Re: [RFC] HWPOISON: soft offlining for non-lru movable page

[Naoya Horiguchi]

On Wed, Jan 18, 2017 at 12:00:54PM +0800, Yisheng Xie wrote:
> This patch is to extends soft offlining framework to support
> non-lru page, which already support migration after
> commit bda807d44454 ("mm: migrate: support non-lru movable page
> migration")
> 
> When memory corrected errors occur on a non-lru movable page,
> we can choose to stop using it by migrating data onto another
> page and disable the original (maybe half-broken) one.
> 
> Signed-off-by: Yisheng Xie <xieyisheng1@xxxxxxxxxx>

It looks OK in my quick glance. I'll do some testing more tomorrow.

Thanks,
Naoya Horiguchi

> ---
>  mm/memory-failure.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 53 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index f283c7e..10043a4 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1527,7 +1527,8 @@ static int get_any_page(struct page *page, unsigned long pfn, int flags)
>  {
>  	int ret = __get_any_page(page, pfn, flags);
>  
> -	if (ret == 1 && !PageHuge(page) && !PageLRU(page)) {
> +	if (ret == 1 && !PageHuge(page) &&
> +	    !PageLRU(page) && !__PageMovable(page)) {
>  		/*
>  		 * Try to free it.
>  		 */
> @@ -1549,6 +1550,54 @@ static int get_any_page(struct page *page, unsigned long pfn, int flags)
>  	return ret;
>  }
>  
> +static int soft_offline_movable_page(struct page *page, int flags)
> +{
> +	int ret;
> +	unsigned long pfn = page_to_pfn(page);
> +	LIST_HEAD(pagelist);
> +
> +	/*
> +	 * This double-check of PageHWPoison is to avoid the race with
> +	 * memory_failure(). See also comment in __soft_offline_page().
> +	 */
> +	lock_page(page);
> +	if (PageHWPoison(page)) {
> +		unlock_page(page);
> +		put_hwpoison_page(page);
> +		pr_info("soft offline: %#lx movable page already poisoned\n",
> +			pfn);
> +		return -EBUSY;
> +	}
> +	unlock_page(page);
> +
> +	ret = isolate_movable_page(page, ISOLATE_UNEVICTABLE);
> +	/*
> +	 * get_any_page() and isolate_movable_page() takes a refcount each,
> +	 * so need to drop one here.
> +	 */
> +	put_hwpoison_page(page);
> +	if (!ret) {
> +		pr_info("soft offline: %#lx movable page failed to isolate\n",
> +			pfn);
> +		return -EBUSY;
> +	}
> +
> +	list_add(&page->lru, &pagelist);
> +	ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
> +			    MIGRATE_SYNC, MR_MEMORY_FAILURE);
> +	if (ret) {
> +		if (!list_empty(&pagelist))
> +			putback_movable_pages(&pagelist);
> +
> +		pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
> +			pfn, ret, page->flags);
> +		if (ret > 0)
> +			ret = -EIO;
> +	}
> +
> +	return ret;
> +}
> +
>  static int soft_offline_huge_page(struct page *page, int flags)
>  {
>  	int ret;
> @@ -1705,8 +1754,10 @@ static int soft_offline_in_use_page(struct page *page, int flags)
>  
>  	if (PageHuge(page))
>  		ret = soft_offline_huge_page(page, flags);
> -	else
> +	else if (PageLRU(page))
>  		ret = __soft_offline_page(page, flags);
> +	else
> +		ret = soft_offline_movable_page(page, flags);
>  
>  	return ret;
>  }
> -- 
> 1.7.12.4
>