linux-kernel - Re: [RFC PATCH 07/11] sched: Add proxy execution

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Date:   Sun, 16 Oct 2022 16:48:09 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Joel Fernandes <joel@...lfernandes.org>,
        Connor O'Brien <connoro@...gle.com>,
        linux-kernel@...r.kernel.org, kernel-team@...roid.com,
        John Stultz <jstultz@...gle.com>,
        Qais Yousef <qais.yousef@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Valentin Schneider <vschneid@...hat.com>,
        Will Deacon <will@...nel.org>,
        Waiman Long <longman@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        "Paul E . McKenney" <paulmck@...nel.org>, youssefesmat@...gle.com
Subject: Re: [RFC PATCH 07/11] sched: Add proxy execution

On Sat, 15 Oct 2022 15:53:19 +0200
Peter Zijlstra <peterz@...radead.org> wrote:

> >From this it is easy to see that the critical secion executes with the  
> direct sum of the blockchain as a whole (all of them will have donated
> their relative time to make the owner elegible again) -- provided the
> critical section is of course long enough for this to matter (or it's
> owner's weight small enough etc..).

Does this mean that a lower priority task could do a sort of DOS attack
on a high priority task, if it creates a bunch of threads that
constantly grabs a shared lock from the higher priority task? That is,
the higher priority task could possibly lose a lot of its quota due to
other tasks running on its behalf in the critical section?

-- Steve