From: Ridong Chen lru_gen_folio_seq() computes how many generations below max_seq a folio should be added to, but stores it in a variable named "gen". Elsewhere in MGLRU "gen" means an index into lrugen->folios[], i.e. seq % MAX_NR_GENS, so reusing the name for a relative offset is confusing. The comment table above the code also no longer matches it. It only covers the PG_active and the final branch, leaving out the reclaiming and "can't evict yet" cases, and it lists LRU_REFS_FLAGS as an input although lru_gen_folio_seq() never looks at it. Rename the local variable to "age", redraw the table so that each branch maps to the age and seq it produces, and note that the result is clamped to min_seq[type]. No functional change. Assisted-by: LLM Signed-off-by: Ridong Chen --- include/linux/mm_inline.h | 48 ++++++++++++++++++++++++++------------- 1 file changed, 32 insertions(+), 16 deletions(-) diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index ab69b9930893..a933d8c14558 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -302,34 +302,50 @@ static inline unsigned long lru_gen_folio_seq(const struct lruvec *lruvec, const struct folio *folio, bool reclaiming) { - int gen; + int age; int type = folio_is_file_lru(folio); const struct lru_gen_folio *lrugen = &lruvec->lrugen; /* - * +-----------------------------------+-----------------------------------+ - * | Accessed through page tables and | Accessed through file descriptors | - * | promoted by folio_update_gen() | and protected by folio_inc_gen() | - * +-----------------------------------+-----------------------------------+ - * | PG_active (set while isolated) | | - * +-----------------+-----------------+-----------------+-----------------+ - * | PG_workingset | PG_referenced | PG_workingset | LRU_REFS_FLAGS | - * +-----------------------------------+-----------------------------------+ - * |<---------- MIN_NR_GENS ---------->| | - * |<---------------------------- MAX_NR_GENS ---------------------------->| + * +-----------------+-----------------+-----------------+-----------------+ + * age | 1 | 2 | 3 | 4 | + * +-----------------+-----------------+-----------------+-----------------+ + * seq | max_seq | max_seq-1 | max_seq-2 | max_seq-3 | + * +-----------------------------------+-----------------------------------+ + * |<---------- MIN_NR_GENS ---------->| | + * |<---------------------------- MAX_NR_GENS ---------------------------->| + * +-----------------------------------+-----------------------------------+ + * | Accessed through page tables and | Accessed through file descriptors | + * | promoted by folio_update_gen() | and protected by folio_inc_gen() | + * +-----------------+-----------------+-----------------+-----------------+ + * PG_active | PG_workingset | !PG_workingset | | | + * +-----------------+-----------------+-----------------+-----------------+ + * reclaiming | | | | always | + * +-----------------+-----------------+-----------------+-----------------+ + * can't | | anon && not in | | | + * evict yet | | swapcache, or | | | + * | | PG_reclaim && | | | + * | | dirty/writeback | | | + * +-----------------+-----------------+-----------------+-----------------+ + * else | | | PG_workingset | !PG_workingset | + * | | | or | && | + * | | | PG_referenced | !PG_referenced | + * +-----------------+-----------------+-----------------+-----------------+ + * + * The resulting seq is clamped to min_seq[type]. */ if (folio_test_active(folio)) - gen = MIN_NR_GENS - folio_test_workingset(folio); + age = MIN_NR_GENS - folio_test_workingset(folio); else if (reclaiming) - gen = MAX_NR_GENS; + age = MAX_NR_GENS; else if ((!folio_is_file_lru(folio) && !folio_test_swapcache(folio)) || (folio_test_reclaim(folio) && (folio_test_dirty(folio) || folio_test_writeback(folio)))) - gen = MIN_NR_GENS; + age = MIN_NR_GENS; else - gen = MAX_NR_GENS - (folio_test_workingset(folio) || folio_test_referenced(folio)); + age = MAX_NR_GENS - (folio_test_workingset(folio) || folio_test_referenced(folio)); - return max(READ_ONCE(lrugen->max_seq) - gen + 1, READ_ONCE(lrugen->min_seq[type])); + return max(READ_ONCE(lrugen->max_seq) - age + 1, READ_ONCE(lrugen->min_seq[type])); } static inline bool lru_gen_add_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming) -- 2.34.1