linux-kernel - Re: [sched_ext/for-6.11]: Issue with BPF Scheduler during CPU Hotplug

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Message-ID: <ZszKI2GA-8yparh_@slm.duckdns.org>
Date: Mon, 26 Aug 2024 08:32:03 -1000
From: Tejun Heo <tj@...nel.org>
To: Aboorva Devarajan <aboorvad@...ux.ibm.com>
Cc: void@...ifault.com, linux-kernel@...r.kernel.org
Subject: Re: [sched_ext/for-6.11]: Issue with BPF Scheduler during CPU Hotplug

Hello,

On Fri, Aug 23, 2024 at 02:50:01PM +0530, Aboorva Devarajan wrote:
...
> I applied this patch to the almost latest sched-ext (for-6.12) branch upto
> commit 89909296a51e792 ("sched_ext: Don't use double locking to migrate
> tasks across CPUs") and let the test run for over 20 hours, and it completed
> without any hangs on both x86 and PowerPC.
> 
> So, indeed, making sure that both scx_fork_rwsem and cpu_hotplug_lock (read)
> are only held together simulataneously when they can both be acquired seems
> to be resolving the deadlock.

Thanks a lot for confirming. Let me think it over a bit re. what should be
applied.

Thanks.

-- 
tejun