[RFC PATCH 04/57] mm/collapse: rename mthp_present_ptes to eligible_ptes
From: Kiryl Shutsemau <hidden>
Date: 2026-08-16 22:46:26
Also in:
bpf, linux-kselftest, linux-mm, lkml
Subsystem:
memory management, memory management - thp (transparent huge page), the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
From: "Kiryl Shutsemau (Meta)" <kas@kernel.org> Neither half of the name holds. A bit is set only after the PTE has passed every check the scan makes: uffd, lazyfree, anonymity and sharing among them. Presence is the first of those criteria, not the whole of it. mthp_collapse() then reads the bitmap starting at the PMD order, so the bitmap is not specific to mTHP either. Name the bitmap for what a set bit means: the scan accepted that PTE as a collapse source. No functional change. Assisted-by: Claude-Code:claude-opus-5 Signed-off-by: Kiryl Shutsemau (Meta) <kas@kernel.org> --- mm/collapse.h | 4 ++-- mm/khugepaged.c | 13 ++++++------- 2 files changed, 8 insertions(+), 9 deletions(-)
diff --git a/mm/collapse.h b/mm/collapse.h
index 26dbac7beddd..9c82e71533df 100644
--- a/mm/collapse.h
+++ b/mm/collapse.h@@ -53,8 +53,8 @@ struct collapse_control { /* nodemask for allocation fallback */ nodemask_t alloc_nmask; - /* Each bit represents a single occupied (!none/zero) page. */ - DECLARE_BITMAP(mthp_present_ptes, MAX_PTRS_PER_PTE); + /* Each bit marks a PTE the scan accepted as a collapse source */ + DECLARE_BITMAP(eligible_ptes, MAX_PTRS_PER_PTE); }; #endif /* __MM_COLLAPSE_H */
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 804b1d35f52a..a12aafae8d9c 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c@@ -576,7 +576,7 @@ static void collapse_control_init_scan(struct collapse_control *cc) { memset(cc->node_load, 0, sizeof(cc->node_load)); nodes_clear(cc->alloc_nmask); - bitmap_zero(cc->mthp_present_ptes, MAX_PTRS_PER_PTE); + bitmap_zero(cc->eligible_ptes, MAX_PTRS_PER_PTE); } static void release_pte_folio(struct folio *folio)
@@ -1437,8 +1437,8 @@ static unsigned int max_order_from_offset(unsigned int offset) * mthp_collapse() consumes the bitmap that is generated during * collapse_scan_pmd() to determine what regions and mTHP orders fit best. * - * Each bit in cc->mthp_present_ptes represents a single occupied (!none/zero) - * page. We start at the PMD order and check if it is eligible for collapse; + * Each bit in cc->eligible_ptes marks a PTE the scan accepted as a collapse + * source. We start at the PMD order and check if it is eligible for collapse; * if not, we check the left and right halves of the PTE page table we are * examining at a lower order. *
@@ -1469,12 +1469,12 @@ static enum scan_result mthp_collapse(struct mm_struct *mm, goto next_order; max_ptes_none = collapse_max_ptes_none(cc, NULL, order); - nr_occupied_ptes = bitmap_weight_from(cc->mthp_present_ptes, offset, + nr_occupied_ptes = bitmap_weight_from(cc->eligible_ptes, offset, offset + nr_ptes); /* * Swap PTEs accepted during the scan are counted in @unmapped, - * not in the present-PTE bitmap. Account them for the PMD-order + * not in the eligible bitmap. Account them for the PMD-order * candidate. */ if (is_pmd_order(order))
@@ -1682,8 +1682,7 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm, } } - /* Set bit for occupied pages */ - __set_bit(i, cc->mthp_present_ptes); + __set_bit(i, cc->eligible_ptes); /* * Record which node the original page is from and save this * information to cc->node_load[].
--
2.54.0