Re: [PATCH 2/3] do_migrate_range: exit loop if not_managed is true.

[Wu Fengguang <fengguang.wu@intel.com>]

On Thu, Oct 21, 2010 at 09:28:20PM +0800, Bob Liu wrote:
> If not_managed is true all pages will be putback to lru, so
> break the loop earlier to skip other pages isolate.

It's good fix in itself. However it's normal for isolate_lru_page() to
fail at times (when there are active reclaimers). 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.

> Signed-off-by: Bob Liu <lliubbo@gmail.com>
> ---
>  mm/memory_hotplug.c |   10 ++++++----
>  1 files changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index d4e940a..4f72184 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -709,15 +709,17 @@ 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);
>  			dump_page(page);
>  #endif
> +			/* Becasue we don't have big zone->lock. we should
> +			   check this again here. */
> +			if (page_count(page)) {
> +				not_managed++;
> +				break;
> +			}
>  		}
>  	}
>  	ret = -EBUSY;
> -- 
> 1.5.6.3

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