| Re: [PATCH] Check for error returned by kthread_create on creating journal thread [message #12039 is a reply to message #12033] |
Mon, 16 April 2007 10:21   |
Christoph Hellwig
Messages: 59
Registered: April 2006
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Member |
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On Mon, Apr 16, 2007 at 11:41:14AM +0400, Pavel Emelianov 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.
> --- ./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);
Note that this wait_event should exist at all, and the return
value of kthread_run should be assigned to journal->j_task. Also
the code doesn't use the kthread primitives in other places leading
to crufty code.
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