From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4FD2BC7618B for ; Tue, 14 Mar 2023 21:50:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CB8C56B0071; Tue, 14 Mar 2023 17:50:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C68EE8E0001; Tue, 14 Mar 2023 17:50:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B09456B0078; Tue, 14 Mar 2023 17:50:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 9C7696B0071 for ; Tue, 14 Mar 2023 17:50:26 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 111E7AB37E for ; Tue, 14 Mar 2023 21:50:26 +0000 (UTC) X-FDA: 80568848052.02.7806FAB Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf12.hostedemail.com (Postfix) with ESMTP id 31B784001B for ; Tue, 14 Mar 2023 21:50:23 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=gdFQS1mB; spf=pass (imf12.hostedemail.com: domain of dhowells@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=dhowells@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1678830624; a=rsa-sha256; cv=none; b=uJp6aK17W6Beuvgh0683A3QLoRykMzLIyEt6dKPV2c5F1ZQMFHy7HU9/9K2TXmiGwW5h8B IDS+Nc9+ja9OL89fSTRKqnRGwSbx9j8GChf8ONzDLhUO9a734GiWY2MvpJfLjvBAe1oWws zZRKnWlncg+Ae8tfstgJtZs8v/DHAnc= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=gdFQS1mB; spf=pass (imf12.hostedemail.com: domain of dhowells@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=dhowells@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1678830624; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=KWBL8j9Kw5UJa5rIZGzcpgA4OkzAlidgj6Myi5kTuW4=; b=7Enuebw6VCBakP5APD41aenIP5/5o+FWRQep66CEPGlKhEqpOUqPnv5CxcaFPFMa1JxXYp NYKileimo6e0OKGvyLUpMV7li7sxJdrjAUCwDnLU11sZ6hdfTiZgrIjwuPG9KPX4XVNAwH jNmQDC/EmnzL/TAXJlXhjwJ2DoR01kU= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1678830623; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KWBL8j9Kw5UJa5rIZGzcpgA4OkzAlidgj6Myi5kTuW4=; b=gdFQS1mBZx/KzxzYhg9EmTqiz4Z9uGLVJqfPoqOjE7l/UD6xLlZ1F/Q/krYGYVpahIg2A0 MUIrWPfCblMIrWIQU+c6KkbDTLLdkbXG8u7Ryh31SAA/L0h0FTdAMOrYAsHVuMz6wcTqMF 34OYnUEdUVt8K8kXUkqqy6chO9+DJy4= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-480-URV1ga8lPOq_q_b6t_9rpg-1; Tue, 14 Mar 2023 17:50:16 -0400 X-MC-Unique: URV1ga8lPOq_q_b6t_9rpg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7DB3385A588; Tue, 14 Mar 2023 21:50:15 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id DB3572166B26; Tue, 14 Mar 2023 21:50:12 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <20230308165251.2078898-1-dhowells@redhat.com> <20230308165251.2078898-4-dhowells@redhat.com> <3761465.1678818404@warthog.procyon.org.uk> To: Linus Torvalds Cc: dhowells@redhat.com, Matthew Wilcox , 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, Daniel Golle , Guenter Roeck , Christoph Hellwig , John Hubbard , Hugh Dickins Subject: Re: [PATCH v17 03/14] shmem: Implement splice-read MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <3826545.1678830612.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Tue, 14 Mar 2023 21:50:12 +0000 Message-ID: <3826546.1678830612@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 X-Rspam-User: X-Rspamd-Queue-Id: 31B784001B X-Rspamd-Server: rspam01 X-Stat-Signature: dc43sm74xwgq17k1qgc87qsum3a6osx4 X-HE-Tag: 1678830623-47214 X-HE-Meta: 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 3ULasbji 3rA/HPZKNXp3LHf4gvvusbbNz2BIVnktvXlap5f1ok4c1sN0K+AIA+enlzBM1HNFa0x6aNjhwtaZAc21sEg+q+KNneqZGuoaoX09tITWgW1AOcc27iIpqCs0C5tL3FVLYtLAAk2qggwEE72VON1uflA0umgn4V9+qlaQ2UGcnmv/t3aJM8jLjvSQQ7U6mULZATgQktCwuOcfLm5LIB157Zi/kS4l1vklhZU99YJ09E2ZaL+4= 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: Linus Torvalds wrote: > But please at least stop doing the > = > get_page(buf->page); > = > on the zero-page (which includes using no-op .get and .put functions > in zero_pipe_buf_ops(). I'll make the attached change. It seems to work. David --- diff --git a/mm/shmem.c b/mm/shmem.c index 3cbec1d56112..d9b60ab556fe 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2719,6 +2719,17 @@ static ssize_t shmem_file_read_iter(struct kiocb *i= ocb, struct iov_iter *to) return retval ? retval : error; } = +static bool zero_pipe_buf_get(struct pipe_inode_info *pipe, + struct pipe_buffer *buf) +{ + return true; +} + +static void zero_pipe_buf_release(struct pipe_inode_info *pipe, + struct pipe_buffer *buf) +{ +} + static bool zero_pipe_buf_try_steal(struct pipe_inode_info *pipe, struct pipe_buffer *buf) { @@ -2726,9 +2737,9 @@ static bool zero_pipe_buf_try_steal(struct pipe_inod= e_info *pipe, } = static const struct pipe_buf_operations zero_pipe_buf_ops =3D { - .release =3D generic_pipe_buf_release, + .release =3D zero_pipe_buf_release, .try_steal =3D zero_pipe_buf_try_steal, - .get =3D generic_pipe_buf_get, + .get =3D zero_pipe_buf_get, }; = static size_t splice_zeropage_into_pipe(struct pipe_inode_info *pipe,