Re: [PATCH 3/4] mm/memory_hotplug: Get rid of link_mem_sections
From: Oscar Salvador
Date: Mon Jun 25 2018 - 13:34:52 EST
On Mon, Jun 25, 2018 at 06:04:36PM +0100, Jonathan Cameron wrote:
> On Fri, 1 Jun 2018 14:53:20 +0200
> <osalvador@xxxxxxxxxxxxxxxxxx> wrote:
>
> > From: Oscar Salvador <osalvador@xxxxxxx>
> >
> > 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@xxxxxxx>
> > ---
> > 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@xxxxxxxxxxxxxxxxxx>
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