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[209.85.220.65]) by mx.google.com with SMTPS id o4sor247021oia.24.2019.04.17.19.09.24 for (Google Transport Security); Wed, 17 Apr 2019 19:09:24 -0700 (PDT) Received-SPF: pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@intel-com.20150623.gappssmtp.com header.s=20150623 header.b=sWBJ4MP4; spf=pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dan.j.williams@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=WrLS7c6kahvwclZJMhG+EEBp9/3p/FOJcV7sIRhk688=; b=sWBJ4MP4aMbDjfMOL2XmESU3BP1NUeCYIIgWZvm8bnnn2yTsIA4nOkaJ4ujF3TGAQL V7Bvewsg7Z+zFnK7uufCUElZo1lFGESS6DPnGlrzZo57bY7JtK/xauERnePYfPo1QDVH R7W5isQJDZBGsz+/Z/QRdBGGahMkJ1wjjC/51vqskOVhveFg3ETdoXFkYfJhvFyO/VY1 Oh8zwzYpMOaFxrQ92EVfnBRB7oY6ydppKS6DaSBozcTfRk8OJTF/q5RivIIZBRulYXFf qnEnAcBSLCYeKnMyRYBUwzt0WqFSYWJSm9HihsaqQE6JrXV5WOCM6wal7q8J1yD08aXs o12A== X-Google-Smtp-Source: APXvYqxBRLry2uehHtUIkQ1eBS/Fg07FCXB2FZ6fmtn5pcgldkBocOuARUVj5a3Sv2b8a/RLFyKNOhEvUY0nxxYuSLU= X-Received: by 2002:aca:f581:: with SMTP id t123mr443431oih.0.1555553364394; Wed, 17 Apr 2019 19:09:24 -0700 (PDT) MIME-Version: 1.0 References: <155552633539.2015392.2477781120122237934.stgit@dwillia2-desk3.amr.corp.intel.com> <20190417150331.90219ca42a1c0db8632d0fd5@linux-foundation.org> In-Reply-To: From: Dan Williams Date: Wed, 17 Apr 2019 19:09:12 -0700 Message-ID: Subject: Re: [PATCH v6 00/12] mm: Sub-section memory hotplug support To: Andrew Morton Cc: David Hildenbrand , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Logan Gunthorpe , Toshi Kani , Jeff Moyer , Michal Hocko , Vlastimil Babka , stable , Linux MM , linux-nvdimm , Linux Kernel Mailing List , osalvador@suse.de Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Apr 17, 2019 at 3:59 PM Dan Williams wrote: > > On Wed, Apr 17, 2019 at 3:04 PM Andrew Morton wrote: > > > > On Wed, 17 Apr 2019 11:38:55 -0700 Dan Williams wrote: > > > > > The memory hotplug section is an arbitrary / convenient unit for memory > > > hotplug. 'Section-size' units have bled into the user interface > > > ('memblock' sysfs) and can not be changed without breaking existing > > > userspace. The section-size constraint, while mostly benign for typical > > > memory hotplug, has and continues to wreak havoc with 'device-memory' > > > use cases, persistent memory (pmem) in particular. Recall that pmem uses > > > devm_memremap_pages(), and subsequently arch_add_memory(), to allocate a > > > 'struct page' memmap for pmem. However, it does not use the 'bottom > > > half' of memory hotplug, i.e. never marks pmem pages online and never > > > exposes the userspace memblock interface for pmem. This leaves an > > > opening to redress the section-size constraint. > > > > v6 and we're not showing any review activity. Who would be suitable > > people to help out here? > > There was quite a bit of review of the cover letter from Michal and > David, but you're right the details not so much as of yet. I'd like to > call out other people where I can reciprocate with some review of my > own. Oscar's altmap work looks like a good candidate for that. I'm also hoping Jeff can give a tested-by for the customer scenarios that fall over with the current implementation.