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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
	John Ogness <john.ogness@linutronix.de>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <senozhatsky@chromium.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"open list:ARM/Amlogic Meson..."
	<linux-amlogic@lists.infradead.org>,
	Theodore Ts'o <tytso@mit.edu>,
	Alexander Potapenko <glider@google.com>,
	Marco Elver <elver@google.com>,
	kasan-dev@googlegroups.com
Subject: Re: [PATCH printk v5 1/1] printk: extend console_lock for per-console locking
Date: Fri, 17 Jun 2022 18:51:48 +0200	[thread overview]
Message-ID: <YqyxJJ8Jrr4zEPmM@linutronix.de> (raw)
In-Reply-To: <YqHnH+Yc4TCOXa9X@zx2c4.com>

On 2022-06-09 14:27:11 [+0200], Jason A. Donenfeld wrote:
> Hi Dmitry,
> 
> On Thu, Jun 09, 2022 at 02:18:19PM +0200, Dmitry Vyukov wrote:
> > > AFAIK, CONFIG_PROVE_RAW_LOCK_NESTING is useful for teasing out cases
> > > where RT's raw spinlocks will nest wrong with RT's sleeping spinlocks.
> > > But nobody who wants an RT kernel will be using KFENCE. So this seems
> > > like a non-issue? Maybe just add a `depends on !KFENCE` to
> > > PROVE_RAW_LOCK_NESTING?
> > 
> > Don't know if there are other good solutions (of similar simplicity).
> 
> Fortunately, I found one that solves things without needing to
> compromise on anything:
> https://lore.kernel.org/lkml/20220609121709.12939-1-Jason@zx2c4.com/
> 
> > Btw, should this new CONFIG_PROVE_RAW_LOCK_NESTING be generally
> > enabled on testing systems? We don't have it enabled on syzbot.
> 
> Last time I spoke with RT people about this, the goal was eventually to
> *always* enable it when lock proving is enabled, but there are too many
> bugs and cases now to do that, so it's an opt-in. I might be
> misremembering, though, so CC'ing Sebastian in case he wants to chime
> in.

That is basically still the case. If CONFIG_PROVE_RAW_LOCK_NESTING yells
then there will be yelling on PREEMPT_RT, too. We would like to get
things fixed ;)

Without going through this thread, John is looking at printk and printk
triggers a few of those. That is one of reasons why this is not enabled
by default.

> Jason

Sebastian

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  parent reply	other threads:[~2022-06-17 16:52 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20220421212250.565456-1-john.ogness@linutronix.de>
     [not found] ` <20220421212250.565456-15-john.ogness@linutronix.de>
     [not found]   ` <878rrs6ft7.fsf@jogness.linutronix.de>
     [not found]     ` <Ymfgis0EAw0Oxoa5@alley>
     [not found]       ` <Ymfwk+X0CHq6ex3s@alley>
     [not found]         ` <CGME20220427070833eucas1p27a32ce7c41c0da26f05bd52155f0031c@eucas1p2.samsung.com>
2022-04-27  7:08           ` [PATCH printk v5 1/1] printk: extend console_lock for per-console locking Marek Szyprowski
2022-04-27  7:38             ` Petr Mladek
2022-04-27 11:44               ` Marek Szyprowski
2022-04-27 16:15                 ` John Ogness
2022-04-27 16:48                   ` Petr Mladek
2022-04-28 14:54                   ` Petr Mladek
2022-04-29 13:53                   ` Marek Szyprowski
2022-04-30 16:00                     ` John Ogness
2022-05-02  9:19                       ` Marek Szyprowski
2022-05-02 13:11                         ` John Ogness
2022-05-02 22:29                           ` Marek Szyprowski
2022-05-04  5:56                             ` John Ogness
2022-05-04  6:52                               ` Marek Szyprowski
2022-06-08 15:10                           ` Geert Uytterhoeven
2022-06-09 11:19                             ` John Ogness
2022-06-09 11:58                               ` Jason A. Donenfeld
2022-06-09 12:18                                 ` Dmitry Vyukov
2022-06-09 12:27                                   ` Jason A. Donenfeld
2022-06-09 12:32                                     ` Dmitry Vyukov
2022-06-17 16:51                                     ` Sebastian Andrzej Siewior [this message]
2022-06-09 12:18                                 ` Jason A. Donenfeld
2022-05-02 13:17                         ` Petr Mladek
2022-05-02 23:13                           ` Marek Szyprowski
2022-05-03  6:49                             ` Petr Mladek
2022-05-04  6:05                               ` Marek Szyprowski
2022-05-04 21:11                             ` John Ogness
2022-05-04 22:42                               ` John Ogness
2022-05-05 22:33                                 ` John Ogness
2022-05-06  6:43                                   ` Marek Szyprowski
2022-05-06  7:55                                     ` Neil Armstrong
2022-05-08 11:02                                       ` John Ogness
2022-05-06  8:16                                     ` Petr Mladek
2022-05-06  9:20                                     ` John Ogness

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