Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
include/linux/pagemap.h | 11 +++++++++++
mm/compaction.c | 4 ++++
mm/migrate.c | 2 ++
3 files changed, 17 insertions(+)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 716953ee1ebd..931d2f1da7d5 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -203,6 +203,7 @@ enum mapping_flags {
/* writeback related tags are not used */
AS_NO_WRITEBACK_TAGS = 5,
AS_LARGE_FOLIO_SUPPORT = 6,
+ AS_UNMOVABLE = 7, /* The mapping cannot be moved, ever */
};
/**
@@ -273,6 +274,16 @@ static inline int mapping_use_writeback_tags(struct address_space *mapping)
return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
}
+static inline void mapping_set_unmovable(struct address_space *mapping)
+{
+ set_bit(AS_UNMOVABLE, &mapping->flags);
+}
+
+static inline bool mapping_unmovable(struct address_space *mapping)
+{
+ return test_bit(AS_UNMOVABLE, &mapping->flags);
+}
+
static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
{
return mapping->gfp_mask;
diff --git a/mm/compaction.c b/mm/compaction.c
index dbc9f86b1934..a3d2b132df52 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1047,6 +1047,10 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
if (!mapping && (folio_ref_count(folio) - 1) > folio_mapcount(folio))
goto isolate_fail_put;
+ /* The mapping truly isn't movable. */
+ if (mapping && mapping_unmovable(mapping))
+ goto isolate_fail_put;
+
/*
* Only allow to migrate anonymous pages in GFP_NOFS context
* because those do not depend on fs locks.
diff --git a/mm/migrate.c b/mm/migrate.c
index 24baad2571e3..c00a4ca86698 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -954,6 +954,8 @@ static int move_to_new_folio(struct folio *dst, struct folio *src,
if (!mapping)
rc = migrate_folio(mapping, dst, src, mode);
+ else if (mapping_unmovable(mapping))
+ rc = -EOPNOTSUPP;
else if (mapping->a_ops->migrate_folio)
/*
* Most folios have a mapping and most filesystems
--
2.41.0.255.g8b1d071c50-goog
