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From:   Dan Williams <dan.j.williams@intel.com>
Date:   Tue, 18 Feb 2020 19:25:15 -0800
Message-ID: <CAPcyv4iZCnSpypshYpXCL35yT4KZfgXqDqS8cFDGpXC-A72Utg@mail.gmail.com>
Subject: Re: [PATCH v2 RESEND] mm/sparsemem: pfn_to_page is not valid yet on SPARSEMEM
To:     Baoquan He <bhe@redhat.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux MM <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Wei Yang <richardw.yang@linux.intel.com>,
        David Hildenbrand <david@redhat.com>,
        Oscar Salvador <osalvador@suse.de>,
        Michal Hocko <mhocko@suse.com>
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On Tue, Feb 18, 2020 at 7:05 PM Baoquan He <bhe@redhat.com> wrote:
>
> From: Wei Yang <richardw.yang@linux.intel.com>
>
> When we use SPARSEMEM instead of SPARSEMEM_VMEMMAP, pfn_to_page()
> doesn't work before sparse_init_one_section() is called. This leads to a
> crash when hotplug memory:

I'd also add:

"On x86 the impact is limited to x86_32 builds, or x86_64
configurations that override the default setting for
SPARSEMEM_VMEMMAP".

Other than that:

Reviewed-by: Dan Williams <dan.j.williams@intel.com>