linux-kernel - Re: [PATCH 5.4] sched/rt: Disable RT_RUNTIME

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <YtF2KVJkAnUlx5li@kroah.com>
Date:   Fri, 15 Jul 2022 16:14:01 +0200
From:   Greg KH <greg@...ah.com>
To:     Mark-PK Tsai <mark-pk.tsai@...iatek.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Matthias Brugger <matthias.bgg@...il.com>,
        yj.chiang@...iatek.com,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        stable@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 5.4] sched/rt: Disable RT_RUNTIME_SHARE by default

On Thu, Jul 14, 2022 at 03:30:52PM +0800, Mark-PK Tsai wrote:
> From: Daniel Bristot de Oliveira <bristot@...hat.com>
> 
> commit 2586af1ac187f6b3a50930a4e33497074e81762d upstream.
> 
> The RT_RUNTIME_SHARE sched feature enables the sharing of rt_runtime
> between CPUs, allowing a CPU to run a real-time task up to 100% of the
> time while leaving more space for non-real-time tasks to run on the CPU
> that lend rt_runtime.
> 
> The problem is that a CPU can easily borrow enough rt_runtime to allow
> a spinning rt-task to run forever, starving per-cpu tasks like kworkers,
> which are non-real-time by design.
> 
> This patch disables RT_RUNTIME_SHARE by default, avoiding this problem.
> The feature will still be present for users that want to enable it,
> though.
> 
> Signed-off-by: Daniel Bristot de Oliveira <bristot@...hat.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Tested-by: Wei Wang <wvw@...gle.com>
> Link: https://lkml.kernel.org/r/b776ab46817e3db5d8ef79175fa0d71073c051c7.1600697903.git.bristot@redhat.com
> Signed-off-by: Mark-PK Tsai <mark-pk.tsai@...iatek.com>
> Cc: stable@...r.kernel.org
> ---
>  kernel/sched/features.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Now queued up, thanks.

greg k-h