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From:   "Liu, Chuansheng" <chuansheng.liu@intel.com>
To:     Petr Mladek <pmladek@suse.com>
CC:     Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
        "sergey.senozhatsky@gmail.com" <sergey.senozhatsky@gmail.com>,
        "rostedt@goodmis.org" <rostedt@goodmis.org>,
        "dvyukov@google.com" <dvyukov@google.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] kernel/hung_task.c: force ignore_loglevel before panic
Thread-Topic: [PATCH] kernel/hung_task.c: force ignore_loglevel before panic
Thread-Index: AdSQSf5rRH8ZTwaTR0Kl+UXxB6vgiP//fUMA//93HeCAAJABgIAAP2cA//572zCAAxdpgP/+fODAAGM4r4D//nT1YA==
Date:   Thu, 13 Dec 2018 01:53:51 +0000
Message-ID: <27240C0AC20F114CBF8149A2696CBE4A6015B695@SHSMSX101.ccr.corp.intel.com>
References: <27240C0AC20F114CBF8149A2696CBE4A6015A889@SHSMSX101.ccr.corp.intel.com>
 <20181210054622.GA6291@jagdpanzerIV>
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 <20181210061151.GA28533@jagdpanzerIV>
 <f6e39c8f-2ca2-4a01-cf42-9ed3bc2462a8@i-love.sakura.ne.jp>
 <27240C0AC20F114CBF8149A2696CBE4A6015ABB6@SHSMSX101.ccr.corp.intel.com>
 <77864d48-ce55-a699-ee6e-60d9ec36e305@i-love.sakura.ne.jp>
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 <20181212101732.5kayilcr7ww5cyu5@pathway.suse.cz>
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> -----Original Message-----
> From: Petr Mladek [mailto:pmladek@suse.com]
> Sent: Wednesday, December 12, 2018 6:18 PM
> To: Liu, Chuansheng <chuansheng.liu@intel.com>
> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>; Sergey Senozhatsky
> <sergey.senozhatsky.work@gmail.com>; akpm@linux-foundation.org;
> sergey.senozhatsky@gmail.com; rostedt@goodmis.org; dvyukov@google.com;
> linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] kernel/hung_task.c: force ignore_loglevel before panic
> 
> On Wed 2018-12-12 01:16:11, Liu, Chuansheng wrote:
> >
> >
> > > -----Original Message-----
> > > From: Tetsuo Handa [mailto:penguin-kernel@i-love.sakura.ne.jp]
> > > Sent: Tuesday, December 11, 2018 6:02 PM
> > > To: Liu, Chuansheng <chuansheng.liu@intel.com>; Sergey Senozhatsky
> > > <sergey.senozhatsky.work@gmail.com>
> > > Cc: akpm@linux-foundation.org; pmladek@suse.com;
> > > sergey.senozhatsky@gmail.com; rostedt@goodmis.org;
> dvyukov@google.com;
> > > linux-kernel@vger.kernel.org
> > > Subject: Re: [PATCH] kernel/hung_task.c: force ignore_loglevel before panic
> > >
> > > On 2018/12/11 10:16, Liu, Chuansheng wrote:
> > > > We may enhance it by:
> > > > -       if (sysctl_hung_task_warnings) {
> > > > +       if (sysctl_hung_task_panic || sysctl_hung_task_warnings) {
> > > >                 if (sysctl_hung_task_warnings > 0)
> > > >                         sysctl_hung_task_warnings--;
> > >
> > > Why ignore sysctl_hung_task_warnings? The administrator can already
> > > configure as sysctl_hung_task_warnings == -1 && sysctl_hung_task_panic
> == 1
> > > if he/she does not want to suppress neither sched_show_task() nor
> > > debug_show_all_locks()/trigger_all_cpu_backtrace(). Someone might want
> that
> > > sysctl_hung_task_warnings == 0 (which is a request to suppress only
> > > sched_show_task()) should not be ignored by sysctl_hung_task_panic == 1
> > > (which is a request to trigger panic).
> >
> >
> > My complete idea is in patch V1 which has been sent. Paste here:
> > If sysctl_hung_task_panic == 1, I will force sched_show_task(t) and set
> > hung_task_call_panic = true
> > hung_task_show_lock = true
> 
> Please, do not mix two changes into one patch.
Thanks your suggestion.

> 
> Add console_verbose() in one patch. It is simple and
> everyone has agreed with it so far.
Has sent it out, please help review.

> 
> Force sched_show_task() when hung_task_call_panic == 1 in
> another patch. It seems to be controversial and should be
> discussed/changed separately.
I found some other points also, and will send out patches later.