From: Greg KH <gregkh@linuxfoundation.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: frederic@kernel.org, paulmck@kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH 4.19] hrtimer: Report offline hrtimer enqueue
Date: Tue, 13 Feb 2024 17:18:51 +0100 [thread overview]
Message-ID: <2024021344-reveal-flying-3752@gregkh> (raw)
In-Reply-To: <87h6icgz7o.ffs@tglx>
On Tue, Feb 13, 2024 at 04:28:59PM +0100, Thomas Gleixner wrote:
>
> From: Frederic Weisbecker <frederic@kernel.org>
>
> commit dad6a09f3148257ac1773cd90934d721d68ab595 upstream.
>
> The hrtimers migration on CPU-down hotplug process has been moved
> earlier, before the CPU actually goes to die. This leaves a small window
> of opportunity to queue an hrtimer in a blind spot, leaving it ignored.
>
> For example a practical case has been reported with RCU waking up a
> SCHED_FIFO task right before the CPUHP_AP_IDLE_DEAD stage, queuing that
> way a sched/rt timer to the local offline CPU.
>
> Make sure such situations never go unnoticed and warn when that happens.
>
> Fixes: 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier")
> Reported-by: Paul E. McKenney <paulmck@kernel.org>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: stable@vger.kernel.org
> Link: https://lore.kernel.org/r/20240129235646.3171983-4-boqun.feng@gmail.com
> ---
>
> Backport to 4.19 as tglx has too much spare time...
Now queued up, thanks.
greg k-h
prev parent reply other threads:[~2024-02-13 16:19 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-13 13:00 FAILED: patch "[PATCH] hrtimer: Report offline hrtimer enqueue" failed to apply to 4.19-stable tree gregkh
2024-02-13 15:28 ` [PATCH 4.19] hrtimer: Report offline hrtimer enqueue Thomas Gleixner
2024-02-13 16:18 ` Greg KH [this message]
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