Re: [PATCH 3/9] soft-offline: use migrate_pages() instead ofmigrate_huge_page()

[Chen Gong]

On Thu, Feb 21, 2013 at 02:41:42PM -0500, Naoya Horiguchi wrote:
> Date: Thu, 21 Feb 2013 14:41:42 -0500
> From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
> To: linux-mm@xxxxxxxxx
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Mel Gorman <mel@xxxxxxxxx>,
>  Hugh Dickins <hughd@xxxxxxxxxx>, KOSAKI Motohiro
>  <kosaki.motohiro@xxxxxxxxxxxxxx>, Andi Kleen <andi@xxxxxxxxxxxxxx>,
>  linux-kernel@xxxxxxxxxxxxxxx
> Subject: [PATCH 3/9] soft-offline: use migrate_pages() instead of
>  migrate_huge_page()
> 
> Currently migrate_huge_page() takes a pointer to a hugepage to be
> migrated as an argument, instead of taking a pointer to the list of
> hugepages to be migrated. This behavior was introduced in commit
> 189ebff28 ("hugetlb: simplify migrate_huge_page()"), and was OK
> because until now hugepage migration is enabled only for soft-offlining
> which takes only one hugepage in a single call.
> 
> But the situation will change in the later patches in this series
> which enable other users of page migration to support hugepage migration.
> They can kick migration for both of normal pages and hugepages
> in a single call, so we need to go back to original implementation
> of using linked lists to collect the hugepages to be migrated.
> 
> Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
> ---
>  mm/memory-failure.c | 20 ++++++++++++++++----
>  mm/migrate.c        |  2 ++
>  2 files changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git v3.8.orig/mm/memory-failure.c v3.8/mm/memory-failure.c
> index bc126f6..01e4676 100644
> --- v3.8.orig/mm/memory-failure.c
> +++ v3.8/mm/memory-failure.c
> @@ -1467,6 +1467,7 @@ static int soft_offline_huge_page(struct page *page, int flags)
>  	int ret;
>  	unsigned long pfn = page_to_pfn(page);
>  	struct page *hpage = compound_head(page);
> +	LIST_HEAD(pagelist);
>  
>  	/* Synchronized using the page lock with memory_failure() */
>  	lock_page(hpage);
> @@ -1479,13 +1480,24 @@ static int soft_offline_huge_page(struct page *page, int flags)
>  	unlock_page(hpage);
>  
>  	/* Keep page count to indicate a given hugepage is isolated. */
> -	ret = migrate_huge_page(hpage, new_page, MPOL_MF_MOVE_ALL, false,
> -				MIGRATE_SYNC);
> -	put_page(hpage);
> +	list_move(&hpage->lru, &pagelist);
> +	ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, false,
> +				MIGRATE_SYNC, MR_MEMORY_FAILURE);
>  	if (ret) {
>  		pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
>  			pfn, ret, page->flags);
> -		return ret;
> +		/*
> +		 * We know that soft_offline_huge_page() tries to migrate
> +		 * only one hugepage pointed to by hpage, so we need not
> +		 * run through the pagelist here.
> +		 */
> +		putback_active_hugepage(hpage);
> +		if (ret > 0)
> +			ret = -EIO;
> +	} else {
> +		set_page_hwpoison_huge_page(hpage);
> +		dequeue_hwpoisoned_huge_page(hpage);
> +		atomic_long_add(1<<compound_trans_order(hpage), &mce_bad_pages);

mce_bad_pages has been substituted by num_poisoned_pages.

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