From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.135 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794192871; b=ZUnugwgvPTtg0N9upLZV+mZ/v6OplMcTrMVC1z1hUK+is6MGiy2aS8aHGYzxHZl/Wv74 wzK2PzMnVpMIeoPt1ZzADLXbHFsAqrbefBfjIqGxXw4OtUHtDRL8s5SY3kH96Z/wJd8Ln aZCrQ4HPIWXJfwFhhqvBiHeKWTeMOf0F5Z8nLx+bYo+VpywJoU4Q04InAKhX07wDtSoOv Bhvd/GY4iGoiCxEWhOks9si627Bw2QYfwkFUwrZHv+WFwhXE3tzOm7BpClzvgPyd4WGO5 LIFBaqI9k7QLDoxGrBm0ANCnVSqaovHprRXbJDoFyY4Umm/5P5w4+iXT5jHfoLZUxdA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794192871; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:From:In-Reply-To:Content-Type: Content-Transfer-Encoding; bh=eoxX5hhnrVdnCsiEYxw4rUS1B0+rsEN339m2Nai3htg=; b=3eOmtaXd0FrX/qxBsCyyQPsAkGG0GLlpVXjFz+52niMQ+DlePg3ovVSEI4FexGw9cFlu tW2eu4nXNZLGWM2NtjopkraBYtp8+VFOAVx/uozm/32faHxn2SgxSkxy6gdnB/xkwYaVA fNni6vLGF5eTOCeodUNmdsFOYD+Ip8ABvdwbBNHdXXhA2LTVB+4PiaoIsq8IOz0pAgx03 vQKKqkj1M1QPyixqok2c5wYTasZOK2CXqyRmLrTN3QqouXFx1pXyuscWbQMUl2MYzCunb 1Iw9GEYSi5Vnx10tFx8XBosupXiU1OEjHaNAi8/5ByXw59B0RqcamjMmXbIUsjIAweQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=tN54d4fE; arc=none smtp.remote-ip=95.215.58.135 Received: from mta1.migadu.com (out-135.mta1.migadu.com [95.215.58.135]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CDD24606A321 for ; Mon, 9 Nov 2026 02:54:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org CDD24606A321 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev 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=tN54d4fE X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=8GZA7yXccoOl25ncF5WoFStP/OWge7+wGkdg+7Q22+4=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794192869; v=1; x=1794797669; b=tN54d4fELbTw1iziAe++lO07fZ5SAh4ue1naK2/9LPEFWsB9OLEZ7IIGwvMwJvNf7ENjDX9l QF+x5znsrYZqBLXzHYLOEerlPhB46/CjWVcI55sfgyCGnVuArQb6b6zkWJJxnh0Q7RS+EamCd8D JxPzlZh1L1SF3JmB2gcgkYPc= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 197dc3b85a73d5c0; Mon, 09 Nov 2026 02:54:28 +0000 X-Mizu-Trace-ID: 197dc3b85a73d5c0 X-Migadu-Flow: FLOW_OUT Message-ID: Date: Mon, 9 Nov 2026 10:54:14 +0800 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC 2/6] mm/filemap: refuse dmabuf iterators in the generic read/write copy paths To: Christoph Hellwig Cc: 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, Anuj Gupta , 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 References: <20261105065847.196540-1-mengmeng.zhao@linux.dev> <20261105065847.196540-3-mengmeng.zhao@linux.dev> <20261106104205.GB5668@lst.de> From: Mengmeng Zhao In-Reply-To: <20261106104205.GB5668@lst.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/6/26 18:42, Christoph Hellwig wrote: > On Thu, Nov 05, 2026 at 02:58:43PM +0800, Mengmeng Zhao wrote: >> From: Mengmeng Zhao >> >> The generic copy helpers cannot touch device memory. > > Which generic copy helpers? This doesn't seem to touch copy_file_range > at all. > Sorry for the inaccuracy, it refers to the buffered io patch in generic_file_read_iter() and __generic_file_write_uter(). >> Refuse a >> dmabuf iterator in generic_perform_write() and the filemap_read() >> fallback while keeping any direct-I/O progress, and report a busy >> folio from generic_file_direct_write() as -EAGAIN instead of asking >> for the buffered fallback such an iterator cannot take. > > I suspect the fallback code in the callers might be a better stop > for this. > Ok, I will put it in the callers side.