[RFC PATCH v11 10/29] mm: Add AS_UNMOVABLE to mark mapping as completely unmovable
From: Sean Christopherson <seanjc@google.com>
Date: 2023-07-18 23:50:36
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-fsdevel, linux-mips, linux-mm, linux-riscv, linuxppc-dev, lkml
Subsystem:
memory management, memory management - memory policy and migration, memory management - page allocator, page cache, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Vlastimil Babka, Matthew Wilcox, Linus Torvalds
Signed-off-by: Sean Christopherson <seanjc@google.com> --- 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