linux-kernel - RE: [外部邮件] Re: [PATCH][v2] hung_task: Panic after fixed number of hung tasks

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Message-ID: <6c4905288f374bf2ad48492cd03c473e@baidu.com>
Date: Sat, 11 Oct 2025 23:58:56 +0000
From: "Li,Rongqing" <lirongqing@...du.com>
To: Kees Cook <kees@...nel.org>, Randy Dunlap <rdunlap@...radead.org>,
	"corbet@....net" <corbet@....net>, "akpm@...ux-foundation.org"
	<akpm@...ux-foundation.org>, "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>, "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: [外部邮件] Re: [PATCH][v2] hung_task: Panic after fixed number of hung tasks



> 
> 
> > On October 10, 2025 5:25:05 PM PDT, Randy Dunlap
> > <rdunlap@...radead.org>
> > wrote:
> > >Hi,
> > >
> > >On 9/27/25 10:31 PM, lirongqing wrote:
> > >> From: Li RongQing <lirongqing@...du.com>
> > >>
> > >> Currently, when hung_task_panic is enabled, kernel will panic
> > >> immediately upon detecting the first hung task. However, some hung
> > >> tasks are transient and the system can recover fully, while others
> > >> are unrecoverable and trigger consecutive hung task reports, and a
> > >> panic is
> > expected.
> > >>
> > >> This commit adds a new sysctl parameter hung_task_count_to_panic to
> > >> allows specifying the number of consecutive hung tasks that must be
> > >> detected
> >
> > Why make a new sysctl? Can't you just use hung_task_panic and raise
> > the max to INT_MAX?
> >
> 

Sorry, I misunderstand at first.

I'm not sure if this sysctl hung_task_panic can be modified, and if changed, BOOTPARAM_HUNG_TASK_PANIC should be changed, and whether both changing will cause issues for users ?

If no one objects, I will reuse hung_task_panic , and not adding a new sysctl

Thanks

-Li

> 
> However, this will prevent the printing of hung task warnings. Hung task
> warnings are very useful for identifying which tasks are hanging and where
> they are stuck.
> 
> If there is this function, I hope to shorten sysctl_hung_task_timeout_secs to
> give more information.
> 
> And rcu has the similar function as dfe564045c653d "(rcu: Panic after fixed
> number of stalls)"
> 
> -Li
>