[PATCH mm-unstable v14 12/16] khugepaged: introduce collapse_allowable_orders helper function
From: Nico Pache <npache@redhat.com>
Date: 2026-01-22 19:32:05
Also in:
linux-doc, linux-mm, lkml
Subsystem:
memory management, memory management - thp (transparent huge page), the rest · Maintainers:
Andrew Morton, David Hildenbrand, Lorenzo Stoakes, Linus Torvalds
Add collapse_allowable_orders() to generalize THP order eligibility. The function determines which THP orders are permitted based on collapse context (khugepaged vs madv_collapse). This consolidates collapse configuration logic and provides a clean interface for future mTHP collapse support where the orders may be different. Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Signed-off-by: Nico Pache <npache@redhat.com> --- mm/khugepaged.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index e33b2594949d..11eedd261285 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c@@ -498,12 +498,22 @@ static unsigned int collapse_max_ptes_none(unsigned int order, bool full_scan) return -EINVAL; } +/* Check what orders are allowed based on the vma and collapse type */ +static unsigned long collapse_allowable_orders(struct vm_area_struct *vma, + vm_flags_t vm_flags, bool is_khugepaged) +{ + enum tva_type tva_flags = is_khugepaged ? TVA_KHUGEPAGED : TVA_FORCED_COLLAPSE; + unsigned long orders = BIT(HPAGE_PMD_ORDER); + + return thp_vma_allowable_orders(vma, vm_flags, tva_flags, orders); +} + void khugepaged_enter_vma(struct vm_area_struct *vma, vm_flags_t vm_flags) { if (!mm_flags_test(MMF_VM_HUGEPAGE, vma->vm_mm) && hugepage_pmd_enabled()) { - if (thp_vma_allowable_order(vma, vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) + if (collapse_allowable_orders(vma, vm_flags, /*is_khugepaged=*/true)) __khugepaged_enter(vma->vm_mm); } }
@@ -2610,7 +2620,7 @@ static unsigned int collapse_scan_mm_slot(unsigned int pages, enum scan_result * progress++; break; } - if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) { + if (!collapse_allowable_orders(vma, vma->vm_flags, /*is_khugepaged=*/true)) { progress++; continue; }
@@ -2920,7 +2930,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, BUG_ON(vma->vm_start > start); BUG_ON(vma->vm_end < end); - if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_FORCED_COLLAPSE, PMD_ORDER)) + if (!collapse_allowable_orders(vma, vma->vm_flags, /*is_khugepaged=*/false)) return -EINVAL; cc = kmalloc(sizeof(*cc), GFP_KERNEL);
--
2.52.0