[PATCH RFC 20/37] mm: compaction: Reserve metadata storage in compaction_alloc()

Alexandru Elisei
2023-08-23T13:16:24Z

If the source page being migrated has metadata associated with it, make
sure to reserve the metadata storage when choosing a suitable destination
page from the free list.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
mm/compaction.c | 9 +++++++++
mm/internal.h | 1 +
2 files changed, 10 insertions(+)

diff --git a/mm/compaction.c b/mm/compaction.c
index cc0139fa0cb0..af2ee3085623 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -570,6 +570,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
bool locked = false;
unsigned long blockpfn = *start_pfn;
unsigned int order;
+ int ret;

/* Strict mode is for isolation, speed is secondary */
if (strict)
@@ -626,6 +627,11 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,

/* Found a free page, will break it into order-0 pages */
order = buddy_order(page);
+ if (metadata_storage_enabled() && cc->reserve_metadata) {
+ ret = reserve_metadata_storage(page, order, cc->gfp_mask);
+ if (ret)
+ goto isolate_fail;
+ }
isolated = __isolate_free_page(page, order);
if (!isolated)
break;
@@ -1757,6 +1763,9 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data)
struct compact_control *cc = (struct compact_control *)data;
struct folio *dst;

+ if (metadata_storage_enabled())
+ cc->reserve_metadata = folio_has_metadata(src);
+
if (list_empty(&cc->freepages)) {
isolate_freepages(cc);

diff --git a/mm/internal.h b/mm/internal.h
index d28ac0085f61..046cc264bfbe 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -492,6 +492,7 @@ struct compact_control {
*/
bool alloc_contig; /* alloc_contig_range allocation */
bool source_has_metadata; /* source pages have associated metadata */
+ bool reserve_metadata;
};

/*
--
2.41.0