From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 44304606A32C for ; Thu, 5 Nov 2026 07:00:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=gu3dXD8o Received: by kanga.kvack.org (Postfix) id 635846B05B7; Thu, 5 Nov 2026 02:00:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 60DDB6B05B8; Thu, 5 Nov 2026 02:00:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5238C6B05B9; Thu, 5 Nov 2026 02:00:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 2FD036B05B7 for ; Thu, 5 Nov 2026 02:00:11 -0500 (EST) Received: from smtpin06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 8CFC2A0975 for ; Thu, 5 Nov 2026 07:00:09 +0000 (UTC) X-FDA: 85400166138.06.C36B00E Received: from mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) by imf08.hostedemail.com (Postfix) with ESMTP id 8ADDD160007 for ; Thu, 5 Nov 2026 07:00:07 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=gu3dXD8o; spf=pass (imf08.hostedemail.com: domain of mengmeng.zhao@linux.dev designates 91.218.175.188 as permitted sender) smtp.mailfrom=mengmeng.zhao@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793862007; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=0wrzHtFxjFXd7iU05CW3/ydQ7QCAtEugjeoklBp7xpE=; b=emvA0ckdXlyrDg6WV+XSM4JBdtdPa47/4ptpgnxUYZwLe9VjPkFT8LAKzhXraDs7yCzRPY wRL2fh7P/1z2QdkfG7PtfWbgauU+DLft49v/sQVARc2MBskvAMWT+g/ASPqaZwicOrwS4d 8ePp8oOYhRvfRtPEIpKeWc14UwqIAfA= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793862007; b=5LvTRBIPLW4Zg+so7R94nYy1v8oIRrNUcJZ7KS5S9vA4Nkv9QZymTMAEev/r2v3n8fhdLp e7iSiwTQ6Wcti8dSRKLRAC06o3FPzSNFEEm1qXG5t4TcVNgcb1XyD2yllhMJmIG6GQyAgY pMHBaFFJzy9Ui9cmqo1er0zaee/0fPM= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=gu3dXD8o; spf=pass (imf08.hostedemail.com: domain of mengmeng.zhao@linux.dev designates 91.218.175.188 as permitted sender) smtp.mailfrom=mengmeng.zhao@linux.dev; dmarc=pass (policy=none) header.from=linux.dev X-Envelope-To: linux-mm@kvack.org DKIM-Signature: a=rsa-sha256; bh=ax+wsuHoy6H96hgXiHuF6MzNsH6ADwaKJZJ1/7kMLiA=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793862006; v=1; x=1794466806; b=gu3dXD8ovEhih0rAWmev6W2AOFR/IDaEehfUUFgeNq3wirBmvDlKHAqm5p/Tz+SA1BiOQuOG qCkwAa3XXnNoqIpcTagxmPi0o24Eif2ZmOzorQBk0pIqEJNSX3rILgB0r5bQ7BLrRzLo2c1K3q2 2yZoCEZ1tjhFvPYpMUYTiwmY= X-Envelope-To: linux-mm@kvack.org Received: by smtp.migadu.com with ESMTPS id 96e1fbcbd6d57c1a; Thu, 05 Nov 2026 07:00:05 +0000 X-Mizu-Trace-ID: 96e1fbcbd6d57c1a X-Migadu-Flow: FLOW_OUT From: Mengmeng Zhao To: Jens Axboe , Dan Williams , Matthew Wilcox , Jan Kara , Alexander Viro , Christian Brauner , tytso@mit.edu, Andreas Dilger , Baokun Li , Ojaswin Mujoo , "Ritesh Harjani (IBM)" , Zhang Yi , "Darrick J. Wong" , Andrew Morton , asml.silence@gmail.com, hch@lst.de, Anuj Gupta Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, Li Wang Subject: [RFC 4/6] iomap: refuse dmabuf iterators in iomap_file_buffered_write() Date: Thu, 5 Nov 2026 14:58:45 +0800 Message-ID: <20261105065847.196540-5-mengmeng.zhao@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261105065847.196540-1-mengmeng.zhao@linux.dev> References: <20261105065847.196540-1-mengmeng.zhao@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam06 X-Stat-Signature: fjyofwa9hjxa4raaezz9sfh4z1i9zqdk X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Queue-Id: 8ADDD160007 X-Rspam-User: X-HE-Tag: 1793862007-839397 X-HE-Meta: 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 9CSsFDHj vpHGaQx5hUwGnSAD/q9Yyl2t4NFNDxEz9bCYeipNGeO6q7x6gmeFkSBMIgVsCYDvF3uvHaEfcZ1KTiIGpTc61zEdHQrkx0TqLc/4tfQA02eUVqnXvsA52hSa2hoFtEpl3qM3R1N3mjiTQC78is/Tj82ynZ8dTQq3hoefzOA3iYyFj34gUvPGq1jjn2E7+udc7wUzL5neN93MZTI3q3bvc0spiW1ti3IDfk93/2KCqgJNMuzOuzDdYZImNZ0/6wbylTFA/ic/DDwMeDaw8qKcjhjY+wh4oc+bRok9DQaOhvn2Z+/KqBAbmykSktF+rc5tBY08SQjWy6JLbN2eEkgqJMkCjnYrGoMz4lxtL Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 From: Mengmeng Zhao A buffered write copies through the CPU linear address, which a device mapping cannot provide. fault_in_iov_iter_readable() treats a dmabuf iterator as always readable, so the copy fails with a WARN_ON_ONCE from iterate_and_advance2() and iomap_write_iter() retries the unchanged remainder forever. Refuse the iterator at the entry with -EOPNOTSUPP, as generic_perform_write() and the generic read paths already do, so that every generic buffered copy helper turns the iterator away before touching the page cache. Signed-off-by: Mengmeng Zhao Signed-off-by: Li Wang --- fs/iomap/buffered-io.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 0a5ebfda90f1..3f56bd225e8c 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -1304,6 +1304,13 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i, }; ssize_t ret; + /* + * A buffered write copies through the CPU linear address, which a + * device mapping cannot provide. + */ + if (iov_iter_is_dmabuf_map(i)) + return -EOPNOTSUPP; + if (iocb->ki_flags & IOCB_NOWAIT) iter.flags |= IOMAP_NOWAIT; if (iocb->ki_flags & IOCB_DONTCACHE) -- 2.43.0