hung_task: ignore hung_task_warnings when hung_task_panic is enabled

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>

Link: https://lkml.kernel.org/r/20240613033159.3446265-1-leonylgao@gmail.com
Signed-off-by: Yongliang Gao <leonylgao@tencent.com>
Reviewed-by: Huang Cun <cunhuang@tencent.com>
Cc: Joel Granados <j.granados@samsung.com>
Cc: John Siddle <jsiddle@redhat.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 1d92016b0b3c427afff4caa91c451c81e6858722..6ca859715d8a371cc7c131f6e535dc879586d71f 100644 (file)
--- 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",