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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20230125210657.2335748-3-dhowells@redhat.com> References: <20230125210657.2335748-3-dhowells@redhat.com> <20230125210657.2335748-1-dhowells@redhat.com> Cc: dhowells@redhat.com, Al Viro , Christoph Hellwig , Matthew Wilcox , Jens Axboe , Jan Kara , Jeff Layton , David Hildenbrand , Jason Gunthorpe , Logan Gunthorpe , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Hellwig , John Hubbard Subject: Re: [PATCH v10 2/8] iov_iter: Add a function to extract a page list from an iterator MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2642249.1674733015.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Thu, 26 Jan 2023 11:36:55 +0000 Message-ID: <2642250.1674733015@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 8CD7B4001F X-Stat-Signature: ffuq1e9utr4qij3go8o43g8iasiusx5m X-HE-Tag: 1674733024-280499 X-HE-Meta: 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 vsS3F4h0 qNExbCvp3dKTdYc+C1nZs81svkl2YHl2wYvlczObUbt8QEkC1F+gzalqiQN7tXRQpmN9ks1D0LAgwe6SSyrgZFwegl6utCaUEPoX46XRZvi5l2AySMUDjAZNXUKR4vHq7FAk8kZ1bJ6gtZoRRabWEQnqpznH48SNjpObo1NuyKhhyOODJQulVXC2FPt8AxJ/xhX3NiltTj7W3OQTDoMgC5BE9sbrCdGtp/nDkThzn6lsOafzxhz2U7HGSJa0kY484WITB6680bbEnSHHcLlPccjpyt3KonQC6VqaB0en5S6rGoIqwk+TE/HGevpXftisQKKNiafRpj4NLaq45vbHubF4whA== 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: iov_iter_extract_kvec_pages() isn't quite right. The problem is that ther= e's not currently any path by which it can be tested, as currently iov_iter_get_pages*() balk at it, but I managed to do that by piggybacking some testing code on my cifs patches. The attached change fixes the problem. David --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -2080,9 +2080,9 @@ static ssize_t iov_iter_extract_kvec_pages(struct io= v_iter *i, skip =3D 0; } = - offset =3D skip % PAGE_SIZE; + kaddr =3D i->kvec->iov_base + skip; + offset =3D (unsigned long)kaddr & ~PAGE_MASK; *offset0 =3D offset; - kaddr =3D i->kvec->iov_base; = maxpages =3D want_pages_array(pages, maxsize, offset, maxpages); if (!maxpages)