mm/codetag: add pgalloc_tag_copy()

Add pgalloc_tag_copy() to transfer the codetag from the old folio to the
new one during migration.  This makes original allocation sites persist
cross migration rather than lump into the get_new_folio callbacks passed
into migrate_pages(), e.g., compaction_alloc():

  # echo 1 >/proc/sys/vm/compact_memory
  # grep compaction_alloc /proc/allocinfo

Before this patch:
  132968448  32463  mm/compaction.c:1880 func:compaction_alloc

After this patch:
          0      0  mm/compaction.c:1880 func:compaction_alloc

Link: https://lkml.kernel.org/r/[email protected]
Fixes: dcfe378c81f7 ("lib: introduce support for page allocation tagging")
Signed-off-by: Yu Zhao <[email protected]>
Acked-by: Suren Baghdasaryan <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions