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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Linux-RT <linux-rt-users@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] locking/rwbase: Prevent indefinite writer starvation
Date: Fri, 20 Jan 2023 14:38:27 +0100	[thread overview]
Message-ID: <Y8qZU33Cvbc7p7DE@linutronix.de> (raw)
In-Reply-To: <20230120132441.4jjke47rnpikiuf5@techsingularity.net>

On 2023-01-20 13:24:41 [+0000], Mel Gorman wrote:
> --- a/kernel/locking/rwbase_rt.c
> +++ b/kernel/locking/rwbase_rt.c
> @@ -264,12 +291,17 @@ static int __sched rwbase_write_lock(struct rwbase_rt *rwb,
>  		if (__rwbase_write_trylock(rwb))
>  			break;
>  
> +		/* Record timeout when reader bias is ignored. */
> +		rwb->waiter_timeout = jiffies + RWBASE_RT_WAIT_TIMEOUT;
		rwb->waiter_timeout = (jiffies + RWBASE_RT_WAIT_TIMEOUT) | 1;

There is the unlikely case that (jiffies + RWBASE_RT_WAIT_TIMEOUT) = 0
on 32bit where it is not jiffies64.

Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

> +
>  		raw_spin_unlock_irqrestore(&rtm->wait_lock, flags);
>  		rwbase_schedule();
>  		raw_spin_lock_irqsave(&rtm->wait_lock, flags);
>  
>  		set_current_state(state);
>  	}
> +
> +	rwb->waiter_timeout = 0;
>  	rwbase_restore_current_state();
>  	trace_contention_end(rwb, 0);

Sebastian

  reply	other threads:[~2023-01-20 13:38 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-17  8:38 [PATCH v2] locking/rwbase: Prevent indefinite writer starvation Mel Gorman
     [not found] ` <20230117105031.2512-1-hdanton@sina.com>
2023-01-17 12:18   ` Mel Gorman
2023-01-17 14:22 ` Sebastian Andrzej Siewior
2023-01-17 16:50   ` Mel Gorman
2023-01-18 10:45     ` Ingo Molnar
2023-01-18 16:00       ` Mel Gorman
2023-01-18 15:25     ` Sebastian Andrzej Siewior
2023-01-18 17:31       ` Mel Gorman
2023-01-19  8:25         ` Sebastian Andrzej Siewior
2023-01-19 11:02           ` Mel Gorman
2023-01-19 16:28             ` Sebastian Andrzej Siewior
2023-01-19 17:41               ` Mel Gorman
2023-01-19 17:48                 ` Davidlohr Bueso
2023-01-19 17:58                   ` Davidlohr Bueso
2023-01-20  8:25                 ` Sebastian Andrzej Siewior
2023-01-20 13:24                   ` Mel Gorman
2023-01-20 13:38                     ` Sebastian Andrzej Siewior [this message]
2023-01-20 14:07                       ` Mel Gorman
2023-01-20 15:36                     ` Davidlohr Bueso

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