linux-kernel - RE: [PATCH v4 02/25] mm/memory_hotplug: Allow check_hotplug_memory

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Message-ID: <2e7501d608a7$ea00cd10$be026730$@d-silva.org>
Date:   Thu, 2 Apr 2020 15:33:43 +1100
From:   "Alastair D'Silva" <alastair@...ilva.org>
To:     "'Dan Williams'" <dan.j.williams@...el.com>
Cc:     "'Aneesh Kumar K . V'" <aneesh.kumar@...ux.ibm.com>,
        "'Oliver O'Halloran'" <oohall@...il.com>,
        "'Benjamin Herrenschmidt'" <benh@...nel.crashing.org>,
        "'Paul Mackerras'" <paulus@...ba.org>,
        "'Michael Ellerman'" <mpe@...erman.id.au>,
        "'Frederic Barrat'" <fbarrat@...ux.ibm.com>,
        "'Andrew Donnellan'" <ajd@...ux.ibm.com>,
        "'Arnd Bergmann'" <arnd@...db.de>,
        "'Greg Kroah-Hartman'" <gregkh@...uxfoundation.org>,
        "'Vishal Verma'" <vishal.l.verma@...el.com>,
        "'Dave Jiang'" <dave.jiang@...el.com>,
        "'Ira Weiny'" <ira.weiny@...el.com>,
        "'Andrew Morton'" <akpm@...ux-foundation.org>,
        "'Mauro Carvalho Chehab'" <mchehab+samsung@...nel.org>,
        "'David S. Miller'" <davem@...emloft.net>,
        "'Rob Herring'" <robh@...nel.org>,
        "'Anton Blanchard'" <anton@...abs.org>,
        "'Krzysztof Kozlowski'" <krzk@...nel.org>,
        "'Mahesh Salgaonkar'" <mahesh@...ux.vnet.ibm.com>,
        "'Madhavan Srinivasan'" <maddy@...ux.vnet.ibm.com>,
        "'Cédric Le Goater'" <clg@...d.org>,
        "'Anju T Sudhakar'" <anju@...ux.vnet.ibm.com>,
        "'Hari Bathini'" <hbathini@...ux.ibm.com>,
        "'Thomas Gleixner'" <tglx@...utronix.de>,
        "'Greg Kurz'" <groug@...d.org>,
        "'Nicholas Piggin'" <npiggin@...il.com>,
        "'Masahiro Yamada'" <yamada.masahiro@...ionext.com>,
        "'Alexey Kardashevskiy'" <aik@...abs.ru>,
        "'Linux Kernel Mailing List'" <linux-kernel@...r.kernel.org>,
        "'linuxppc-dev'" <linuxppc-dev@...ts.ozlabs.org>,
        "'linux-nvdimm'" <linux-nvdimm@...ts.01.org>,
        "'Linux MM'" <linux-mm@...ck.org>
Subject: RE: [PATCH v4 02/25] mm/memory_hotplug: Allow check_hotplug_memory_addressable to be called from drivers

> -----Original Message-----
> From: Dan Williams <dan.j.williams@...el.com>
> Sent: Wednesday, 1 April 2020 7:48 PM
> To: Alastair D'Silva <alastair@...ilva.org>
> Cc: Aneesh Kumar K . V <aneesh.kumar@...ux.ibm.com>; Oliver O'Halloran
> <oohall@...il.com>; Benjamin Herrenschmidt
> <benh@...nel.crashing.org>; Paul Mackerras <paulus@...ba.org>; Michael
> Ellerman <mpe@...erman.id.au>; Frederic Barrat <fbarrat@...ux.ibm.com>;
> Andrew Donnellan <ajd@...ux.ibm.com>; Arnd Bergmann
> <arnd@...db.de>; Greg Kroah-Hartman <gregkh@...uxfoundation.org>;
> Vishal Verma <vishal.l.verma@...el.com>; Dave Jiang
> <dave.jiang@...el.com>; Ira Weiny <ira.weiny@...el.com>; Andrew Morton
> <akpm@...ux-foundation.org>; Mauro Carvalho Chehab
> <mchehab+samsung@...nel.org>; David S. Miller <davem@...emloft.net>;
> Rob Herring <robh@...nel.org>; Anton Blanchard <anton@...abs.org>;
> Krzysztof Kozlowski <krzk@...nel.org>; Mahesh Salgaonkar
> <mahesh@...ux.vnet.ibm.com>; Madhavan Srinivasan
> <maddy@...ux.vnet.ibm.com>; Cédric Le Goater <clg@...d.org>; Anju T
> Sudhakar <anju@...ux.vnet.ibm.com>; Hari Bathini
> <hbathini@...ux.ibm.com>; Thomas Gleixner <tglx@...utronix.de>; Greg
> Kurz <groug@...d.org>; Nicholas Piggin <npiggin@...il.com>; Masahiro
> Yamada <yamada.masahiro@...ionext.com>; Alexey Kardashevskiy
> <aik@...abs.ru>; Linux Kernel Mailing List <linux-kernel@...r.kernel.org>;
> linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>; linux-nvdimm <linux-
> nvdimm@...ts.01.org>; Linux MM <linux-mm@...ck.org>
> 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@...ilva.org>
> 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@...ilva.org>
> > Reviewed-by: Andrew Donnellan <ajd@...ux.ibm.com>
> > ---
> >  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@...ilva.org
blog: http://alastair.d-silva.org    Twitter: @EvilDeece