[PATCH v6 4/6] mm/mglru: move max_seq read into walk_update_folio
From: Kairui Song via B4 Relay <devnull+kasong.tencent.com@kernel.org>
Date: 2026-09-05 16:51:14
Also in:
b4-sent, linux-mm, lkml
Subsystem:
memory management, memory management - mglru (multi-gen lru), memory management - reclaim, the rest · Maintainers:
Andrew Morton, Johannes Weiner, Linus Torvalds
From: Kairui Song <kasong@tencent.com> walk_pte_range(), walk_pmd_range_locked(), and lru_gen_look_around() each read lrugen->max_seq to compute the target generation used by walk_update_folio(), then pass it as a parameter. Move the read into walk_update_folio() itself so the callers no longer need to compute or pass the value. The max_seq read now happens once per folio update rather than once per walk range, so folios always get promoted to the current youngest generation. Reviewed-by: Baoquan He <baoquan.he@linux.dev> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Ridong Chen <ridong.chen@linux.dev> Reviewed-by: Lian Wang <redacted> Reviewed-by: Barry Song <baohua@kernel.org> Signed-off-by: Kairui Song <kasong@tencent.com> --- mm/vmscan.c | 29 ++++++++++++----------------- 1 file changed, 12 insertions(+), 17 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index c6e03a5047ae..4732b987aa67 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c@@ -3557,13 +3557,15 @@ static bool suitable_to_scan(int total, int young) } static void walk_update_folio(struct lru_gen_mm_walk *walk, struct vm_area_struct *vma, - struct folio *folio, int new_gen, bool dirty) + struct lruvec *lruvec, struct folio *folio, bool dirty) { - int old_gen; + int new_gen, old_gen; if (!folio) return; + new_gen = lru_gen_from_seq(READ_ONCE(lruvec->lrugen.max_seq)); + if (dirty && !folio_test_dirty(folio) && !(folio_test_anon(folio) && folio_test_swapbacked(folio) && !folio_test_swapcache(folio)))
@@ -3594,8 +3596,6 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end, struct lru_gen_mm_walk *walk = args->private; struct mem_cgroup *memcg = lruvec_memcg(walk->lruvec); struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec); - DEFINE_MAX_SEQ(walk->lruvec); - int gen = lru_gen_from_seq(max_seq); unsigned int nr; pmd_t pmdval;
@@ -3646,7 +3646,7 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end, continue; if (last != folio) { - walk_update_folio(walk, args->vma, last, gen, dirty); + walk_update_folio(walk, args->vma, walk->lruvec, last, dirty); last = folio; dirty = false;
@@ -3659,7 +3659,7 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end, walk->mm_stats[MM_LEAF_YOUNG] += nr; } - walk_update_folio(walk, args->vma, last, gen, dirty); + walk_update_folio(walk, args->vma, walk->lruvec, last, dirty); last = NULL; if (i < PTRS_PER_PTE && get_next_vma(PMD_MASK, PAGE_SIZE, args, &start, &end))
@@ -3682,8 +3682,6 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area struct lru_gen_mm_walk *walk = args->private; struct mem_cgroup *memcg = lruvec_memcg(walk->lruvec); struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec); - DEFINE_MAX_SEQ(walk->lruvec); - int gen = lru_gen_from_seq(max_seq); VM_WARN_ON_ONCE(pud_leaf(*pud));
@@ -3737,7 +3735,7 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area goto next; if (last != folio) { - walk_update_folio(walk, vma, last, gen, dirty); + walk_update_folio(walk, vma, walk->lruvec, last, dirty); last = folio; dirty = false;
@@ -3751,7 +3749,7 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area i = i > MIN_LRU_BATCH ? 0 : find_next_bit(bitmap, MIN_LRU_BATCH, i) + 1; } while (i <= MIN_LRU_BATCH); - walk_update_folio(walk, vma, last, gen, dirty); + walk_update_folio(walk, vma, walk->lruvec, last, dirty); lazy_mmu_mode_disable(); spin_unlock(ptl);
@@ -4357,8 +4355,6 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr) struct pglist_data *pgdat = folio_pgdat(folio); struct lruvec *lruvec; struct lru_gen_mm_state *mm_state; - unsigned long max_seq; - int gen; lockdep_assert_held(pvmw->ptl); VM_WARN_ON_ONCE_FOLIO(folio_test_lru(folio), folio);
@@ -4395,8 +4391,6 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr) memcg = get_mem_cgroup_from_folio(folio); lruvec = mem_cgroup_lruvec(memcg, pgdat); - max_seq = READ_ONCE((lruvec)->lrugen.max_seq); - gen = lru_gen_from_seq(max_seq); mm_state = get_mm_state(lruvec); lazy_mmu_mode_enable();
@@ -4428,7 +4422,7 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr) continue; if (last != folio) { - walk_update_folio(walk, vma, last, gen, dirty); + walk_update_folio(walk, vma, lruvec, last, dirty); last = folio; dirty = false;
@@ -4440,13 +4434,14 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr) young += nr; } - walk_update_folio(walk, vma, last, gen, dirty); + walk_update_folio(walk, vma, lruvec, last, dirty); lazy_mmu_mode_disable(); /* feedback from rmap walkers to page table walkers */ if (mm_state && suitable_to_scan(i, young)) - update_bloom_filter(mm_state, max_seq, pvmw->pmd); + update_bloom_filter(mm_state, READ_ONCE(lruvec->lrugen.max_seq), + pvmw->pmd); mem_cgroup_put(memcg);
--
2.55.0