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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rf4Pw-00000003LmO-3QiL; Tue, 27 Feb 2024 20:51:12 +0000 Date: Tue, 27 Feb 2024 20:51:12 +0000 From: Matthew Wilcox To: Jianfeng Wang Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, sidhartha.kumar@oracle.com Subject: Re: [PATCH] mm/cma: convert cma_alloc() to return folio Message-ID: References: <20240227181338.59932-1-jianfeng.w.wang@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 31FD540005 X-Stat-Signature: t3dyfpjyhxhrhd4g1i5wkhjacywn1et5 X-HE-Tag: 1709067076-444106 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 Tue, Feb 27, 2024 at 11:26:02AM -0800, Jianfeng Wang wrote: > > > On 2/27/24 11:00 AM, Matthew Wilcox wrote: > > On Tue, Feb 27, 2024 at 10:13:38AM -0800, Jianfeng Wang wrote: > >> Change cma_alloc() to return struct folio. This further increases the > >> usage of folios in mm/hugetlb. > > > > I love the idea, but I don't think this works. The memory returned > > from cma_alloc() isn't set up to be a folio, is it? That is, it > > doesn't have compound_head initialised so that page_folio() on > > consecutive pages will return the same pointer. > > Thanks for review. > cma_alloc() returns an array of order-0 pages. So, this commit makes > cma_alloc() return an array of folios (each an order-0 page) rather > than a compound page. Functions that use cma_alloc() do not expect > a compound page as well. No, this is not the way.