Message-ID: <20170510055317.GA26158@dhcp22.suse.cz>
Date:   Wed, 10 May 2017 07:53:18 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Dan Williams <dan.j.williams@...il.com>
Cc:     linux-mm <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Reza Arbab <arbab@...ux.vnet.ibm.com>,
        Yasuaki Ishimatsu <yasu.isimatu@...il.com>,
        qiuxishi@...wei.com, Kani Toshimitsu <toshi.kani@....com>,
        slaoub@...il.com, Joonsoo Kim <js1304@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Daniel Kiper <daniel.kiper@...cle.com>,
        Igor Mammedov <imammedo@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Balbir Singh <bsingharora@...il.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Tobias Regnery <tobias.regnery@...il.com>,
        Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Subject: Re: [PATCH -v3 0/13] mm: make movable onlining suck less

On Tue 09-05-17 21:43:16, Dan Williams wrote:
> On Fri, Apr 21, 2017 at 5:05 AM, Michal Hocko <mhocko@...nel.org> wrote:
> > Hi,
> > The last version of this series has been posted here [1]. It has seen
> > some more testing (thanks to Reza Arbab and Igor Mammedov[2]), Jerome's
> > and Vlastimil's review resulted in few fixes mostly folded in their
> > respected patches.
> > There are 4 more patches (patch 6+ in this series).  I have checked the
> > most prominent pfn walkers to skip over offline holes and now and I feel
> > more comfortable to have this merged. All the reported issues should be
> > fixed
> >
> > There is still a lot of work on top - namely this implementation doesn't
> > support reonlining to a different zone on the zones boundaries but I
> > will do that in a separate series because this one is getting quite
> > large already and it should work reasonably well now.
> >
> > Joonsoo had some worries about pfn_valid and suggested to change its
> > semantic to return false on offline holes but I would be rally worried
> > to change a established semantic used by a lot of code and so I have
> > introuduced pfn_to_online_page helper instead. If this is seen as a
> > controversial point I would rather drop pfn_to_online_page and related
> > patches as they are not stictly necessary because the code would be
> > similarly broken as now wrt. offline holes.
> >
> > This is a rebase on top of linux-next (next-20170418) and the full
> > series is in git://git.kernel.org/pub/scm/linux/kernel/git/mhocko/mm.git
> > try attempts/rewrite-mem_hotplug branch.
> >
> [..]
> > Any thoughts, complains, suggestions?
> >
> > As a bonus we will get a nice cleanup in the memory hotplug codebase.
> >  arch/ia64/mm/init.c            |  11 +-
> >  arch/powerpc/mm/mem.c          |  12 +-
> >  arch/s390/mm/init.c            |  32 +--
> >  arch/sh/mm/init.c              |  10 +-
> >  arch/x86/mm/init_32.c          |   7 +-
> >  arch/x86/mm/init_64.c          |  11 +-
> >  drivers/base/memory.c          |  79 +++----
> >  drivers/base/node.c            |  58 ++----
> >  include/linux/memory_hotplug.h |  40 +++-
> >  include/linux/mmzone.h         |  44 +++-
> >  include/linux/node.h           |  35 +++-
> >  kernel/memremap.c              |   6 +-
> >  mm/compaction.c                |   5 +-
> >  mm/memory_hotplug.c            | 455 ++++++++++++++---------------------------
> >  mm/page_alloc.c                |  13 +-
> >  mm/page_isolation.c            |  26 ++-
> >  mm/sparse.c                    |  48 ++++-
> >  17 files changed, 407 insertions(+), 485 deletions(-)
> >
> > Shortlog says:
> > Michal Hocko (13):
> >       mm: remove return value from init_currently_empty_zone
> >       mm, memory_hotplug: use node instead of zone in can_online_high_movable
> >       mm: drop page_initialized check from get_nid_for_pfn
> >       mm, memory_hotplug: get rid of is_zone_device_section
> >       mm, memory_hotplug: split up register_one_node
> >       mm, memory_hotplug: consider offline memblocks removable
> >       mm: consider zone which is not fully populated to have holes
> >       mm, compaction: skip over holes in __reset_isolation_suitable
> >       mm: __first_valid_page skip over offline pages
> >       mm, memory_hotplug: do not associate hotadded memory to zones until online
> >       mm, memory_hotplug: replace for_device by want_memblock in arch_add_memory
> >       mm, memory_hotplug: fix the section mismatch warning
> >       mm, memory_hotplug: remove unused cruft after memory hotplug rework
> >
> > [1] http://lkml.kernel.org/r/20170410110351.12215-1-mhocko@kernel.org
> > [2] http://lkml.kernel.org/r/20170410162749.7d7f31c1@nial.brq.redhat.com
> >
> >
> 
> The latest "attempts/rewrite-mem_hotplug" branch passes my regression
> testing if I cherry-pick the following x86/mm fixes from mainline:
> 
> e6ab9c4d4377 x86/mm/64: Fix crash in remove_pagetable()
> 71389703839e mm, zone_device: Replace {get, put}_zone_device_page()
> with a single reference to fix pmem crash

I will make sure those will appear in the mmotm git tree (I will
probably pull the whole tip/x86-mm-for-linus.
 
> You can add:
> 
> Tested-by: Dan Williams <dan.j.williams@...el.com>

Thanks a lot for your testing! I will put your tested-by to patches
where you were on the CC explicitly (and which might affect zone device)
- mm, memory_hotplug: get rid of is_zone_device_section
- mm, memory_hotplug: do not associate hotadded memory to zones until
  online
- mm, memory_hotplug: replace for_device by want_memblock in
  arch_add_memory

Let me know if you want other patches as well.

-- 
Michal Hocko
SUSE Labs

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