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b=Fdto37NsxkGWyHA+unNKY45cJTXS6k+L6e6X5/wGfyX+2C/j55hVVbxiT7RzRrR47b1P8kxLXPrFq8y6qgq8K3fPfU4Z/y718PrvodjBmV/aaJMrj6KkH5vyP05WXVXvoMbQ2RNWa4YG+Lmffb1xfhSQrU5JITsDjqJwPp9sWBE= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R841e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037009110;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=18;SR=0;TI=SMTPD_---0XB3ciWe_1789529039; Received: from 30.74.144.115(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0XB3ciWe_1789529039 cluster:ay36) by smtp.aliyun-inc.com; Wed, 16 Sep 2026 11:24:00 +0800 Message-ID: <7afc2108-710d-4f54-9472-6b9f156ce945@linux.alibaba.com> Date: Wed, 16 Sep 2026 11:23:59 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/mglru: restore accidentally removed seq < max_seq check To: "Barry Song (Xiaomi)" , akpm@linux-foundation.org Cc: axelrasmussen@google.com, baoquan.he@linux.dev, david@kernel.org, hannes@cmpxchg.org, kasong@tencent.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ljs@kernel.org, mhocko@kernel.org, qi.zheng@linux.dev, ridong.chen@linux.dev, shakeel.butt@linux.dev, weixugc@google.com, yuanchu@google.com, yuzhao@google.com, Chuanhua Han References: <20260915101556.50467-1-baohua@kernel.org> From: Baolin Wang In-Reply-To: <20260915101556.50467-1-baohua@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 62D4A180005 X-Stat-Signature: 3kkuebebhifykf54dmmba9gxjbs8xpgk X-HE-Tag: 1789529045-602164 X-HE-Meta: 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 DI6VfOtN 9VJ9sriIMY/fyPlVbqnTONrd7n8KL8yqKSwyAI+hPLTyRosnW7wkYSbNqeLMUU6TcsWxfssCXcw+6+JJrSmGDkOSBrDjU84gqWpGk7FZMlNjj40XwWSTCpeSqyMJM+irfQxYR0uArT4TdQNc1D+oQKBtWdap9MIeyZnqP3FdlPLC/l97KFTEtipbobWVSs+tuQk1qdTczRMEMiyPwN+sXvZexRH+9a9ssKoUXaZ956jQOtedsUf4tDvsHpQJ1pF4k1HXcuQtwddhKaDdzemPuDVekaI1wu+56MHnrKdLoQnRdGjwNWajv8dBuMtUYssq8kAeJItYH0JrT4uKHuK43wXNNdjO+tbO33x1pmajOLkmMN4IPXKR89Tt47wTsmaQXG+9Cs8b+etHe+5uXc9UulrhHD3SSpcZMXMFLTilJgZVD3DY= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/15/26 6:15 PM, Barry Song (Xiaomi) wrote: > Since commit 798c0330c2ca ("mm/mglru: rework aging feedback"), > the following sanity check was accidentally removed: > if (seq < max_seq) > return 0; > > That means we can perform aging for any value less than or equal to > max_gen_nr. > > This has been inconsistent with > Documentation/admin-guide/mm/multigen_lru.rst, which states: > > Users can write the following command to ``lru_gen`` to create a new > generation ``max_gen_nr+1``: > > ``+ memcg_id node_id max_gen_nr [can_swap [force_scan]]`` > > The correct semantics are that writing a value smaller than > max_gen_nr should return 0, since the requested generation already > exists. > > Fixes: 798c0330c2ca ("mm/mglru: rework aging feedback") > Reported-by: Chuanhua Han > Signed-off-by: Barry Song (Xiaomi) > --- LGTM. Reviewed-by: Baolin Wang