linux-kernel - Re: [PATCH v4] mm/hotplug: treat CMA pages as unmovable

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Date:   Wed, 17 Apr 2019 16:06:45 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     Qian Cai <cai@....pw>, akpm@...ux-foundation.org
Cc:     mhocko@...e.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Vlastimil Babka <vbabka@...e.cz>
Subject: Re: [PATCH v4] mm/hotplug: treat CMA pages as unmovable


> Acked-by: Michal Hocko <mhocko@...e.com>
> Acked-by: Vlastimil Babka <vbabka@...e.cz>
> Signed-off-by: Qian Cai <cai@....pw>

Reviewed-by: Oscar Salvador <osalvador@...e.de>

> ---
> 
> v4: Use is_migrate_cma_page() and update the commit log per
> Vlastimil.
> v3: Use a string pointer instead of an array per Michal.
> v2: Borrow some commit log texts.
>     Call dump_page() in the error path.
> 
>  mm/page_alloc.c | 30 ++++++++++++++++++------------
>  1 file changed, 18 insertions(+), 12 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index d96ca5bc555b..c6ce20aaf80b 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -8005,7 +8005,10 @@ void *__init alloc_large_system_hash(const
> char *tablename,
>  bool has_unmovable_pages(struct zone *zone, struct page *page, int
> count,
>  			 int migratetype, int flags)
>  {
> -	unsigned long pfn, iter, found;
> +	unsigned long found;
> +	unsigned long iter = 0;
> +	unsigned long pfn = page_to_pfn(page);
> +	const char *reason = "unmovable page";
>  
>  	/*
>  	 * TODO we could make this much more efficient by not
> checking every
> @@ -8015,17 +8018,20 @@ bool has_unmovable_pages(struct zone *zone,
> struct page *page, int count,
>  	 * can still lead to having bootmem allocations in
> zone_movable.
>  	 */
>  
> -	/*
> -	 * CMA allocations (alloc_contig_range) really need to mark
> isolate
> -	 * CMA pageblocks even when they are not movable in fact so
> consider
> -	 * them movable here.
> -	 */
> -	if (is_migrate_cma(migratetype) &&
> -			is_migrate_cma(get_pageblock_migratetype(pag
> e)))
> -		return false;
> +	if (is_migrate_cma_page(page)) {
> +		/*
> +		 * CMA allocations (alloc_contig_range) really need
> to mark
> +		 * isolate CMA pageblocks even when they are not
> movable in fact
> +		 * so consider them movable here.
> +		 */
> +		if (is_migrate_cma(migratetype))
> +			return false;
> +
> +		reason = "CMA page";
> +		goto unmovable;
> +	}
>  
> -	pfn = page_to_pfn(page);
> -	for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++)
> {
> +	for (found = 0; iter < pageblock_nr_pages; iter++) {
>  		unsigned long check = pfn + iter;
>  
>  		if (!pfn_valid_within(check))
> @@ -8105,7 +8111,7 @@ bool has_unmovable_pages(struct zone *zone,
> struct page *page, int count,
>  unmovable:
>  	WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE);
>  	if (flags & REPORT_FAILURE)
> -		dump_page(pfn_to_page(pfn+iter), "unmovable page");
> +		dump_page(pfn_to_page(pfn + iter), reason);
>  	return true;
>  }
>  
-- 
Oscar Salvador
SUSE L3