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From: Dave Hansen <dave.hansen@intel.com>
To: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: kernel test robot <ying.huang@linux.intel.com>, LKP <lkp@01.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	David Rientjes <rientjes@google.com>,
	Pekka Enberg <penberg@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
	Andi Kleen <andi@firstfloor.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Christoph Lameter <cl@linux.com>,
	Sasha Levin <sasha.levin@oracle.com>,
	Konstantin Khlebnikov <koct9i@gmail.com>,
	Yuri Gribov <tetra2005@gmail.com>,
	Andrey Konovalov <adech.fo@gmail.com>,
	Konstantin Serebryany <kcc@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [lkp] [fs] df4c0e36f1: NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1]
Date: Mon, 2 Nov 2015 12:07:36 -0800	[thread overview]
Message-ID: <5637C288.9070508@intel.com> (raw)
In-Reply-To: <CAPAsAGzpTM84NEESPt_jY0i-+W2SB37KtW1TXy93e8R2F7rEtw@mail.gmail.com>

On 11/02/2015 11:34 AM, Andrey Ryabinin wrote:
>>> >>
>>> >> [    1.159450] augmented rbtree testing -> 23675 cycles
>>> >> [    1.864996]
>>> >> It took less than a second, meanwhile in your case it didn't finish in
>>> >> 22 seconds.
>>> >>
>>> >> This makes me think that your host is overloaded and the problem is on
>>> >> your side.
>> >
>> > It's probably just a matter of putting some cond_resched()s in the test
>> > code.
> Yes, but is it worthwhile? It's very likely that lockup will just
> trigger in another place.

I'm guessing that the lockup here was because the tests were running for
too long.  If we cond_resched() in there often enough, the kernel won't
detect a softlockup at all.  It won't shift somewhere else.

  reply	other threads:[~2015-11-02 20:07 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-02  8:06 [lkp] [fs] df4c0e36f1: NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1] kernel test robot
2015-11-02  9:17 ` Dmitry Vyukov
2015-11-02  9:32 ` Andrey Ryabinin
2015-11-02 17:39   ` Dave Hansen
2015-11-02 19:34     ` Andrey Ryabinin
2015-11-02 20:07       ` Dave Hansen [this message]
2015-11-02 21:29         ` Andrey Ryabinin

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