linux-kernel - [PATCH] mm/page_owner.c: use get_task_comm() to record task command name with the protection of task

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Message-Id: <20220420122817.67181-1-caoyixuan2019@email.szu.edu.cn>
Date:   Wed, 20 Apr 2022 20:28:17 +0800
From:   Yixuan Cao <caoyixuan2019@...il.szu.edu.cn>
To:     akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        zhangyinan2019@...il.szu.edu.cn, yejiajian2018@...il.szu.edu.cn,
        hanshenghong2019@...il.szu.edu.cn,
        zhaochongxi2019@...il.szu.edu.cn,
        Yixuan Cao <caoyixuan2019@...il.szu.edu.cn>
Subject: [PATCH] mm/page_owner.c: use get_task_comm() to record task command name with the protection of task_lock()

I noticed that it is advised to access task command name with
[gs]et_task_comm() in the comment of task_struct->comm,
which is safer with the protection of task_lock().

Relative comment in include/linux/sched.h is as follows:

/*
 * executable name, excluding path.
 *
 * - normally initialized setup_new_exec()
 * - access it with [gs]et_task_comm()
 * - lock it with task_lock()
*/

Signed-off-by: Yixuan Cao <caoyixuan2019@...il.szu.edu.cn>
---
 mm/page_owner.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/page_owner.c b/mm/page_owner.c
index 2743062e92c2..bda8fe2660c0 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -171,8 +171,7 @@ static inline void __set_page_owner_handle(struct page_ext *page_ext,
 		page_owner->pid = current->pid;
 		page_owner->tgid = current->tgid;
 		page_owner->ts_nsec = local_clock();
-		strlcpy(page_owner->comm, current->comm,
-			sizeof(page_owner->comm));
+		get_task_comm(page_owner->comm, current);
 		__set_bit(PAGE_EXT_OWNER, &page_ext->flags);
 		__set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
 
-- 
2.17.1