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From:   John Stultz <jstultz@google.com>
Date:   Mon, 6 Mar 2023 10:30:51 -0800
Message-ID: <CANDhNCqiXVQoKYYegb6gFuYn0JXPqxLUghV8g5-59RuyvKCDNw@mail.gmail.com>
Subject: Re: [PATCH] pstore: Revert pmsg_lock back to a normal mutex
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     LKML <linux-kernel@vger.kernel.org>, Wei Wang <wvw@google.com>,
        Midas Chien <midaschieh@google.com>,
        Kees Cook <keescook@chromium.org>,
        Anton Vorontsov <anton@enomsg.org>,
        "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
        Tony Luck <tony.luck@intel.com>, kernel-team@android.com,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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On Thu, Mar 2, 2023 at 5:01=E2=80=AFPM Steven Rostedt <rostedt@goodmis.org>=
 wrote:
> On Thu, 2 Mar 2023 16:56:13 -0500
> Steven Rostedt <rostedt@goodmis.org> wrote:
>
> > Knowing that rcu_read_lock() keeps the tasks safe, I made the optimizat=
ion
> > to only grab the spinlock (and disable interrupts) once, or whenever th=
e
> > 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