Re: [PATCH RT] rtmutex: Flush block plug on __down_read()

[Sebastian Andrzej Siewior]

On 2019-01-04 15:33:21 [-0500], Scott Wood wrote:
> +	/*
> +	 * If sem->rtmutex blocks, the function sched_submit_work will not
> +	 * call blk_schedule_flush_plug (because tsk_is_pi_blocked would be
> +	 * true).  We must call blk_schedule_flush_plug here; if we don't
> +	 * call it, an I/O deadlock may occur.
> +	 */

I kept the original comment plus I replaced device-mapper with I/O (the
patch said already that it is not device-mapper specific and may occur
with ext4 as well).

Sebastian