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From:   Jeff Moyer <jmoyer@redhat.com>
To:     Michal Hocko <mhocko@kernel.org>
Cc:     Dan Williams <dan.j.williams@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        =?utf-8?B?SsOpcsO0bWU=?= Glisse <jglisse@redhat.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        Toshi Kani <toshi.kani@hpe.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        stable <stable@vger.kernel.org>, Linux MM <linux-mm@kvack.org>,
        linux-nvdimm <linux-nvdimm@lists.01.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 00/10] mm: Sub-section memory hotplug support
References: <155327387405.225273.9325594075351253804.stgit@dwillia2-desk3.amr.corp.intel.com>
        <20190322180532.GM32418@dhcp22.suse.cz>
        <CAPcyv4gBGNP95APYaBcsocEa50tQj9b5h__83vgngjq3ouGX_Q@mail.gmail.com>
        <20190325101945.GD9924@dhcp22.suse.cz>
Date:   Mon, 25 Mar 2019 10:28:00 -0400
In-Reply-To: <20190325101945.GD9924@dhcp22.suse.cz> (Michal Hocko's message of
        "Mon, 25 Mar 2019 11:19:45 +0100")
Message-ID: <x494l7rdo5r.fsf@segfault.boston.devel.redhat.com>
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Michal Hocko <mhocko@kernel.org> writes:

>> > and I would like to know that you are
>> > not just shifting the problem to a smaller unit and a new/creative HW
>> > will force us to go even more complicated.
>> 
>> HW will not do this to us. It's software that has the problem.
>> Namespace creation is unnecessarily constrained to 128MB alignment.
>
> And why is that a problem? A lack of documentation that this is a
> requirement? Something will not work with a larger alignment? Someting
> else?

See this email for one user-visible problem:
  https://lore.kernel.org/lkml/x49imxbx22d.fsf@segfault.boston.devel.redhat.com/

Cheers,
Jeff