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[92.242.248.69]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-498010aaceasm85398185e9.12.2026.07.30.13.48.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jul 2026 13:48:12 -0700 (PDT) From: Jakov Novak To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linux.dev, Andrew Morton , David Hildenbrand , Lorenzo Stoakes Cc: Zi Yan , Baolin Wang , "\\ Liam R . Howlett \\ " , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Shuah Khan , Jakov Novak Subject: [PATCH v3] mm/khugepaged: replace mutex_lock/mutex_unlock usage with guard macro Date: Thu, 30 Jul 2026 22:47:24 +0200 Message-ID: <20260730204724.16912-1-jakovnovak30@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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. Signed-off-by: Jakov Novak Reviewed-by: Dev Jain Reviewed-by: Lorenzo Stoakes (ARM) Reviewed-by: Andrew Morton Reviewed-by: Zi Yan --- v2: - Added #include to the includes at the top of the file - Moved err declaration to the scope where it's used in start_stop_khugepaged - Made default case return 0 instead of err in start_stop_khugepaged v3: - Moved new thread creation logic inside if (!khugepaged_thread) block in start_stop_khugepaged - Removed suboptimal err variable mm/khugepaged.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 617bca76db49..97f61a050f7c 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include "internal.h" @@ -3111,18 +3112,19 @@ void set_recommended_min_free_kbytes(void) 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)) @@ -3132,17 +3134,14 @@ 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) -- 2.55.0