+ mm-khugepaged-replace-mutex_lock-mutex_unlock-usage-with-guard-macro.patch added to mm-unstable branch

The patch titled
     Subject: mm/khugepaged: replace mutex_lock/mutex_unlock usage with guard macro
has been added to the -mm mm-unstable branch.  Its filename is
     mm-khugepaged-replace-mutex_lock-mutex_unlock-usage-with-guard-macro.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-khugepaged-replace-mutex_lock-mutex_unlock-usage-with-guard-macro.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Jakov Novak <[email protected]>
Subject: mm/khugepaged: replace mutex_lock/mutex_unlock usage with guard macro
Date: Thu, 30 Jul 2026 22:47:24 +0200

Currently, khugepaged locks the khugepaged_mutex in two functions:
start_stop_khugepaged and khugepaged_min_free_kbytes_update.  Remove
mutex_lock/mutex_unlock usage in these functions and replace it with the
guard macro.  This makes the code more readable (removing a goto
statement) and makes it harder to introduce bugs in the future.  No
functional changes introduced.

Link: https://lore.kernel.org/[email protected]
Signed-off-by: Jakov Novak <[email protected]>
Reviewed-by: Dev Jain <[email protected]>
Reviewed-by: Lorenzo Stoakes (ARM) <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Reviewed-by: Zi Yan <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: Barry Song <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Lance Yang <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Nico Pache <[email protected]>
Cc: Ryan Roberts <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 mm/khugepaged.c |   31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

--- a/mm/khugepaged.c~mm-khugepaged-replace-mutex_lock-mutex_unlock-usage-with-guard-macro
+++ a/mm/khugepaged.c
@@ -23,6 +23,7 @@
 #include <linux/ksm.h>
 #include <linux/pgalloc.h>
 #include <linux/backing-dev.h>
+#include <linux/cleanup.h>
 
 #include <asm/tlb.h>
 #include "internal.h"
@@ -3115,18 +3116,19 @@ update_wmarks:
 
 int start_stop_khugepaged(void)
 {
-	int err = 0;
-
-	mutex_lock(&khugepaged_mutex);
+	guard(mutex)(&khugepaged_mutex);
 	if (hugepage_enabled()) {
-		if (!khugepaged_thread)
-			khugepaged_thread = kthread_run(khugepaged, NULL,
-							"khugepaged");
-		if (IS_ERR(khugepaged_thread)) {
-			pr_err("khugepaged: kthread_run(khugepaged) failed\n");
-			err = PTR_ERR(khugepaged_thread);
-			khugepaged_thread = NULL;
-			goto fail;
+		if (!khugepaged_thread) {
+			struct task_struct *new_thread = kthread_run(khugepaged,
+								     NULL,
+								     "khugepaged");
+
+			if (IS_ERR(new_thread)) {
+				pr_err("khugepaged: kthread_run(khugepaged) failed\n");
+				return PTR_ERR(new_thread);
+			}
+
+			khugepaged_thread = new_thread;
 		}
 
 		if (!list_empty(&khugepaged_scan.mm_head))
@@ -3136,17 +3138,14 @@ int start_stop_khugepaged(void)
 		khugepaged_thread = NULL;
 	}
 	set_recommended_min_free_kbytes();
-fail:
-	mutex_unlock(&khugepaged_mutex);
-	return err;
+	return 0;
 }
 
 void khugepaged_min_free_kbytes_update(void)
 {
-	mutex_lock(&khugepaged_mutex);
+	guard(mutex)(&khugepaged_mutex);
 	if (hugepage_enabled() && khugepaged_thread)
 		set_recommended_min_free_kbytes();
-	mutex_unlock(&khugepaged_mutex);
 }
 
 bool current_is_khugepaged(void)
_

Patches currently in -mm which might be from [email protected] are

mm-khugepaged-replace-mutex_lock-mutex_unlock-usage-with-guard-macro.patch