[PATCH 7.2 v16 09/13] mm/khugepaged: introduce collapse_allowable_orders helper function

Nico Pache
2026-04-19T19:01:18Z

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>
---
include/linux/khugepaged.h | 6 ++----
mm/huge_memory.c | 2 +-
mm/khugepaged.c | 20 ++++++++++++++------
mm/vma.c | 6 +++---
tools/testing/vma/include/stubs.h | 3 +--
5 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
index d7a9053ff4fe..e87df2fa6931 100644
--- a/include/linux/khugepaged.h
+++ b/include/linux/khugepaged.h
@@ -13,8 +13,7 @@ extern void khugepaged_destroy(void);
extern int start_stop_khugepaged(void);
extern void __khugepaged_enter(struct mm_struct *mm);
extern void __khugepaged_exit(struct mm_struct *mm);
-extern void khugepaged_enter_vma(struct vm_area_struct *vma,
- vm_flags_t vm_flags);
+extern void khugepaged_enter_vma(struct vm_area_struct *vma);
extern void khugepaged_min_free_kbytes_update(void);
extern bool current_is_khugepaged(void);
void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
@@ -38,8 +37,7 @@ static inline void khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm
static inline void khugepaged_exit(struct mm_struct *mm)
{
}
-static inline void khugepaged_enter_vma(struct vm_area_struct *vma,
- vm_flags_t vm_flags)
+static inline void khugepaged_enter_vma(struct vm_area_struct *vma)
{
}
static inline void collapse_pte_mapped_thp(struct mm_struct *mm,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 5c128cdec810..1023698a8b96 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1557,7 +1557,7 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
ret = vmf_anon_prepare(vmf);
if (ret)
return ret;
- khugepaged_enter_vma(vma, vma->vm_flags);
+ khugepaged_enter_vma(vma);

if (!(vmf->flags & FAULT_FLAG_WRITE) &&
!mm_forbids_zeropage(vma->vm_mm) &&
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index a4f1c570b69b..fdbdc1a1cdd9 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -447,7 +447,7 @@ int hugepage_madvise(struct vm_area_struct *vma,
* register it here without waiting a page fault that
* may not happen any time soon.
*/
- khugepaged_enter_vma(vma, *vm_flags);
+ khugepaged_enter_vma(vma);
break;
case MADV_NOHUGEPAGE:
*vm_flags &= ~VM_HUGEPAGE;
@@ -546,12 +546,20 @@ void __khugepaged_enter(struct mm_struct *mm)
wake_up_interruptible(&khugepaged_wait);
}

-void khugepaged_enter_vma(struct vm_area_struct *vma,
- vm_flags_t vm_flags)
+/* Check what orders are allowed based on the vma and collapse type */
+static unsigned long collapse_allowable_orders(struct vm_area_struct *vma,
+ enum tva_type tva_flags)
+{
+ unsigned long orders = BIT(HPAGE_PMD_ORDER);
+
+ return thp_vma_allowable_orders(vma, vma->vm_flags, tva_flags, orders);
+}
+
+void khugepaged_enter_vma(struct vm_area_struct *vma)
{
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, TVA_KHUGEPAGED))
__khugepaged_enter(vma->vm_mm);
}
}
@@ -2664,7 +2672,7 @@ static void collapse_scan_mm_slot(unsigned int progress_max,
cc->progress++;
break;
}
- if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) {
+ if (!collapse_allowable_orders(vma, TVA_KHUGEPAGED)) {
cc->progress++;
continue;
}
@@ -2973,7 +2981,7 @@ 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, TVA_FORCED_COLLAPSE))
return -EINVAL;

cc = kmalloc_obj(*cc);
diff --git a/mm/vma.c b/mm/vma.c
index 377321b48734..c0398fb597b3 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -989,7 +989,7 @@ static __must_check struct vm_area_struct *vma_merge_existing_range(
goto abort;

vma_set_flags_mask(vmg->target, sticky_flags);
- khugepaged_enter_vma(vmg->target, vmg->vm_flags);
+ khugepaged_enter_vma(vmg->target);
vmg->state = VMA_MERGE_SUCCESS;
return vmg->target;

@@ -1110,7 +1110,7 @@ struct vm_area_struct *vma_merge_new_range(struct vma_merge_struct *vmg)
* following VMA if we have VMAs on both sides.
*/
if (vmg->target && !vma_expand(vmg)) {
- khugepaged_enter_vma(vmg->target, vmg->vm_flags);
+ khugepaged_enter_vma(vmg->target);
vmg->state = VMA_MERGE_SUCCESS;
return vmg->target;
}
@@ -2589,7 +2589,7 @@ static int __mmap_new_vma(struct mmap_state *map, struct vm_area_struct **vmap,
* call covers the non-merge case.
*/
if (!vma_is_anonymous(vma))
- khugepaged_enter_vma(vma, map->vm_flags);
+ khugepaged_enter_vma(vma);
*vmap = vma;
return 0;

diff --git a/tools/testing/vma/include/stubs.h b/tools/testing/vma/include/stubs.h
index a30b8bc84955..3d9a2daa2712 100644
--- a/tools/testing/vma/include/stubs.h
+++ b/tools/testing/vma/include/stubs.h
@@ -182,8 +182,7 @@ static inline bool mpol_equal(struct mempolicy *a, struct mempolicy *b)
return true;
}

-static inline void khugepaged_enter_vma(struct vm_area_struct *vma,
- vm_flags_t vm_flags)
+static inline void khugepaged_enter_vma(struct vm_area_struct *vma)
{
}

--
2.53.0