linux-kernel - Re: [-next] system hangs likely due to "modules: Only return -EEXIST for modules that have finished loading"

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Date:   Sat, 27 Apr 2019 06:42:51 -0400
From:   Prarit Bhargava <prarit@...hat.com>
To:     Heiko Carstens <heiko.carstens@...ibm.com>
Cc:     Jessica Yu <jeyu@...nel.org>, linux-next@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        Cathy Avery <cavery@...hat.com>
Subject: Re: [-next] system hangs likely due to "modules: Only return -EEXIST
 for modules that have finished loading"

On 4/27/19 6:24 AM, Heiko Carstens wrote:

> 
> diff --git a/kernel/module.c b/kernel/module.c
> index 410eeb7e4f1d..48748cfec991 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -3585,6 +3585,7 @@ again:
>  					       finished_loading(mod->name));
>  			if (err)
>  				goto out_unlocked;
> +			cond_resched();
>  			goto again;
>  		}
>  		err = -EEXIST;
> 

Heiko, I'm testing on 2-cpu systems which appear to show the problem ~10% of the
time.  On another system I backed out my original patch to set a baseline, and
noticed that occasionally the time to boot the system doubles from ~4 seconds to
9 seconds.  Is this something you're also concerned with?

P.