linux-kernel - Re: [PATCH v2 2/4] hung_task: Add hung_task_sys_info sysctl to dump sys info on task-hung

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Message-ID: <b8263f56-6946-4d88-b711-d5ef8937b3cb@linux.dev>
Date: Tue, 18 Nov 2025 14:06:21 +0800
From: Lance Yang <lance.yang@...ux.dev>
To: Andrew Morton <akpm@...ux-foundation.org>,
 Feng Tang <feng.tang@...ux.alibaba.com>
Cc: Petr Mladek <pmladek@...e.com>, Steven Rostedt <rostedt@...dmis.org>,
 Lance Yang <ioworker0@...il.com>, linux-kernel@...r.kernel.org,
 Jonathan Corbet <corbet@....net>, paulmck@...nel.org, lirongqing@...du.com,
 leonylgao@...cent.com
Subject: Re: [PATCH v2 2/4] hung_task: Add hung_task_sys_info sysctl to dump
 sys info on task-hung



On 2025/11/18 01:53, Andrew Morton wrote:
> On Sun, 16 Nov 2025 22:13:58 +0800 Feng Tang <feng.tang@...ux.alibaba.com> wrote:
> 
>>>>    	if (need_warning || hung_task_call_panic) {
>>>>    		si_mask |= SYS_INFO_LOCKS;
>>>
>>> Looks good to me now! I assume v3 would be expected, can you
>>> post a new version?
>>
>> Andrew has taken the patchset to -mm tree.
>>
>> Andrew, which way do you prefer? I send a v3 patch for hung-task or you
>> pickup the fixup patch and squash it into the orginal 0002 patch?
>>
>> Anyway, I make a squshed version v3 patch below.
> 
> I prefer little fixup patches, generally.  So people can see what
> changed and don't feel they should re-review everything.
> 
> I queued the below, thanks.

Thanks!

> 
> 
> From: Feng Tang <feng.tang@...ux.alibaba.com>
> Subject: hung_task-add-hung_task_sys_info-sysctl-to-dump-sys-info-on-task-hung-fix
> Date: Wed, 5 Nov 2025 19:30:36 +0800
> 
> maintain consistecy established behavior, per Lance and Petr
> 
> Link: https://lkml.kernel.org/r/aRncJo1mA5Zk77Hr@U-2FWC9VHC-2323.local
> Suggested-by: Petr Mladek <pmladek@...e.com>
> Signed-off-by: Feng Tang <feng.tang@...ux.alibaba.com>
> Cc: Jonathan Corbet <corbet@....net>
> Cc: Lance Yang <ioworker0@...il.com>
> Cc: "Paul E . McKenney" <paulmck@...nel.org>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> ---

With this fix, #02 patch looks good to me!

Reviewed-by: Lance Yang <lance.yang@...ux.dev>

> 
>   kernel/hung_task.c |   24 +++++++++++++-----------
>   1 file changed, 13 insertions(+), 11 deletions(-)
> 
> --- a/kernel/hung_task.c~hung_task-add-hung_task_sys_info-sysctl-to-dump-sys-info-on-task-hung-fix
> +++ a/kernel/hung_task.c
> @@ -223,8 +223,11 @@ static inline void debug_show_blocker(st
>   }
>   #endif
>   
> -static void check_hung_task(struct task_struct *t, unsigned long timeout)
> +static void check_hung_task(struct task_struct *t, unsigned long timeout,
> +		unsigned long prev_detect_count)
>   {
> +	unsigned long total_hung_task;
> +
>   	if (!task_is_hung(t, timeout))
>   		return;
>   
> @@ -234,13 +237,19 @@ static void check_hung_task(struct task_
>   	 */
>   	sysctl_hung_task_detect_count++;
>   
> +	total_hung_task = sysctl_hung_task_detect_count - prev_detect_count;
>   	trace_sched_process_hang(t);
>   
> +	if (sysctl_hung_task_panic && total_hung_task >= sysctl_hung_task_panic) {
> +		console_verbose();
> +		hung_task_call_panic = true;
> +	}
> +
>   	/*
>   	 * 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",
> @@ -295,7 +304,6 @@ static void check_hung_uninterruptible_t
>   {
>   	int max_count = sysctl_hung_task_check_count;
>   	unsigned long last_break = jiffies;
> -	unsigned long total_hung_task;
>   	struct task_struct *g, *t;
>   	unsigned long prev_detect_count = sysctl_hung_task_detect_count;
>   	int need_warning = sysctl_hung_task_warnings;
> @@ -320,20 +328,14 @@ static void check_hung_uninterruptible_t
>   			last_break = jiffies;
>   		}
>   
> -		check_hung_task(t, timeout);
> +		check_hung_task(t, timeout, prev_detect_count);
>   	}
>    unlock:
>   	rcu_read_unlock();
>   
> -	total_hung_task = sysctl_hung_task_detect_count - prev_detect_count;
> -	if (!total_hung_task)
> +	if (!(sysctl_hung_task_detect_count - prev_detect_count))
>   		return;
>   
> -	if (sysctl_hung_task_panic && total_hung_task >= sysctl_hung_task_panic) {
> -		console_verbose();
> -		hung_task_call_panic = true;
> -	}
> -
>   	if (need_warning || hung_task_call_panic) {
>   		si_mask |= SYS_INFO_LOCKS;
>   
> _
>