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Sun, 23 Nov 2025 09:23:33 +0800 Message-ID: Date: Sun, 23 Nov 2025 09:23:31 +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> <2c6906d1-132e-401f-830f-ae771fe836c5@linux.alibaba.com> From: Gao Xiang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspam-User: X-Rspamd-Queue-Id: 035334000A X-Stat-Signature: jtcw4darma3p1gyju6njym8c1otmu9oq X-HE-Tag: 1763861017-273602 X-HE-Meta: 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 v3sJ3zke 0GpMwfjOtnRmCKxpxUHHzldr/HuK16QW0ZNMDfOpxuC1SDNgrYHGGubpXluVgT5VCglr4rJCEuONIPVYMenbU6W2hwWWW6QSmbTXBq200U7xhucoH91MkuyhXuoMVgwk9n1p9e1ZR/I5K4snnSVMuNBzNSt4gx6AedruCQoXLT9wWQTKHnO6mcXebkKd1vHZzdkUYcWBH0PKpPIE9o9jY8hd0JR3oQuv1U/JA25kpen1TdwHiRBXzZO5+eNGfzwhiHdC4NNInN4yrw/iEe76b/qJSmi9XCBXbcq2FdRkEr72rqTQrGcgDjxSVw2NsuHcfA1cArZJAlEEmNKkVe00HgbjgWKROndAy/GAM 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 2025/11/23 08:08, Sergey Senozhatsky wrote: > On (25/11/22 22:09), Gao Xiang wrote: >>> 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? > > We take pages of data from zram0 and write them straight to > the backing device. Those writes don't go through vfs/fs so > fs on the backing device will simply be corrupted, as far as > I can tell. This is not intendant use case for zram writeback. I'm pretty sure you don't understand what I meant. I won't reply this anymore, good luck. Thanks, Gao Xiang