"pgdemote_khugepaged",
+ "pgpromote",
"pgscan_kswapd",
"pgscan_direct",
"pgscan_khugepaged",
--
2.34.1