From: Dmitry Vyukov <dvyukov@google.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Hillf Danton <hdanton@sina.com>,
syzbot <syzbot+ca740b95a16399ceb9a5@syzkaller.appspotmail.com>,
David Miller <davem@davemloft.net>,
hchunhui@mail.ustc.edu.cn, Julian Anastasov <ja@ssi.bg>,
James Morris <jmorris@namei.org>,
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
LKML <linux-kernel@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
Johannes Berg <johannes.berg@intel.com>
Subject: Re: WARNING in hrtimer_forward
Date: Wed, 30 Sep 2020 09:26:59 +0200 [thread overview]
Message-ID: <CACT4Y+YMTiR5bKKEV2vfSfrqSjoGjjsfWfhreBsNdxQ+yDpS2g@mail.gmail.com> (raw)
In-Reply-To: <87mu19kaup.fsf@nanos.tec.linutronix.de>
On Mon, Sep 28, 2020 at 8:36 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> On Tue, Sep 29 2020 at 01:11, Hillf Danton wrote:
> > On Mon, 28 Sep 2020 18:13:42 +0200 Thomas Gleixner wrote:
> >> So the timer was armed at some point and then the expiry which does the
> >> forward races with the ioctl which starts the timer. Lack of
> >> serialization or such ...
> >
> > To make syzbot happy, s/hrtimer_is_queued/hrtimer_active/ can close
> > that race but this warning looks benign.
>
> Why only make sysbot happy? It's clearly an issue and the warning is not
> benign simply because forwarding a queued timer is an absolute NONO.
> timers (both timer_list and hrtimer) need external synchronization.
Oh, Thomas, it's so nice to hear this interpretation of things among
all the cases where people only fixing tools and making them happy :)
Don't make my tools happy! They don't need that! :)
next prev parent reply other threads:[~2020-09-30 7:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-25 8:48 WARNING in hrtimer_forward syzbot
2020-09-27 0:38 ` syzbot
2020-09-27 14:29 ` syzbot
2020-09-28 16:13 ` Thomas Gleixner
[not found] ` <20200928171137.16804-1-hdanton@sina.com>
2020-09-28 18:35 ` Thomas Gleixner
2020-09-30 7:26 ` Dmitry Vyukov [this message]
[not found] ` <20200927080452.18340-1-hdanton@sina.com>
2020-09-28 14:18 ` Thomas Gleixner
2021-11-03 9:21 ` [syzbot] " syzbot
2021-12-04 10:19 ` Dmitry Vyukov
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