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Date:   Thu, 27 Sep 2018 13:20:41 +0200
From:   Michal Hocko <mhocko@kernel.org>
To:     Dan Williams <dan.j.williams@intel.com>
Cc:     alexander.h.duyck@linux.intel.com, Linux MM <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-nvdimm <linux-nvdimm@lists.01.org>,
        Pasha Tatashin <pavel.tatashin@microsoft.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        =?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>,
        rppt@linux.vnet.ibm.com, Logan Gunthorpe <logang@deltatee.com>,
        Ingo Molnar <mingo@kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the
 point where we init pgmap
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On Wed 26-09-18 11:52:56, Dan Williams wrote:
[...]
> Could we push the hotplug lock deeper to the places that actually need
> it? What I found with my initial investigation is that we don't even
> need the hotplug lock for the vmemmap initialization with this patch
> [1].

Yes, the scope of the hotplug lock should be evaluated and _documented_.
Then we can build on top.
-- 
Michal Hocko
SUSE Labs