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From: Yafang Shao <laoar.shao@gmail.com>
To: akpm@linux-foundation.org, pmladek@suse.com,
	peterz@infradead.org, valentin.schneider@arm.com,
	keescook@chromium.org, mathieu.desnoyers@efficios.com,
	qiang.zhang@windriver.com, robdclark@chromium.org,
	viro@zeniv.linux.org.uk, christian@brauner.io,
	dietmar.eggemann@arm.com
Cc: linux-kernel@vger.kernel.org, Yafang Shao <laoar.shao@gmail.com>
Subject: [PATCH 5/5] kernel/kthread: show a warning if kthread's comm is still trucated
Date: Wed, 29 Sep 2021 11:50:36 +0000	[thread overview]
Message-ID: <20210929115036.4851-6-laoar.shao@gmail.com> (raw)
In-Reply-To: <20210929115036.4851-1-laoar.shao@gmail.com>

Show a warning if the ktrhead's comm is still trucated. Below is the
result of my test case -

__kthread_create_on_node:410: comm of pid 14 is truncated from "I-am-a-kthread-with-long-name" to "I-am-a-kthread-with-lon"

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 kernel/kthread.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 6def951c605a..aa093f1f423a 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -404,7 +404,11 @@ struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data),
 		 * task is already visible to other tasks, so updating
 		 * COMM must be protected.
 		 */
-		vsnprintf(name, sizeof(name), namefmt, args);
+		if (vsnprintf(name, KTHREAD_COMM_LEN, namefmt, args) >=
+		    KTHREAD_COMM_LEN)
+			pr_warn("%s:%d: comm of pid %d is truncated from \"%s\" to \"%s\"\n",
+				__func__, __LINE__, task->pid, namefmt, name);
+
 		set_task_comm(task, name);
 		/*
 		 * root may have changed our (kthreadd's) priority or CPU mask.
-- 
2.17.1


  parent reply	other threads:[~2021-09-29 11:53 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-29 11:50 [PATCH 0/5] kthread: increase the size of kthread's comm Yafang Shao
2021-09-29 11:50 ` [PATCH 1/5] kernel: replace sizeof(task->comm) with TASK_COMM_LEN Yafang Shao
2021-09-29 18:09   ` Kees Cook
2021-09-30 12:27     ` Yafang Shao
2021-10-03  3:31   ` Al Viro
2021-10-03 14:14     ` Yafang Shao
2021-09-29 11:50 ` [PATCH 2/5] kernel/fork: allocate task->comm dynamicly Yafang Shao
2021-09-29 13:08   ` Yafang Shao
2021-09-29 18:11   ` Kees Cook
2021-09-30 12:41     ` Yafang Shao
2021-09-30 14:51       ` Petr Mladek
2021-10-01 11:58         ` Yafang Shao
2021-09-29 11:50 ` [PATCH 3/5] kernel/sched: improve the BUILD_BUG_ON() in get_task_comm() Yafang Shao
2021-09-29 18:12   ` Kees Cook
2021-09-30 12:43     ` Yafang Shao
2021-09-29 11:50 ` [PATCH 4/5] kernel: increase the size of kthread's comm Yafang Shao
2021-09-29 18:19   ` Kees Cook
2021-09-30 12:53     ` Yafang Shao
2021-09-29 11:50 ` Yafang Shao [this message]
2021-09-29 18:20   ` [PATCH 5/5] kernel/kthread: show a warning if kthread's comm is still trucated Kees Cook
2021-09-30 12:54     ` Yafang Shao
2021-09-30 15:17   ` Petr Mladek
2021-10-01 11:59     ` Yafang Shao
2021-10-03  3:41 ` [PATCH 0/5] kthread: increase the size of kthread's comm Al Viro
2021-10-03 14:20   ` Yafang Shao

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