Re: [PATCH 1/5] page allocator: Always wake kswapd when restartingan allocation attempt after direct reclaim failed

[David Rientjes]

On Mon, 26 Oct 2009, KOSAKI Motohiro wrote:

> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index bf72055..5a27896 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1899,6 +1899,12 @@ rebalance:
>  	if (should_alloc_retry(gfp_mask, order, pages_reclaimed)) {
>  		/* Wait for some write requests to complete then retry */
>  		congestion_wait(BLK_RW_ASYNC, HZ/50);
> +
> +		/*
> +		 * While we wait congestion wait, Amount of free memory can
> +		 * be changed dramatically. Thus, we kick kswapd again.
> +		 */
> +		wake_all_kswapd(order, zonelist, high_zoneidx);
>  		goto rebalance;
>  	}
>  

We're blocking to finish writeback of the directly reclaimed memory, why 
do we need to wake kswapd afterwards?
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