From: Thomas Gleixner <tglx@linutronix.de>
To: Mike Galbraith <efault@gmx.de>,
Gratian Crisan <gratian.crisan@ni.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org,
Brandon Streiff <brandon.streiff@ni.com>,
Ingo Molnar <mingo@redhat.com>,
Darren Hart <dvhart@infradead.org>,
James Minor <james.minor@ni.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: BUG_ON(!newowner) in fixup_pi_state_owner()
Date: Wed, 04 Nov 2020 11:24:52 +0100 [thread overview]
Message-ID: <874km5mnbf.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <5f536491708682fc3b86cb5b7bc1e05ffa3521e7.camel@gmx.de>
On Wed, Nov 04 2020 at 08:42, Mike Galbraith wrote:
> On Wed, 2020-11-04 at 01:56 +0100, Mike Galbraith wrote:
> --- a/kernel/futex.c
> +++ b/kernel/futex.c
> @@ -2383,7 +2383,18 @@ static int fixup_pi_state_owner(u32 __us
> * Since we just failed the trylock; there must be an owner.
> */
> newowner = rt_mutex_owner(&pi_state->pi_mutex);
> - BUG_ON(!newowner);
> +
> + /*
> + * Why? Because I know what I'm doing with these beasts? Nope,
> + * but what the hell, a busy restart loop let f_boosted become
> + * owner, so go for it. Box still boots, works, no longer makes
> + * boom with fbomb_v2, and as an added bonus, didn't even blow
> + * futextests all up. Maybe it'll help... or not, we'll see.
> + */
> + if (unlikely(!newowner)) {
> + err = -EAGAIN;
> + goto handle_err;
Yes, that cures it, but does not really explain why newowner is
NULL. Lemme stare more.
next prev parent reply other threads:[~2020-11-04 10:26 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-28 23:24 BUG_ON(!newowner) in fixup_pi_state_owner() Gratian Crisan
2020-11-03 23:31 ` Gratian Crisan
2020-11-04 0:56 ` Mike Galbraith
2020-11-04 7:42 ` Mike Galbraith
2020-11-04 10:24 ` Thomas Gleixner [this message]
2020-11-04 11:17 ` Thomas Gleixner
2020-11-04 13:26 ` Thomas Gleixner
2020-11-04 13:43 ` Mike Galbraith
2020-11-04 15:12 ` [PATCH] futex: Handle transient "ownerless" rtmutex state correctly Thomas Gleixner
2020-11-04 15:22 ` Thomas Gleixner
2020-11-04 16:50 ` Mike Galbraith
2020-11-05 6:32 ` Gratian Crisan
2020-11-04 10:00 ` BUG_ON(!newowner) in fixup_pi_state_owner() Thomas Gleixner
2020-11-06 21:26 ` [tip: locking/urgent] futex: Handle transient "ownerless" rtmutex state correctly tip-bot2 for Mike Galbraith
2020-11-07 17:05 ` Mike Galbraith
2020-11-07 21:07 ` Thomas Gleixner
2020-11-07 21:08 ` tip-bot2 for Mike Galbraith
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