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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <20230209102954.528942-1-dhowells@redhat.com> <20230209102954.528942-2-dhowells@redhat.com> To: Matthew Wilcox Cc: dhowells@redhat.com, Jens Axboe , Al Viro , Christoph Hellwig , Jan Kara , Jeff Layton , David Hildenbrand , Jason Gunthorpe , Logan Gunthorpe , Hillf Danton , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzbot+a440341a59e3b7142895@syzkaller.appspotmail.com, Christoph Hellwig , John Hubbard Subject: Re: [PATCH v13 01/12] splice: Fix O_DIRECT file read splice to avoid reversion of ITER_PIPE MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <757357.1675955219.1@warthog.procyon.org.uk> Date: Thu, 09 Feb 2023 15:06:59 +0000 Message-ID: <757358.1675955219@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 X-Stat-Signature: 43papzgtbcxrbrghb8dw5r1jqok4ruze X-Rspam-User: X-Rspamd-Queue-Id: 07EAA14003B X-Rspamd-Server: rspam06 X-HE-Tag: 1675955229-625035 X-HE-Meta: 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 QS8Wg05u fxDCV8aNC8hlkYYY3ZpyN9mhL1t3Bl0B+ZuFMaUmsiJDvN6iFid9SpqwkttSPhukV9v0FojDAycHkVlkf2zaL8yTfr68DWFnSkKrQwN6QTcYbnUYecivDxbSLylllxhvao+bMwEguF1fH724zqmtn4d+eMC2oJrJdIEVre5Mc7roxoLlE5FelsbelcU5ixIhbt5rFnJpFCNY2EoRTFPEydBRa2vCFddL+WHlBCKSZHEpMZsaGo+Xo9CX+JdjmPxRbpEp6NfdT10xBSjI+Db8ci7DM62qH0ps+pucX42GrDrmAZxDdSZw6AOrurXgxGRr+Q14onpUZwA2zPD/b5E473c+XmjqjKSwZqjfCFtvm+Zjf/lOorI2EkKJG3w== 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: Matthew Wilcox wrote: > On Thu, Feb 09, 2023 at 10:29:43AM +0000, David Howells wrote: > > + npages = alloc_pages_bulk_list(GFP_USER, npages, &pages); > > Please don't use alloc_pages_bulk_list(). If nobody uses it, it can go > away again soon. Does alloc_pages_bulk_array() work for you? It's > faster. Sure. > > + /* Free any pages that didn't get touched at all. */ > > + for (; reclaim >= PAGE_SIZE; reclaim -= PAGE_SIZE) > > + __free_page(bv[--npages].bv_page); > > If you have that array, you can then use release_pages() to free > them, which will be faster. Um. I would normally overlay the array on end of the bvec[] so that I could save on an allocation (I have to fill in the bvec[] anyway) - which means I wouldn't still have the array at release time. But in this case I can make an exception, though I would've thought that the expectation would be that all the requested data would be fetched. David