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Date:   Mon, 25 Jun 2018 19:34:44 +0200
From:   Oscar Salvador <osalvador@techadventures.net>
To:     Jonathan Cameron <jonathan.cameron@huawei.com>
Cc:     akpm@linux-foundation.org, mhocko@suse.com, vbabka@suse.cz,
        pasha.tatashin@oracle.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Oscar Salvador <osalvador@suse.de>
Subject: Re: [PATCH 3/4] mm/memory_hotplug: Get rid of link_mem_sections
Message-ID: <20180625173444.GA23268@techadventures.net>
References: <20180601125321.30652-1-osalvador@techadventures.net>
 <20180601125321.30652-4-osalvador@techadventures.net>
 <20180625180436.000049ac@huawei.com>
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On Mon, Jun 25, 2018 at 06:04:36PM +0100, Jonathan Cameron wrote:
> On Fri, 1 Jun 2018 14:53:20 +0200
> <osalvador@techadventures.net> wrote:
> 
> > From: Oscar Salvador <osalvador@suse.de>
> > 
> > link_mem_sections() and walk_memory_range() share most of the code,
> > so we can use walk_memory_range() with a callback to register_mem_sect_under_node()
> > instead of using link_mem_sections().
> > 
> > To control whether the node id must be check, two new functions has been added:
> > 
> > register_mem_sect_under_node_nocheck_node()
> > and
> > register_mem_sect_under_node_check_node()
> > 
> > They both call register_mem_sect_under_node_check() with
> > the parameter check_nid set to true or false.
> > 
> > Signed-off-by: Oscar Salvador <osalvador@suse.de>
> > ---
> >  drivers/base/node.c  | 47 ++++++++++-------------------------------------
> >  include/linux/node.h | 21 +++++++++------------
> >  mm/memory_hotplug.c  |  8 ++++----
> >  3 files changed, 23 insertions(+), 53 deletions(-)
> > 
> > diff --git a/drivers/base/node.c b/drivers/base/node.c
> > index a5e821d09656..248c712e8de5 100644
> > --- a/drivers/base/node.c
> > +++ b/drivers/base/node.c
> > @@ -398,6 +398,16 @@ static int __ref get_nid_for_pfn(unsigned long pfn)
> >  	return pfn_to_nid(pfn);
> >  }
> >  
> > +int register_mem_sect_under_node_check_node(struct memory_block *mem_blk, void *nid)
> > +{
> > +	return register_mem_sect_under_node (mem_blk, *(int *)nid, true);
> > +}
> > +
> > +int register_mem_sect_under_node_nocheck_node(struct memory_block *mem_blk, void *nid)
> > +{
> > +	return register_mem_sect_under_node (mem_blk, *(int *)nid, false);
> > +}
> > +
> >  /* register memory section under specified node if it spans that node */
> >  int register_mem_sect_under_node(struct memory_block *mem_blk, int nid,
> >  				 bool check_nid)
> > @@ -490,43 +500,6 @@ int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
> >  	return 0;
> >  }
> >  
> > -int link_mem_sections(int nid, unsigned long start_pfn, unsigned long nr_pages,
> > -		      bool check_nid)
> > -{
> > -	unsigned long end_pfn = start_pfn + nr_pages;
> > -	unsigned long pfn;
> > -	struct memory_block *mem_blk = NULL;
> > -	int err = 0;
> > -
> > -	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
> > -		unsigned long section_nr = pfn_to_section_nr(pfn);
> > -		struct mem_section *mem_sect;
> > -		int ret;
> > -
> > -		if (!present_section_nr(section_nr))
> > -			continue;
> > -		mem_sect = __nr_to_section(section_nr);
> > -
> > -		/* same memblock ? */
> > -		if (mem_blk)
> > -			if ((section_nr >= mem_blk->start_section_nr) &&
> > -			    (section_nr <= mem_blk->end_section_nr))
> > -				continue;
> > -
> > -		mem_blk = find_memory_block_hinted(mem_sect, mem_blk);
> > -
> > -		ret = register_mem_sect_under_node(mem_blk, nid, check_nid);
> > -		if (!err)
> > -			err = ret;
> > -
> > -		/* discard ref obtained in find_memory_block() */
> > -	}
> > -
> > -	if (mem_blk)
> > -		kobject_put(&mem_blk->dev.kobj);
> > -	return err;
> > -}
> > -
> >  #ifdef CONFIG_HUGETLBFS
> >  /*
> >   * Handle per node hstate attribute [un]registration on transistions
> > diff --git a/include/linux/node.h b/include/linux/node.h
> > index 6d336e38d155..1158bea9be52 100644
> > --- a/include/linux/node.h
> > +++ b/include/linux/node.h
> > @@ -31,19 +31,11 @@ struct memory_block;
> >  extern struct node *node_devices[];
> >  typedef  void (*node_registration_func_t)(struct node *);
> >  
> > -#if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_NUMA)
> > -extern int link_mem_sections(int nid, unsigned long start_pfn,
> > -			     unsigned long nr_pages, bool check_nid);
> > -#else
> > -static inline int link_mem_sections(int nid, unsigned long start_pfn,
> > -				    unsigned long nr_pages, bool check_nid)
> > -{
> > -	return 0;
> > -}
> > -#endif
> > -
> >  extern void unregister_node(struct node *node);
> >  #ifdef CONFIG_NUMA
> > +#if defined(CONFIG_MEMORY_HOTPLUG_SPARSE)
> > +extern int register_mem_sect_under_node_check_node(struct memory_block *mem_blk, void *nid);
> > +#endif
> >  /* Core of the node registration - only memory hotplug should use this */
> >  extern int __register_one_node(int nid);
> >  
> > @@ -54,12 +46,17 @@ static inline int register_one_node(int nid)
> >  
> >  	if (node_online(nid)) {
> >  		struct pglist_data *pgdat = NODE_DATA(nid);
> > +		unsigned long start = pgdat->node_start_pfn;
> > +		unsigned long size = pgdat->node_spanned_pages;
> >  
> >  		error = __register_one_node(nid);
> >  		if (error)
> >  			return error;
> >  		/* link memory sections under this node */
> > -		error = link_mem_sections(nid, pgdat->node_start_pfn, pgdat->node_spanned_pages, true);
> > +#if defined(CONFIG_MEMORY_HOTPLUG_SPARSE)
> > +		error = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1),
> > +					(void *)&nid, register_mem_sect_under_node_check_node);
> > +#endif
> Apologies, my previous testing was clearly garbage.
> 
> Looks like we take the node pfns then shift them again.  Result on my system is we only get as far as pfn 22
> which is still in the first memory block so rest of them are never successfully added.
> Replacing with 
> 
> error = walk_memory_range(start, start + size - 1, ...
> 
> works much better and lets me test Lorenzo's patch which is what I was really trying to do today.
> 
> Sorry again for the incorrect previous tested-by.

Hi Jonathan,

this was fixed in v2.
Please, see: <20180622111839.10071-1-osalvador@techadventures.net>

Thanks

Oscar Salvador

> 
> Thanks,
> 
> Jonathan
> 
> 
> >  	}
> >  
> >  	return error;
> > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> > index f84ef96175ab..ac21dc506b84 100644
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -40,6 +40,8 @@
> >  
> >  #include "internal.h"
> >  
> > +extern int register_mem_sect_under_node_nocheck_node(struct memory_block *mem_blk, void *nid);
> > +
> >  /*
> >   * online_page_callback contains pointer to current page onlining function.
> >   * Initially it is generic_online_page(). If it is required it could be
> > @@ -1118,7 +1120,6 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online)
> >  	u64 start, size;
> >  	bool new_node;
> >  	int ret;
> > -	unsigned long start_pfn, nr_pages;
> >  
> >  	start = res->start;
> >  	size = resource_size(res);
> > @@ -1157,9 +1158,8 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online)
> >  	}
> >  
> >  	/* link memory sections under this node.*/
> > -	start_pfn = start >> PAGE_SHIFT;
> > -	nr_pages = size >> PAGE_SHIFT;
> > -	ret = link_mem_sections(nid, start_pfn, nr_pages, false);
> > +	ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1),
> > +				(void *)&nid, register_mem_sect_under_node_nocheck_node);
> >  	if (ret)
> >  		goto register_fail;
> >  
> 
> 

-- 
Oscar Salvador
SUSE L3