linux-kernel - [PATCH 1/1] mm/khugepaged: keep mm in mm_slot without MMF_DISABLE

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Date: Tue, 27 Feb 2024 11:51:35 +0800
From: Lance Yang <ioworker0@...il.com>
To: akpm@...ux-foundation.org
Cc: shy828301@...il.com,
	mhocko@...e.com,
	zokeefe@...gle.com,
	david@...hat.com,
	songmuchun@...edance.com,
	peterx@...hat.com,
	minchan@...nel.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Lance Yang <ioworker0@...il.com>
Subject: [PATCH 1/1] mm/khugepaged: keep mm in mm_slot without MMF_DISABLE_THP check

Previously, we removed the mm from mm_slot and dropped mm_count
if the MMF_THP_DISABLE flag was set. However, we didn't re-add
the mm back after clearing the MMF_THP_DISABLE flag. Additionally,
We add a check for the MMF_THP_DISABLE flag in hugepage_vma_revalidate().

Fixes: 879c6000e191 ("mm/khugepaged: bypassing unnecessary scans with MMF_DISABLE_THP check")

Signed-off-by: Lance Yang <ioworker0@...il.com>
Suggested-by: Yang Shi <shy828301@...il.com>
---
 mm/khugepaged.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 2771fc043b3b..1c0073daad82 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -920,7 +920,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
 {
 	struct vm_area_struct *vma;
 
-	if (unlikely(hpage_collapse_test_exit(mm)))
+	if (unlikely(hpage_collapse_test_exit_or_disable(mm)))
 		return SCAN_ANY_PROCESS;
 
 	*vmap = vma = find_vma(mm, address);
@@ -1428,7 +1428,7 @@ static void collect_mm_slot(struct khugepaged_mm_slot *mm_slot)
 
 	lockdep_assert_held(&khugepaged_mm_lock);
 
-	if (hpage_collapse_test_exit_or_disable(mm)) {
+	if (hpage_collapse_test_exit(mm)) {
 		/* free mm_slot */
 		hash_del(&slot->hash);
 		list_del(&slot->mm_node);
@@ -2456,7 +2456,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
 	 * Release the current mm_slot if this mm is about to die, or
 	 * if we scanned all vmas of this mm.
 	 */
-	if (hpage_collapse_test_exit_or_disable(mm) || !vma) {
+	if (hpage_collapse_test_exit(mm) || !vma) {
 		/*
 		 * Make sure that if mm_users is reaching zero while
 		 * khugepaged runs here, khugepaged_exit will find
-- 
2.33.1