Re: [patch 00/12] hrtimers: Prevent hrtimer interrupt starvation

[Thomas Gleixner <tglx@kernel.org>]

On Tue, Apr 07 2026 at 10:54, Thomas Gleixner wrote:
> There needs to be some discussion about the scope of backporting. The first
> patch preventing the stall is obviously a backport candidate. The remaining
> series can be obviously argued about, but in my opinion it should be
> backported as well as it prevents stupid or malicious user space from
> generating tons of pointless timer interrupts.

Peter and me just discussed it over IRC. With the clockevents prevention
in place, the effect of stupid/malicious code is pretty much affecting
only the user space task itself. As the timer is forced to expire once
the clockevent device has been force armed, it won't have other side
effects as device interrupts or IPIs are not blocked out and in the
worst case marginally delayed by the high frequency timer interrupt.

Once the task is scheduled out that subsides as there is nothing which
re-arms the timer anymore.

So we should be fine with backporting the clockevents fix and leave the
other parts of the series for upstream only. I still need to investigate
how all of that affects the pending changes vs. TSC deadline timer (and
similar devices) which are not going to reach that modified clockevents
code anymore.

Thanks,

        tglx