[PATCH v8 03/15] khugepaged: generalize hugepage_vma_revalidate for mTHP support

[Nico Pache]

For khugepaged to support different mTHP orders, we must generalize this
to check if the PMD is not shared by another VMA and the order is enabled.

To ensure madvise_collapse can support working on mTHP orders without the
PMD order enabled, we need to convert hugepage_vma_revalidate to take a
bitmap of orders.

No functional change in this patch.

Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Co-developed-by: Dev Jain <dev.jain@xxxxxxx>
Signed-off-by: Dev Jain <dev.jain@xxxxxxx>
Signed-off-by: Nico Pache <npache@xxxxxxxxxx>
---
 mm/khugepaged.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index bf69e81a3d82..7bcd4d280c71 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -907,7 +907,7 @@ static int khugepaged_find_target_node(struct collapse_control *cc)
 static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
 				   bool expect_anon,
 				   struct vm_area_struct **vmap,
-				   struct collapse_control *cc)
+				   struct collapse_control *cc, unsigned long orders)
 {
 	struct vm_area_struct *vma;
 	unsigned long tva_flags = cc->is_khugepaged ? TVA_ENFORCE_SYSFS : 0;
@@ -919,9 +919,10 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
 	if (!vma)
 		return SCAN_VMA_NULL;
 
+	/* Always check the PMD order to insure its not shared by another VMA */
 	if (!thp_vma_suitable_order(vma, address, PMD_ORDER))
 		return SCAN_ADDRESS_RANGE;
-	if (!thp_vma_allowable_order(vma, vma->vm_flags, tva_flags, PMD_ORDER))
+	if (!thp_vma_allowable_orders(vma, vma->vm_flags, tva_flags, orders))
 		return SCAN_VMA_CHECK;
 	/*
 	 * Anon VMA expected, the address may be unmapped then
@@ -1115,7 +1116,8 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
 		goto out_nolock;
 
 	mmap_read_lock(mm);
-	result = hugepage_vma_revalidate(mm, address, true, &vma, cc);
+	result = hugepage_vma_revalidate(mm, address, true, &vma, cc,
+					 BIT(HPAGE_PMD_ORDER));
 	if (result != SCAN_SUCCEED) {
 		mmap_read_unlock(mm);
 		goto out_nolock;
@@ -1149,7 +1151,8 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
 	 * mmap_lock.
 	 */
 	mmap_write_lock(mm);
-	result = hugepage_vma_revalidate(mm, address, true, &vma, cc);
+	result = hugepage_vma_revalidate(mm, address, true, &vma, cc,
+					 BIT(HPAGE_PMD_ORDER));
 	if (result != SCAN_SUCCEED)
 		goto out_up_write;
 	/* check if the pmd is still valid */
@@ -2780,7 +2783,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start,
 			mmap_read_lock(mm);
 			mmap_locked = true;
 			result = hugepage_vma_revalidate(mm, addr, false, &vma,
-							 cc);
+							 cc, BIT(HPAGE_PMD_ORDER));
 			if (result  != SCAN_SUCCEED) {
 				last_fail = result;
 				goto out_nolock;
-- 
2.49.0