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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rpUg1-000000045du-1rrn; Wed, 27 Mar 2024 14:54:53 +0000 Date: Wed, 27 Mar 2024 14:54:53 +0000 From: Matthew Wilcox To: Zi Yan Cc: Kefeng Wang , Andrew Morton , Miaohe Lin , Naoya Horiguchi , David Hildenbrand , Oscar Salvador , Hugh Dickins , Jonathan Corbet , linux-mm@kvack.org, linux-doc@vger.kernel.org, Baolin Wang Subject: Re: [PATCH 2/6] mm: memory_hotplug: use more folio in do_migrate_range() Message-ID: References: <20240327141034.3712697-1-wangkefeng.wang@huawei.com> <20240327141034.3712697-3-wangkefeng.wang@huawei.com> <01BB19DC-3807-4954-A04A-55518301B6BA@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <01BB19DC-3807-4954-A04A-55518301B6BA@nvidia.com> X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 74659120024 X-Stat-Signature: 6cq9rwfw73ipunyc7nsgktfrpfyz6fuw X-HE-Tag: 1711551309-448052 X-HE-Meta: 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 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: List-Subscribe: List-Unsubscribe: On Wed, Mar 27, 2024 at 10:45:42AM -0400, Zi Yan wrote: > > for (pfn = start_pfn; pfn < end_pfn; pfn++) { > > - struct folio *folio; > > + struct page *page, *head; > > You could get rid of head too. It is only used to calculate next pfn, > so pfn = folio_to_pfn(folio) + folio_nr_pages(folio) - 1 would work. > > And the PageHuge(page) and PageTransHuge(page) can be simplified, since > their pfn calculations are the same. Something like: > > if (folio_test_large(folio)) { > pfn = folio_to_pfn(folio) + folio_nr_pages(folio) - 1; > if (folio_test_hugetlb(folio)) { > isolate_hugetlb(folio, &source); > continue; > } > } How much of this is safe without a refcount on the folio?