RE: [PATCH v4 02/25] mm/memory_hotplug: Allow check_hotplug_memory_addressable to be called from drivers

[Alastair D'Silva]

> -----Original Message-----
> From: Dan Williams <dan.j.williams@xxxxxxxxx>
> Sent: Wednesday, 1 April 2020 7:48 PM
> To: Alastair D'Silva <alastair@xxxxxxxxxxx>
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> Subject: Re: [PATCH v4 02/25] mm/memory_hotplug: Allow
> check_hotplug_memory_addressable to be called from drivers
> 
> On Sun, Mar 29, 2020 at 10:23 PM Alastair D'Silva <alastair@xxxxxxxxxxx>
> wrote:
> >
> > When setting up OpenCAPI connected persistent memory, the range check
> > may not be performed until quite late (or perhaps not at all, if the
> > user does not establish a DAX device).
> >
> > This patch makes the range check callable so we can perform the check
> > while probing the OpenCAPI Persistent Memory device.
> >
> > Signed-off-by: Alastair D'Silva <alastair@xxxxxxxxxxx>
> > Reviewed-by: Andrew Donnellan <ajd@xxxxxxxxxxxxx>
> > ---
> >  include/linux/memory_hotplug.h | 5 +++++
> >  mm/memory_hotplug.c            | 4 ++--
> >  2 files changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/memory_hotplug.h
> > b/include/linux/memory_hotplug.h index f4d59155f3d4..9a19ae0d7e31
> > 100644
> > --- a/include/linux/memory_hotplug.h
> > +++ b/include/linux/memory_hotplug.h
> > @@ -337,6 +337,11 @@ static inline void __remove_memory(int nid, u64
> > start, u64 size) {}  extern void set_zone_contiguous(struct zone
> > *zone);  extern void clear_zone_contiguous(struct zone *zone);
> >
> > +#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
> > +int check_hotplug_memory_addressable(unsigned long pfn,
> > +                                    unsigned long nr_pages); #endif
> > +/* CONFIG_MEMORY_HOTPLUG_SPARSE */
> 
> Let's move this to include/linux/memory.h with the other
> CONFIG_MEMORY_HOTPLUG_SPARSE declarations, and add a dummy
> implementation for the CONFIG_MEMORY_HOTPLUG_SPARSE=n case.
> 
> Also, this patch can be squashed with the next one, no need for it to be
> stand alone.
> 

Ok

> 
> > +
> >  extern void __ref free_area_init_core_hotplug(int nid);  extern int
> > __add_memory(int nid, u64 start, u64 size);  extern int add_memory(int
> > nid, u64 start, u64 size); diff --git a/mm/memory_hotplug.c
> > b/mm/memory_hotplug.c index 0a54ffac8c68..14945f033594 100644
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -276,8 +276,8 @@ static int check_pfn_span(unsigned long pfn,
> unsigned long nr_pages,
> >         return 0;
> >  }
> >
> > -static int check_hotplug_memory_addressable(unsigned long pfn,
> > -                                           unsigned long nr_pages)
> > +int check_hotplug_memory_addressable(unsigned long pfn,
> > +                                    unsigned long nr_pages)
> >  {
> >         const u64 max_addr = PFN_PHYS(pfn + nr_pages) - 1;
> >
> > --
> > 2.24.1
> >

-- 
Alastair D'Silva           mob: 0423 762 819
skype: alastair_dsilva     msn: alastair@xxxxxxxxxxx
blog: http://alastair.d-silva.org    Twitter: @EvilDeece