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Miller" , Eric Dumazet , Paolo Abeni , Willem de Bruijn , David Ahern , Matthew Wilcox , Jens Axboe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Tom Herbert , Tom Herbert Subject: Re: [PATCH net-next 3/4] kcm: Support MSG_SPLICE_PAGES Message-ID: <20230526201202.1cd35fe9@kernel.org> In-Reply-To: <20230524144923.3623536-4-dhowells@redhat.com> References: <20230524144923.3623536-1-dhowells@redhat.com> <20230524144923.3623536-4-dhowells@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: C386E140006 X-Rspam-User: X-Stat-Signature: xhpr4y669ws1j7y863it8n1g7n4gmj47 X-Rspamd-Server: rspam01 X-HE-Tag: 1685157125-926515 X-HE-Meta: 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 B7XtXp+r zz8idBhTxgB4Os1PJEEjUzHKYau6Hya8duT24pqoFEpET3pKyRXiavz2fai+1Y/FdrBM9S91L5s3+xF7FjJoZAMEvZ3xXwml4/9eA/F2imORV005LXB3z1eXaTzaNugQuo33OeJv6iuJNKHmcM+7PhSymGd3KLqvC7h7skh298nkX95DlW06KWAGB74UeVyeyVrjKy9wONOv7tPkgLXxR4mUMbtemBPSykjJoHXyhc4WOERKh93AiMsmh8/PYxt5cgF6yPJ2r94m1gHumyOJEWaVxHviMzLChk1Lj2qmQe1nmAn2Dt4hhVea7QPNypTQWQU5jkcxXttLBkG7CA7LcrAEv3EdoEm1syUDEyj/RA3++usfAlVEQS5e1u82hDVgPleHXzTAV+jl+lgN1V+48MqBMsq43OcG+zWQ8 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: On Wed, 24 May 2023 15:49:22 +0100 David Howells wrote: > + err = skb_splice_from_iter(skb, &msg->msg_iter, copy, > + sk->sk_allocation); > + if (err < 0) { > + if (err == -EMSGSIZE) > + goto wait_for_memory; > + goto out_error; > + } > should there be a: copy = err; or: copy -= msg_data_left(msg); or some such here? Can we safely assume that skb_splice_from_iter() will copy all or nothing? > - err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb, > - pfrag->page, > - pfrag->offset, > - copy); > - if (err) > - goto out_error; > + skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;