linux-kernel - Re: [PATCH] memory_hotplug: always initialize pageblock bitmap.

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Date:	Mon, 12 May 2008 10:55:00 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Heiko Carstens <heiko.carstens@...ibm.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Whitcroft <apw@...dowen.org>,
	Dave Hansen <haveblue@...ibm.com>,
	Gerald Schaefer <gerald.schaefer@...ibm.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] memory_hotplug: always initialize pageblock bitmap.

On Sat, 10 May 2008 14:45:01 +0200
Heiko Carstens <heiko.carstens@...ibm.com> wrote:
> > Recently, I added a check "zone's start_pfn < pfn < zone's end"
> > to memmap_init_zone()'s usemap initialization for !SPARSEMEM case bug FIX.
> > (and I think the fix itself is sane.)
> 
> Oh, you broke memory hot-add on -stable ;)
>
Ah yes, my mistake. Very sorry, (but stable was also broken if !SPARSEMEM)
 
> > How about calling grow_pgdat_span()/grow_zone_span() from __add_zone() ?
> 
> Like this?
> 
> Note that this patch is on top of the other patch I already sent, but
> reverts it...
> 
> This works for me. A final version (if this is acceptable) should move
> the grow* functions also.
> 
> ---
>  mm/memory_hotplug.c |   28 +++++++++++++++++++---------
>  mm/page_alloc.c     |    3 +--
>  2 files changed, 20 insertions(+), 11 deletions(-)
> 
> Index: linux-2.6/mm/memory_hotplug.c
> ===================================================================
> --- linux-2.6.orig/mm/memory_hotplug.c
> +++ linux-2.6/mm/memory_hotplug.c
> @@ -159,17 +159,33 @@ void register_page_bootmem_info_node(str
>  }
>  #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
>  
> +static void grow_zone_span(struct zone *zone, unsigned long start_pfn,
> +			   unsigned long end_pfn);
> +static void grow_pgdat_span(struct pglist_data *pgdat,
> +			    unsigned long start_pfn, unsigned long end_pfn);
> +
>  static int __add_zone(struct zone *zone, unsigned long phys_start_pfn)
>  {
>  	struct pglist_data *pgdat = zone->zone_pgdat;
>  	int nr_pages = PAGES_PER_SECTION;
>  	int nid = pgdat->node_id;
>  	int zone_type;
> +	unsigned long flags;
>  
>  	zone_type = zone - pgdat->node_zones;
> -	if (!zone->wait_table)
> -		return init_currently_empty_zone(zone, phys_start_pfn,
> -						 nr_pages, MEMMAP_HOTPLUG);
> +	if (!zone->wait_table) {
> +		int ret;
> +
> +		ret = init_currently_empty_zone(zone, phys_start_pfn,
> +						nr_pages, MEMMAP_HOTPLUG);
> +		if (ret)
> +			return ret;
> +	}
> +	pgdat_resize_lock(zone->zone_pgdat, &flags);
> +	grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
> +	grow_pgdat_span(zone->zone_pgdat, phys_start_pfn,
> +			phys_start_pfn + nr_pages);
> +	pgdat_resize_unlock(zone->zone_pgdat, &flags);
>  	memmap_init_zone(nr_pages, nid, zone_type,
>  			 phys_start_pfn, MEMMAP_HOTPLUG);
>  	return 0;
seems good. I'll try this logic on my ia64 box, which allows
NUMA-node hotplug.

Thank you!
-Kame

> @@ -363,7 +379,6 @@ static int online_pages_range(unsigned l
>  
>  int online_pages(unsigned long pfn, unsigned long nr_pages)
>  {
> -	unsigned long flags;
>  	unsigned long onlined_pages = 0;
>  	struct zone *zone;
>  	int need_zonelists_rebuild = 0;
> @@ -391,11 +406,6 @@ int online_pages(unsigned long pfn, unsi
>  	 * memory_block->state_mutex.
>  	 */
>  	zone = page_zone(pfn_to_page(pfn));
> -	pgdat_resize_lock(zone->zone_pgdat, &flags);
> -	grow_zone_span(zone, pfn, pfn + nr_pages);
> -	grow_pgdat_span(zone->zone_pgdat, pfn, pfn + nr_pages);
> -	pgdat_resize_unlock(zone->zone_pgdat, &flags);
> -
>  	/*
>  	 * If this zone is not populated, then it is not in zonelist.
>  	 * This means the page allocator ignores this zone.
> Index: linux-2.6/mm/page_alloc.c
> ===================================================================
> --- linux-2.6.orig/mm/page_alloc.c
> +++ linux-2.6/mm/page_alloc.c
> @@ -2862,8 +2862,6 @@ __meminit int init_currently_empty_zone(
>  
>  	zone->zone_start_pfn = zone_start_pfn;
>  
> -	memmap_init(size, pgdat->node_id, zone_idx(zone), zone_start_pfn);
> -
>  	zone_init_free_lists(zone);
>  
>  	return 0;
> @@ -3433,6 +3431,7 @@ static void __paginginit free_area_init_
>  		ret = init_currently_empty_zone(zone, zone_start_pfn,
>  						size, MEMMAP_EARLY);
>  		BUG_ON(ret);
> +		memmap_init(size, nid, j, zone_start_pfn);
>  		zone_start_pfn += size;
>  	}
>  }
> 

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