Re: wait_on_page_bit_common(TASK_KILLABLE, EXCLUSIVE) can miss wakeup?

[Oleg Nesterov]

On 06/27, Linus Torvalds wrote:
>
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1150,6 +1150,12 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
>  			io_schedule();
>  
>  		if (behavior == EXCLUSIVE) {
> +			/*
> +			 * Make sure we don't get any exclusive wakeups
> +			 * after this point!
> +			 */
> +			__set_current_state(TASK_RUNNING);
> +			smp_mb__before_atomic();
>  			if (!test_and_set_bit_lock(bit_nr, &page->flags))
>  				break;
>  		} else if (behavior == SHARED) {

FWIW,

Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx>