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From:   David Hildenbrand <david@redhat.com>
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Subject: Re: [PATCH v6 2/8] mm,memory_hotplug: Relax fully spanned sections check
Date:   Tue, 6 Apr 2021 22:43:01 +0200
Message-Id: <59A04B1D-08D6-4E71-A382-F5503A6E0AF7@redhat.com>
References: <df9bdb5157d6ad2f4a922d396ddf0c07@suse.de>
Cc:     David Hildenbrand <david@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@kernel.org>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Pavel Tatashin <pasha.tatashin@soleen.com>,
        Vlastimil Babka <vbabka@suse.cz>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
In-Reply-To: <df9bdb5157d6ad2f4a922d396ddf0c07@suse.de>
To:     Oscar Salvador <osalvador@suse.de>
Precedence: bulk


> Am 06.04.2021 um 18:34 schrieb Oscar Salvador <osalvador@suse.de>:
>=20
> =EF=BB=BFOn 2021-04-06 17:32, David Hildenbrand wrote:
>> I'd only relax start_pfn. That way the function is pretty much
>> impossible to abuse for sub-section onlining/offlining.
>> if (WARN_ON_ONCE(!nr_pages ||
>>         !IS_ALIGNED(start_pfn, pageblock_nr_pages))
>>         !IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION)))
>=20
> But this is not going to work.
> When using memmap_on_memory, the nr of pages that online_pages() and offli=
ne_pages() get might be less than PAGES_PER_SECTION, so this check will alwa=
ys blow us up.

But not end_pfn as given in my version or what am I missing?


> --=20
> Oscar Salvador
> SUSE L3
>=20