linux-kernel - [PATCH] hung_task: ignore hung_task_warnings when hung_task

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Message-Id: <20240613033159.3446265-1-leonylgao@gmail.com>
Date: Thu, 13 Jun 2024 11:31:59 +0800
From: Yongliang Gao <leonylgao@...il.com>
To: kent.overstreet@...ux.dev,
	j.granados@...sung.com,
	jsiddle@...hat.com,
	akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org,
	Yongliang Gao <leonylgao@...cent.com>,
	Huang Cun <cunhuang@...cent.com>
Subject: [PATCH] hung_task: ignore hung_task_warnings when hung_task_panic is enabled

From: Yongliang Gao <leonylgao@...cent.com>

If hung_task_panic is enabled, don't consider the value of
hung_task_warnings and display the information of the hung
tasks.

In some cases, hung_task_panic might not be initially set up,
after several hung tasks occur, the hung_task_warnings count
reaches zero. If hung_task_panic is set up later, it may not
display any helpful hung task info in dmesg, only showing
messages like:

Kernel panic - not syncing: hung_task: blocked tasks
CPU: 3 PID: 58 Comm: khungtaskd Not tainted 6.10.0-rc3 #19
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
Call Trace:
 <TASK>
 panic+0x2f3/0x320
 watchdog+0x2dd/0x510
 ? __pfx_watchdog+0x10/0x10
 kthread+0xe0/0x110
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x2f/0x40
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Signed-off-by: Yongliang Gao <leonylgao@...cent.com>
Reviewed-by: Huang Cun <cunhuang@...cent.com>
---
 kernel/hung_task.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 1d92016b0b3c..6ca859715d8a 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -127,7 +127,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 	 * Ok, the task did not get scheduled for more than 2 minutes,
 	 * complain:
 	 */
-	if (sysctl_hung_task_warnings) {
+	if (sysctl_hung_task_warnings || hung_task_call_panic) {
 		if (sysctl_hung_task_warnings > 0)
 			sysctl_hung_task_warnings--;
 		pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
-- 
2.39.3