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From: peterz@infradead.org
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
	syzbot <syzbot+c32502fd255cb3a44048@syzkaller.appspotmail.com>,
	David Miller <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	netdev <netdev@vger.kernel.org>,
	Steffen Klassert <steffen.klassert@secunet.com>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>
Subject: Re: possible deadlock in xfrm_policy_delete
Date: Thu, 24 Sep 2020 09:30:03 +0200	[thread overview]
Message-ID: <20200924073003.GZ1362448@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CACT4Y+aw+Z_7JwDiu65hL7K99f1oBfRFavZz4Pr4o8Us5peH4g@mail.gmail.com>

On Thu, Sep 24, 2020 at 06:44:12AM +0200, Dmitry Vyukov wrote:
> On Thu, Sep 24, 2020 at 6:36 AM Herbert Xu <herbert@gondor.apana.org.au> wrote:
> > >  (k-slock-AF_INET6){+.-.}-{2:2}

That's a seqlock.

> > What's going on with all these bogus lockdep reports?
> >
> > These are two completely different locks, one is for TCP and the
> > other is for SCTP.  Why is lockdep suddenly beoming confused about
> > this?
> >
> > FWIW this flood of bogus reports started on 16/Sep.
> 
> 
> FWIW one of the dups of this issue was bisected to:
> 
> commit 1909760f5fc3f123e47b4e24e0ccdc0fc8f3f106
> Author: Ahmed S. Darwish <a.darwish@linutronix.de>
> Date:   Fri Sep 4 15:32:31 2020 +0000
> 
>     seqlock: PREEMPT_RT: Do not starve seqlock_t writers
> 
> Can it be related?

Did that tree you're testing include 267580db047e ("seqlock: Unbreak
lockdep") ?

  parent reply	other threads:[~2020-09-24  7:30 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-20 20:22 possible deadlock in xfrm_policy_delete syzbot
2020-09-24  4:35 ` Herbert Xu
2020-09-24  4:44   ` Dmitry Vyukov
2020-09-24  4:48     ` Herbert Xu
2020-09-24  7:30     ` peterz [this message]
2020-09-24  7:42       ` Herbert Xu

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