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dmarc=pass (policy=none) header.from=linux.alibaba.com; spf=pass (imf26.hostedemail.com: domain of hsiangkao@linux.alibaba.com designates 115.124.30.98 as permitted sender) smtp.mailfrom=hsiangkao@linux.alibaba.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1763820562; 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=3ZDjsY2sg6rvsyUvNLcAYz1go/aL8BSTJ+KSEmWdUmM=; b=4jM7azvYT1egKFm5O38nesm7gz8DmdyO7jxtR5QOp5M60pqwDyvU32+zNUwaVQ4KKoVclM Znp5gp82wpkqjiLZuopd9dHuNgFk66h0zQIurCcn3rfiK8f8QNqhlUQ1aVdM6urC4Y0lce KgCZkJ0pcjh3aZQZrjthUMVrG6+/VE4= 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 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 X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: A35B614000A X-Stat-Signature: aqzyh1mdea9daw8uo8t66usncu9e1jr9 X-HE-Tag: 1763820561-728813 X-HE-Meta: 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 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: List-Subscribe: List-Unsubscribe: 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