Re: [PATCH v2 08/26] mm/fbatch: replace mlock_new_folio() by __folio_add_lru(,mlockit)

On 9/9/26 11:57, Hugh Dickins wrote:

Replace mlock_new_folio(), working on mm/mlock.c's mlock_fbatch, by
__folio_add_lru(,mlockit), working on mm/folio.c's lru_add fbatch:
folio moved to lruvec by lru_add(), with its mlocking incidental.

Remove old comment about not needing smp_mb__after_atomic() from
lru_add(): but that is a detail which will need to be reconsidered.

Initialize mlock_count earlier, when adding to fbatch rather than when
adding to lruvec. mlock_count count in 2s, with the low bit set to
distinguish it from lru.prev. This helps when an mlocked folio is put
back early by compaction, but will enable further optimization next.

Change mlock_count from unsigned int to long: long to match pointer
without endian concerns, signed for better treatment of those rare
cases when final munlocks precede their still batched mlocks.

This is an intermediate, poorly tested review stage: mlock_new_folio()
code removed from mm/mlock.c, remaining code there updated to respect
the new mlock_count accounting, but not considered beyond that.

Signed-off-by: Hugh Dickins <hughd@google.com>

Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>