Re: + mem-hotplug-use-nodes-that-contain-memory-as-mask-in-new_node_page.patch added to -mm tree

Re: + mem-hotplug-use-nodes-that-contain-memory-as-mask-in-new_node_page.patch added to -mm tree

[Michal Hocko]

On Tue 27-09-16 15:07:09, Andrew Morton wrote:
> From: Li Zhong <zhong@linux.vnet.ibm.com>
> Subject: mem-hotplug: use nodes that contain memory as mask in new_node_page()
> 
> 9bb627be47a5 ("mem-hotplug: don't clear the only node in new_node_page()")
> prevents allocating from an empty nodemask, but as David points out, it is
> still wrong.  As node_online_map may include memoryless nodes, only
> allocating from these nodes is meaningless.
> 
> This patch uses node_states[N_MEMORY] mask to prevent the above case.
> 
> Fixes: 9bb627be47a5 ("mem-hotplug: don't clear the only node in new_node_page()")
> Fixes: 394e31d2ceb4 ("mem-hotplug: alloc new page from a nearest neighbor node when mem-offline")
> Link: http://lkml.kernel.org/r/1474447117.28370.6.camel@TP420
> Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
> Suggested-by: David Rientjes <rientjes@google.com>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> Cc: Michal Hocko <mhocko@suse.cz>

Acked-by: Michal Hocko <mhocko@suse.com>

> Cc: John Allen <jallen@linux.vnet.ibm.com>
> Cc: Xishi Qiu <qiuxishi@huawei.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
> 
>  mm/memory_hotplug.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff -puN mm/memory_hotplug.c~mem-hotplug-use-nodes-that-contain-memory-as-mask-in-new_node_page mm/memory_hotplug.c
> --- a/mm/memory_hotplug.c~mem-hotplug-use-nodes-that-contain-memory-as-mask-in-new_node_page
> +++ a/mm/memory_hotplug.c
> @@ -1555,8 +1555,8 @@ static struct page *new_node_page(struct
>  {
>  	gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
>  	int nid = page_to_nid(page);
> -	nodemask_t nmask = node_online_map;
> -	struct page *new_page;
> +	nodemask_t nmask = node_states[N_MEMORY];
> +	struct page *new_page = NULL;
>  
>  	/*
>  	 * TODO: allocate a destination hugepage from a nearest neighbor node,
> @@ -1567,14 +1567,14 @@ static struct page *new_node_page(struct
>  		return alloc_huge_page_node(page_hstate(compound_head(page)),
>  					next_node_in(nid, nmask));
>  
> -	if (nid != next_node_in(nid, nmask))
> -		node_clear(nid, nmask);
> +	node_clear(nid, nmask);
>  
>  	if (PageHighMem(page)
>  	    || (zone_idx(page_zone(page)) == ZONE_MOVABLE))
>  		gfp_mask |= __GFP_HIGHMEM;
>  
> -	new_page = __alloc_pages_nodemask(gfp_mask, 0,
> +	if (!nodes_empty(nmask))
> +		new_page = __alloc_pages_nodemask(gfp_mask, 0,
>  					node_zonelist(nid, gfp_mask), &nmask);
>  	if (!new_page)
>  		new_page = __alloc_pages(gfp_mask, 0,
> _
> 
> Patches currently in -mm which might be from zhong@linux.vnet.ibm.com are
> 
> mem-hotplug-use-nodes-that-contain-memory-as-mask-in-new_node_page.patch

-- 
Michal Hocko
SUSE Labs

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