linux-kernel - [RFC 10/11] khugepaged: remove max_ptes

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Message-ID: <20250108233128.14484-11-npache@redhat.com>
Date: Wed,  8 Jan 2025 16:31:26 -0700
From: Nico Pache <npache@...hat.com>
To: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
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Subject: [RFC 10/11] khugepaged: remove max_ptes_none restriction on the pmd scan

now that we have mTHP support, which uses max_ptes_none to determine how
"full" a mTHP size needs to collapse. lets remove the restriction during
the scan phase so we dont bailout early and miss potential mTHP
candidates.

Signed-off-by: Nico Pache <npache@...hat.com>
---
 mm/khugepaged.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 4d3c560f20b4..61a349eb3cf4 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1446,15 +1446,12 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
 		if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
 			all_valid = false;
 			++none_or_zero;
-			if (!userfaultfd_armed(vma) &&
-			    (!cc->is_khugepaged ||
-			     none_or_zero <= khugepaged_max_ptes_none)) {
-				continue;
-			} else {
+			if (userfaultfd_armed(vma)) {
 				result = SCAN_EXCEED_NONE_PTE;
 				count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
 				goto out_unmap;
 			}
+			continue;
 		}
 		if (pte_uffd_wp(pteval)) {
 			/*
-- 
2.47.1