From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-113.freemail.mail.aliyun.com (out30-113.freemail.mail.aliyun.com [115.124.30.113]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0405C1C5D59; Sat, 22 Nov 2025 14:09:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.113 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763820563; cv=none; b=pnOPHwotEsYpbaJ3WT9tqMGRZPHJv2MN/hpBWCDj0ZGYy3/YSTKKmLH5vMEehiwanlNyfajSmMDlFBHLXZC5HB0yvFnz7YZcTC2YPRkHrxSctT5rFOLojydYaImCuTDqzZBKUlqaWz5P393H2WU8UQaD23ZS2i19sG10q2/8CqE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763820563; c=relaxed/simple; bh=HqN60t5Kr9L1orycE6I/k9Pk7qJw1ucp1Rc5gEL0cWQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TpdXXjjXCjdVZd2ghoGf4BxiU99PsQwHZGt/xr9aeug1Ve3YANFnxZogMAWd/10X6OGPf57CT2AKS1ZbUk4By7Au9cG/9L+dYHrIuQ198NhgXVHNgvCFsso55KjUVRndiBz/WbWDKnfLhEhW2hwAy9OMd7DIhklMsgjwoc0yHAk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=e4eJ2S/a; arc=none smtp.client-ip=115.124.30.113 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="e4eJ2S/a" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1763820557; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=3ZDjsY2sg6rvsyUvNLcAYz1go/aL8BSTJ+KSEmWdUmM=; b=e4eJ2S/aNNfPW+aDnhFZIZY/nsFKTgLYpbsQqeTQThk+plL2pqPqTNDZMKL66KXgIikZfJD6N+ejHEObQy5IihJoPqBUAFKAevOy5ibaQRIkPs44wudonee0VorqrOSShVZogC4Qa09hlo6Cr4F21yjAiKXC1JkmUfOgdz0uGF4= Received: from 30.170.82.147(mailfrom:hsiangkao@linux.alibaba.com fp:SMTPD_---0Wt4WfL4_1763820555 cluster:ay36) by smtp.aliyun-inc.com; Sat, 22 Nov 2025 22:09:16 +0800 Message-ID: <2c6906d1-132e-401f-830f-ae771fe836c5@linux.alibaba.com> Date: Sat, 22 Nov 2025 22:09:15 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCHv5 0/6] zram: introduce writeback bio batching To: Sergey Senozhatsky Cc: Yuwen Chen , akpm@linux-foundation.org, bgeffon@google.com, licayy@outlook.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, minchan@kernel.org, richardycc@google.com References: <8c596737-95c1-4274-9834-1fe06558b431@linux.alibaba.com> <853796e3-fd44-4fc2-8fd2-5810342a6ebe@linux.alibaba.com> From: Gao Xiang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2025/11/22 21:43, Sergey Senozhatsky wrote: > On (25/11/22 20:24), Gao Xiang wrote: >> zram(ext4) means zram device itself is formated as ext4. >> >>> >>>> zram(ext4) -> backing ext4/btrfs >>> >>> This is not a valid configuration, as far as I'm concerned. >>> Unless I'm missing your point. >> >> Why it's not valid? zram can be used as a regular virtual >> block device, and format with any fs, and mount the zram >> then. > > I thought you were talking about the backing device being > ext4/btrfs. Sorry, I don't have enough context/knowledge > to understand what you're getting at. zram has been doing > writeback for ages, I really don't know what you mean by > "to act like this". I mean, if zram is formatted as ext4, and then mount it; and then there is a backing file which is also in another ext4, you'd need a workqueue to do writeback I/Os (or needs a loop device to transit), was that the original question raised by Yuwen? If it's backed by a physical device rather than a file in a filesystem, such potential problem doesn't exist. Thanks, Gao Xiang