[Devel] Re: [PATCH] Check for error returned by kthread_create on creating journal thread

[Andrew Morton]

On Mon, 16 Apr 2007 11:41:14 +0400
Pavel Emelianov <xemul at sw.ru> wrote:

> If the thread failed to create the subsequent wait_event
> will hang forever.
> 
> This is likely to happen if kernel hits max_threads limit.
> 
> Will be critical for virtualization systems that limit the
> number of tasks and kernel memory usage within the container.
> 
> 
> [diff-jbd-check-start-journal-thread-return-value  text/plain (1.7KB)]
> --- ./fs/jbd/journal.c.jbdthreads	2007-04-16 11:17:36.000000000 +0400
> +++ ./fs/jbd/journal.c	2007-04-16 11:30:09.000000000 +0400
> @@ -211,10 +211,16 @@ end_loop:
>  	return 0;
>  }
>  
> -static void journal_start_thread(journal_t *journal)
> +static int journal_start_thread(journal_t *journal)
>  {
> -	kthread_run(kjournald, journal, "kjournald");
> +	struct task_struct *t;
> +
> +	t = kthread_run(kjournald, journal, "kjournald");
> +	if (IS_ERR(t))
> +		return PTR_ERR(t);
> +
>  	wait_event(journal->j_wait_done_commit, journal->j_task != 0);
> +	return 0;
>  }

Thanks.   Please don't forget those Signed-off-by:s

I assume that you runtime tested this and that the mount failed in
an appropriate fashion?