Re: [PATCH v10 03/13] khugepaged: generalize hugepage_vma_revalidate for mTHP support
From: Lorenzo Stoakes <hidden>
Date: 2025-08-20 13:24:48
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On Tue, Aug 19, 2025 at 07:41:55AM -0600, Nico Pache wrote:
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@linux.alibaba.com> Acked-by: David Hildenbrand <redacted> Co-developed-by: Dev Jain <dev.jain@arm.com> Signed-off-by: Dev Jain <dev.jain@arm.com> Signed-off-by: Nico Pache <redacted>
LGTM (modulo nit/query below) so: Reviewed-by: Lorenzo Stoakes <redacted>
quoted hunk ↗ jump to hunk
--- mm/khugepaged.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)diff --git a/mm/khugepaged.c b/mm/khugepaged.c index b7b98aebb670..2d192ec961d2 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c@@ -917,7 +917,7 @@ static int collapse_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; enum tva_type type = cc->is_khugepaged ? TVA_KHUGEPAGED :@@ -930,9 +930,10 @@ 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 */
NIT: ensure not insure.
quoted hunk ↗ jump to hunk
if (!thp_vma_suitable_order(vma, address, PMD_ORDER)) return SCAN_ADDRESS_RANGE; - if (!thp_vma_allowable_order(vma, vma->vm_flags, type, PMD_ORDER)) + if (!thp_vma_allowable_orders(vma, vma->vm_flags, type, orders)) return SCAN_VMA_CHECK; /* * Anon VMA expected, the address may be unmapped then@@ -1134,7 +1135,8 @@ 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));
Shouldn't this be PMD order? Seems equivalent.
quoted hunk ↗ jump to hunk
if (result != SCAN_SUCCEED) { mmap_read_unlock(mm); goto out_nolock;@@ -1168,7 +1170,8 @@ 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 */@@ -2807,7 +2810,7 @@ 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; --2.50.1