linux-kernel - [PATCH 0/6] locking/rtmutex: Avoid PI state recursion through sched_submit

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Message-ID: <20230815110121.117752409@infradead.org>
Date:   Tue, 15 Aug 2023 13:01:21 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     bigeasy@...utronix.de, tglx@...utronix.de
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        bsegall@...gle.com, boqun.feng@...il.com, swood@...hat.com,
        bristot@...hat.com, dietmar.eggemann@....com, mingo@...hat.com,
        jstultz@...gle.com, juri.lelli@...hat.com, mgorman@...e.de,
        rostedt@...dmis.org, vschneid@...hat.com,
        vincent.guittot@...aro.org, longman@...hat.com, will@...nel.org
Subject: [PATCH 0/6] locking/rtmutex: Avoid PI state recursion through sched_submit_work()

Hi!

This is basically the 'same' patches as send earlier by Sebastian here:

  https://lkml.kernel.org/r/20230427111937.2745231-1-bigeasy@linutronix.de

I spend a number of days trying to invert rtmutex, only to make a giant mess of
things and finally conceded that this is the least horrible approach.

There's a bunch of naming differences and I added some asserts that should
hopefully avoid things from going sideways without notice. I've also updated
the changelogs to high-light the actual problem. The whole pi_blocked_on
'corruption' is a mere consequence of the more fundamental problem that the
whole PI state recurses.

I've not tested this with the rest of the RT patches stuck on, so very limited
actual testing happened.

If anybody could please confirm stuff still works as advertised, I'll go queue
this mess and we can hopefully forget all about it.