linux-kernel - Re: [PATCH] pstore: Revert pmsg

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Date:   Mon, 6 Mar 2023 10:30:51 -0800
From:   John Stultz <jstultz@...gle.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     LKML <linux-kernel@...r.kernel.org>, Wei Wang <wvw@...gle.com>,
        Midas Chien <midaschieh@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Anton Vorontsov <anton@...msg.org>,
        "Guilherme G. Piccoli" <gpiccoli@...lia.com>,
        Tony Luck <tony.luck@...el.com>, kernel-team@...roid.com,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: Re: [PATCH] pstore: Revert pmsg_lock back to a normal mutex

On Thu, Mar 2, 2023 at 5:01 PM Steven Rostedt <rostedt@...dmis.org> wrote:
> On Thu, 2 Mar 2023 16:56:13 -0500
> Steven Rostedt <rostedt@...dmis.org> wrote:
>
> > Knowing that rcu_read_lock() keeps the tasks safe, I made the optimization
> > to only grab the spinlock (and disable interrupts) once, or whenever the
> > top waiter changes.
>
> v3 as I found that there were too places to test for top waiter that had to
> be removed:

Hey Steven,
  Unfortunately previous versions didn't improve the situation for the
reporter, and this version is causing crashes (BUG at
kernel/locking/rtmutex_common.h:118!) for them.

I'm going to spend some time today to get a local reproducer so I can
tinker a bit here as well.

thanks
-john