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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: dvyukov@google.com, peterz@infradead.org
Cc: mingo@kernel.org, akpm@linux-foundation.org,
	paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
	torvalds@linux-foundation.org, msb@chromium.org,
	tglx@linutronix.de, vegard.nossum@oracle.com
Subject: Re: [PATCH v2] locking/hung_task: Show all hung tasks before panic
Date: Sun, 8 Apr 2018 01:24:24 +0900	[thread overview]
Message-ID: <201804080124.GHG87587.SVFOOQFLOHMJtF@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <CACT4Y+Z6_P9mj2TEE3mtCez1je7dbviftM0rPcgsmQ-yFYYmBg@mail.gmail.com>

Dmitry Vyukov wrote:
> On Sat, Apr 7, 2018 at 5:39 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> > On Sat, Apr 07, 2018 at 09:31:19PM +0900, Tetsuo Handa wrote:
> >> are for replacing debug_show_all_locks() in check_hung_task() for cases like
> >> https://syzkaller.appspot.com/bug?id=26aa22915f5e3b7ca2cfca76a939f12c25d624db
> >> because we are interested in only threads holding locks.
> >>
> >> SysRq-t is too much but SysRq-w is useless for killable/interruptible threads...
> >
> > Or use a script to process the sysrq-t output? I mean, we can add all
> > sorts, but where does it end?

Maybe allow khungtaskd to call call_usermode_helper() to run arbitrary operations
instead of just calling panic()?

> 
> Good question.
> We are talking about few dozen more stacks, right?
> 
> Not all kernel bugs are well reproducible, so it's not always possible
> to go back and hit sysrq-t. And this come up in the context of syzbot,
> which is an automated system. It reported a bunch of hangs and most of
> them are real bugs, but not all of them are easily actionable.
> Can it be a config or a command line argument, which will make syzbot
> capture more useful context for each such hang?
> 

It will be nice if syzbot testing is done with kdump configured, and the
result of automated scripting on vmcore (such as "foreach bt -s -l") is
available.

  reply	other threads:[~2018-04-07 16:24 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-02 14:12 [PATCH] locking/hung_task: Show all hung tasks before panic Tetsuo Handa
2018-04-02 15:35 ` Paul E. McKenney
2018-04-02 21:09   ` Tetsuo Handa
2018-04-03 15:23   ` Dmitry Vyukov
2018-04-04 22:05     ` [PATCH v2] " Tetsuo Handa
2018-04-07 12:31       ` Tetsuo Handa
2018-04-07 15:39         ` Peter Zijlstra
2018-04-07 16:03           ` Dmitry Vyukov
2018-04-07 16:24             ` Tetsuo Handa [this message]
2018-04-09  9:03               ` Dmitry Vyukov
2018-04-09 11:13                 ` Tetsuo Handa
2018-04-09 11:50                   ` Dmitry Vyukov

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