Re: [PATCH] do_migrate_range: avoid failure as much as possible

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Mon, 25 Oct 2010 10:47:31 +0800
Bob Liu <lliubbo@gmail.com> wrote:

> It's normal for isolate_lru_page() to fail at times. The failures are
> typically temporal and may well go away when offline_pages() retries
> the call. So it seems more reasonable to migrate as much as possible
> to increase the chance of complete success in next retry.
> 
> This patch remove page_count() check and remove putback_lru_pages() and
> call migrate_pages() regardless of not_managed to reduce failure as much
> as possible.
> 
> Signed-off-by: Bob Liu <lliubbo@gmail.com>

-EBUSY should be returned.

-Kame


> ---
>  mm/memory_hotplug.c |   12 ------------
>  1 files changed, 0 insertions(+), 12 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index a4cfcdc..b64cc9b 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -687,7 +687,6 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
>  	unsigned long pfn;
>  	struct page *page;
>  	int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
> -	int not_managed = 0;
>  	int ret = 0;
>  	LIST_HEAD(source);
>  
> @@ -709,10 +708,6 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
>  					    page_is_file_cache(page));
>  
>  		} else {
> -			/* Becasue we don't have big zone->lock. we should
> -			   check this again here. */
> -			if (page_count(page))
> -				not_managed++;
>  #ifdef CONFIG_DEBUG_VM
>  			printk(KERN_ALERT "removing pfn %lx from LRU failed\n",
>  			       pfn);
> @@ -720,13 +715,6 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
>  #endif
>  		}
>  	}
> -	ret = -EBUSY;
> -	if (not_managed) {
> -		if (!list_empty(&source))
> -			putback_lru_pages(&source);
> -		goto out;
> -	}
> -	ret = 0;
>  	if (list_empty(&source))
>  		goto out;
>  	/* this function returns # of failed pages */
> -- 
> 1.6.3.3
> 
> 

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