On Wed 30-03-16 09:07:52, Jens Axboe wrote:
> Note in the bdi_writeback structure if a task is currently being
> limited in balance_dirty_pages(), waiting for writeback to
> proceed.
...
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 11ff8f758631..15e696bc5d14 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -1746,7 +1746,9 @@ pause:
> pause,
> start_time);
> __set_current_state(TASK_KILLABLE);
> + wb->dirty_sleeping = 1;
> io_schedule_timeout(pause);
> + wb->dirty_sleeping = 0;
Huh, but wb->dirty_sleeping is shared by all the processes in the system.
So this is seriously racy, isn't it? You rather need a counter for this to
work.
Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR
