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From: Thomas Gleixner <tglx@linutronix.de>
To: paulmck@kernel.org
Cc: syzbot <syzbot+3ae5eaae0809ee311e75@syzkaller.appspotmail.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	bp@alien8.de, hpa@zytor.com, linux-kernel@vger.kernel.org,
	luto@kernel.org, mingo@kernel.org,
	syzkaller-bugs@googlegroups.com, x86@kernel.org
Subject: Re: WARNING: suspicious RCU usage in idtentry_exit
Date: Thu, 28 May 2020 22:19:02 +0200	[thread overview]
Message-ID: <878shbols9.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20200528161143.GF2869@paulmck-ThinkPad-P72>

Paul,

"Paul E. McKenney" <paulmck@kernel.org> writes:
> On Thu, May 28, 2020 at 03:33:44PM +0200, Thomas Gleixner wrote:
>> syzbot <syzbot+3ae5eaae0809ee311e75@syzkaller.appspotmail.com> writes:
>> Weird. I have no idea how that thing is an EQS here.
>
> No argument on the "Weird" part!  ;-)
>
> Is this a NO_HZ_FULL=y kernel?

No, it has only NO_HZ_IDLE.

  https://syzkaller.appspot.com/x/.config?x=47b0740d89299c10

> If so, one possibility is that the call
> to rcu_user_exit() went missing somehow.  If not, then RCU should have
> been watching userspace execution.
>
> Again, the only thing I can think of (should this prove to be
> reproducible) is the rcu_dyntick trace event.

:)

Thanks,

        tglx

  reply	other threads:[~2020-05-28 20:19 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-26  3:54 WARNING: suspicious RCU usage in idtentry_exit syzbot
2020-05-28 13:33 ` Thomas Gleixner
2020-05-28 16:11   ` Paul E. McKenney
2020-05-28 20:19     ` Thomas Gleixner [this message]
2020-05-28 20:48       ` Paul E. McKenney
2020-05-29  6:20         ` Dmitry Vyukov
2020-05-29  8:51           ` Thomas Gleixner
2020-05-29 14:05           ` Paul E. McKenney
2020-05-29 14:32             ` Dmitry Vyukov
2020-05-29 16:07               ` Paul E. McKenney
2020-07-31  9:23   ` [tip: core/rcu] lockdep: Complain only once about RCU in extended quiescent state tip-bot2 for Paul E. McKenney

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