Re: [PATCH 1/2] sched/wait: Break up long wake list walk

[Peter Zijlstra <peterz@infradead.org>]

On Tue, Aug 22, 2017 at 11:19:12AM -0700, Linus Torvalds wrote:
> diff --git a/mm/filemap.c b/mm/filemap.c
> index a49702445ce0..75c29a1f90fb 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -991,13 +991,11 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
>  			}
>  		}
>  
> -		if (lock) {
> -			if (!test_and_set_bit_lock(bit_nr, &page->flags))
> -				break;
> -		} else {
> -			if (!test_bit(bit_nr, &page->flags))
> -				break;
> -		}
> +		if (!lock)
> +			break;
> +
> +		if (!test_and_set_bit_lock(bit_nr, &page->flags))
> +			break;
>  	}

Won't we now prematurely terminate the wait when we get a spurious
wakeup?

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