On Mon, Sep 28, 2020 at 8:36 PM Thomas Gleixner [off-list ref] wrote:

On Tue, Sep 29 2020 at 01:11, Hillf Danton wrote:

quoted

On Mon, 28 Sep 2020 18:13:42 +0200 Thomas Gleixner wrote:

quoted

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! :)