linux-kernel - [RFC PATCH 01/11] mm: khugepaged: add khugepaged_max_ptes_none check in collapse

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Message-ID: <aa2db6af6bb2124ef59ad5665951e47806c00a6e.1755677674.git.baolin.wang@linux.alibaba.com>
Date: Wed, 20 Aug 2025 17:07:12 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: akpm@...ux-foundation.org,
	hughd@...gle.com,
	david@...hat.com,
	lorenzo.stoakes@...cle.com
Cc: ziy@...dia.com,
	Liam.Howlett@...cle.com,
	npache@...hat.com,
	ryan.roberts@....com,
	dev.jain@....com,
	baohua@...nel.org,
	baolin.wang@...ux.alibaba.com,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH 01/11] mm: khugepaged: add khugepaged_max_ptes_none check in collapse_file()

Similar to the anonymous folios collapse, we should also check the 'khugepaged_max_ptes_none'
when trying to collapse shmem/file folios.

Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
---
 mm/khugepaged.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 5a3386043f39..5d4493b77f3c 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2125,6 +2125,13 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
 					}
 				}
 				nr_none++;
+
+				if (cc->is_khugepaged && nr_none > khugepaged_max_ptes_none) {
+					result = SCAN_EXCEED_NONE_PTE;
+					count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
+					goto xa_locked;
+				}
+
 				index++;
 				continue;
 			}
-- 
2.43.5