linux-kernel - RE: [????] Re: [PATCH][RFC] hung_task: Support to panic when the maximum number of hung task warnings is reached

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Message-ID: <f11f4dd1983f4073a8008112e55f92f8@baidu.com>
Date: Tue, 23 Sep 2025 04:00:03 +0000
From: "Li,Rongqing" <lirongqing@...du.com>
To: Andrew Morton <akpm@...ux-foundation.org>
CC: "corbet@....net" <corbet@....net>, "lance.yang@...ux.dev"
	<lance.yang@...ux.dev>, "mhiramat@...nel.org" <mhiramat@...nel.org>,
	"paulmck@...nel.org" <paulmck@...nel.org>,
	"pawan.kumar.gupta@...ux.intel.com" <pawan.kumar.gupta@...ux.intel.com>,
	"mingo@...nel.org" <mingo@...nel.org>, "dave.hansen@...ux.intel.com"
	<dave.hansen@...ux.intel.com>, "rostedt@...dmis.org" <rostedt@...dmis.org>,
	"kees@...nel.org" <kees@...nel.org>, "arnd@...db.de" <arnd@...db.de>,
	"feng.tang@...ux.alibaba.com" <feng.tang@...ux.alibaba.com>,
	"pauld@...hat.com" <pauld@...hat.com>, "joel.granados@...nel.org"
	<joel.granados@...nel.org>, "linux-doc@...r.kernel.org"
	<linux-doc@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [????] Re: [PATCH][RFC] hung_task: Support to panic when the
 maximum number of hung task warnings is reached



> -----Original Message-----
> From: Andrew Morton <akpm@...ux-foundation.org>
> Sent: 2025年9月23日 11:46
> To: Li,Rongqing <lirongqing@...du.com>
> Cc: corbet@....net; lance.yang@...ux.dev; mhiramat@...nel.org;
> paulmck@...nel.org; pawan.kumar.gupta@...ux.intel.com; mingo@...nel.org;
> dave.hansen@...ux.intel.com; rostedt@...dmis.org; kees@...nel.org;
> arnd@...db.de; feng.tang@...ux.alibaba.com; pauld@...hat.com;
> joel.granados@...nel.org; linux-doc@...r.kernel.org;
> linux-kernel@...r.kernel.org
> Subject: [????] Re: [PATCH][RFC] hung_task: Support to panic when the
> maximum number of hung task warnings is reached
> 
> On Tue, 23 Sep 2025 11:37:40 +0800 lirongqing <lirongqing@...du.com> wrote:
> 
> > Currently the hung task detector can either panic immediately or
> > continue operation when hung tasks are detected. However, there are
> > scenarios where we want a more balanced approach:
> >
> > - We don't want the system to panic immediately when a few hung tasks
> >   are detected, as the system may be able to recover
> > - And we also don't want the system to stall indefinitely with multiple
> >   hung tasks
> >
> > This commit introduces a new mode (value 2) for the hung task panic behavior.
> > When set to 2, the system will panic only after the maximum number of
> > hung task warnings (hung_task_warnings) has been reached.
> >
> > This provides a middle ground between immediate panic and potentially
> > infinite stall, allowing for automated vmcore generation after a
> > reasonable
> 
> I assume the same argument applies to the NMI watchdog, to the softlockup
> detector and to the RCU stall detector?

True, especial RCU stall detector

> 
> A general framework to handle all of these might be better.  But why do it in
> kernel at all?  What about a userspace detector which parses kernel logs (or
> new procfs counters) and makes such decisions?


By leveraging existing kernel mechanisms, implementation in kernel is very simple and reliable, I think

Thanks

-Li