linux-kernel - [PATCH v2 15/17] khugepaged: Delay cond

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Message-Id: <20250211111326.14295-16-dev.jain@arm.com>
Date: Tue, 11 Feb 2025 16:43:24 +0530
From: Dev Jain <dev.jain@....com>
To: akpm@...ux-foundation.org,
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	Dev Jain <dev.jain@....com>
Subject: [PATCH v2 15/17] khugepaged: Delay cond_resched()

Post scanning VMAs less than PMD-size, cond_resched() may get called at
a frequency of 1 << order worth of pte scan. Earlier, this was at a
PMD-worth scan. Therefore, manually enforce the previous behaviour; not
doing this causes the khugepaged selftest to timeout.

Signed-off-by: Dev Jain <dev.jain@....com>
---
 mm/khugepaged.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 7c9a758f6817..d2bb008b95e7 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2650,6 +2650,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
 	unsigned long orders;
 	int order;
 	bool is_file_vma;
+	int prev_progress = 0;
 
 	VM_BUG_ON(!pages);
 	lockdep_assert_held(&khugepaged_mm_lock);
@@ -2730,7 +2731,10 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
 		while (khugepaged_scan.address < hend) {
 			bool mmap_locked = true;
 
-			cond_resched();
+			if (progress - prev_progress >= HPAGE_PMD_NR) {
+				cond_resched();
+				prev_progress = progress;
+			}
 			if (unlikely(hpage_collapse_test_exit_or_disable(mm)))
 				goto breakouterloop;
 
-- 
2.30.2