linux-kernel - Re: [PATCH v4 10/11] mm/memory-failure: remove a wrapper for alloc_migration

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Date:   Tue, 7 Jul 2020 13:48:29 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     js1304@...il.com
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, kernel-team@....com,
        Vlastimil Babka <vbabka@...e.cz>,
        Christoph Hellwig <hch@...radead.org>,
        Roman Gushchin <guro@...com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v4 10/11] mm/memory-failure: remove a wrapper for
 alloc_migration_target()

On Tue 07-07-20 16:44:48, Joonsoo Kim wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@....com>
> 
> There is a well-defined standard migration target callback. Use it
> directly.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
> ---
>  mm/memory-failure.c | 18 ++++++------------
>  1 file changed, 6 insertions(+), 12 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 609d42b6..3b89804 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1677,16 +1677,6 @@ int unpoison_memory(unsigned long pfn)
>  }
>  EXPORT_SYMBOL(unpoison_memory);
>  
> -static struct page *new_page(struct page *p, unsigned long private)
> -{
> -	struct migration_target_control mtc = {
> -		.nid = page_to_nid(p),
> -		.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
> -	};
> -
> -	return alloc_migration_target(p, (unsigned long)&mtc);
> -}
> -
>  /*
>   * Safely get reference count of an arbitrary page.
>   * Returns 0 for a free page, -EIO for a zero refcount page
> @@ -1793,6 +1783,10 @@ static int __soft_offline_page(struct page *page)
>  	const char *msg_page[] = {"page", "hugepage"};
>  	bool huge = PageHuge(page);
>  	LIST_HEAD(pagelist);
> +	struct migration_target_control mtc = {
> +		.nid = NUMA_NO_NODE,
> +		.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
> +	};

Is NUMA_NO_NODE really intended here? The original code has preferred to
stay on the same node. If this is intentional then the changelog should
be explicit about that.

>  
>  	/*
>  	 * Check PageHWPoison again inside page lock because PageHWPoison
> @@ -1829,8 +1823,8 @@ static int __soft_offline_page(struct page *page)
>  	}
>  
>  	if (isolate_page(hpage, &pagelist)) {
> -		ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
> -					MIGRATE_SYNC, MR_MEMORY_FAILURE);
> +		ret = migrate_pages(&pagelist, alloc_migration_target, NULL,
> +			(unsigned long)&mtc, MIGRATE_SYNC, MR_MEMORY_FAILURE);
>  		if (!ret) {
>  			bool release = !huge;
>  
> -- 
> 2.7.4
> 

-- 
Michal Hocko
SUSE Labs