diff options
| author | Sean Christopherson <seanjc@google.com> | 2023-10-27 11:21:56 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-11-13 05:31:38 -0500 |
| commit | 0003e2a414687fff6a75250d381e4abf345d663f (patch) | |
| tree | 7eca3e93819013585f28865630a850a57cc03a91 /include/linux/pagemap.h | |
| parent | 5a475554db1e476a14216e742ea2bdb77362d5d5 (diff) | |
mm: Add AS_UNMOVABLE to mark mapping as completely unmovable
Add an "unmovable" flag for mappings that cannot be migrated under any
circumstance. KVM will use the flag for its upcoming GUEST_MEMFD support,
which will not support compaction/migration, at least not in the
foreseeable future.
Test AS_UNMOVABLE under folio lock as already done for the async
compaction/dirty folio case, as the mapping can be removed by truncation
while compaction is running. To avoid having to lock every folio with a
mapping, assume/require that unmovable mappings are also unevictable, and
have mapping_set_unmovable() also set AS_UNEVICTABLE.
Cc: Matthew Wilcox <willy@infradead.org>
Co-developed-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20231027182217.3615211-15-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include/linux/pagemap.h')
| -rw-r--r-- | include/linux/pagemap.h | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 351c3b7f93a1..82c9bf506b79 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -203,7 +203,8 @@ enum mapping_flags { /* writeback related tags are not used */ AS_NO_WRITEBACK_TAGS = 5, AS_LARGE_FOLIO_SUPPORT = 6, - AS_RELEASE_ALWAYS, /* Call ->release_folio(), even if no private data */ + AS_RELEASE_ALWAYS = 7, /* Call ->release_folio(), even if no private data */ + AS_UNMOVABLE = 8, /* The mapping cannot be moved, ever */ }; /** @@ -289,6 +290,22 @@ static inline void mapping_clear_release_always(struct address_space *mapping) clear_bit(AS_RELEASE_ALWAYS, &mapping->flags); } +static inline void mapping_set_unmovable(struct address_space *mapping) +{ + /* + * It's expected unmovable mappings are also unevictable. Compaction + * migrate scanner (isolate_migratepages_block()) relies on this to + * reduce page locking. + */ + set_bit(AS_UNEVICTABLE, &mapping->flags); + 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; |