From fc4f15ee0bcd56f40ad1df723ac9889d7e82f5a0 Mon Sep 17 00:00:00 2001 From: Wei Yang Date: Tue, 21 Oct 2025 21:21:41 +0000 Subject: [PATCH] mm/huge_memory: optimize and simplify folio stat update after split The loop executed after a successful folio split currently has two combined responsibilities: * updating statistics for the new folios * determining the folio for the next split iteration. This commit refactors the logic to directly calculate and update folio statistics, eliminating the need for the iteration step. We can do this because all necessary information is already available: * All resulting new folios have the same order, which is @split_order. * The exact number of new folios can be calculated directly using @old_order and @split_order. * The folio for the subsequent split is simply the one containing @split_at. By leveraging this knowledge, we can achieve the stat update more cleanly and efficiently without the looping logic. Link: https://lkml.kernel.org/r/20251021212142.25766-4-richard.weiyang@gmail.com Signed-off-by: Wei Yang Acked-by: David Hildenbrand Reviewed-by: Zi Yan Reviewed-by: wang lian Reviewed-by: Lorenzo Stoakes Cc: Baolin Wang Cc: Barry Song Cc: Dev Jain Cc: Lance Yang Cc: Liam Howlett Cc: Mariano Pache Cc: Ryan Roberts Signed-off-by: Andrew Morton --- mm/huge_memory.c | 18 ++++-------------- 1 file changed, 4 insertions(+), 14 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 85c472fbcbfa5..52c4114a17f29 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3404,7 +3404,6 @@ static int __split_unmapped_folio(struct folio *folio, int new_order, const bool is_anon = folio_test_anon(folio); int order = folio_order(folio); int start_order = uniform_split ? new_order : order - 1; - struct folio *next; int split_order; /* @@ -3414,9 +3413,8 @@ static int __split_unmapped_folio(struct folio *folio, int new_order, for (split_order = start_order; split_order >= new_order; split_order--) { - struct folio *end_folio = folio_next(folio); int old_order = folio_order(folio); - struct folio *new_folio; + int nr_new_folios = 1UL << (old_order - split_order); /* order-1 anonymous folio is not supported */ if (is_anon && split_order == 1) @@ -3445,19 +3443,11 @@ static int __split_unmapped_folio(struct folio *folio, int new_order, pgalloc_tag_split(folio, old_order, split_order); __split_folio_to_order(folio, old_order, split_order); - if (is_anon) + if (is_anon) { mod_mthp_stat(old_order, MTHP_STAT_NR_ANON, -1); - /* - * Iterate through after-split folios and update folio stats. - */ - for (new_folio = folio; new_folio != end_folio; new_folio = next) { - next = folio_next(new_folio); - if (new_folio == page_folio(split_at)) - folio = new_folio; - if (is_anon) - mod_mthp_stat(folio_order(new_folio), - MTHP_STAT_NR_ANON, 1); + mod_mthp_stat(split_order, MTHP_STAT_NR_ANON, nr_new_folios); } + folio = page_folio(split_at); } return 0; -- 2.47.3