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From: Shakeel Butt To: Richard Chang Cc: Andrew Morton , Kairui Song , Qi Zheng , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Johannes Weiner , David Hildenbrand , Michal Hocko , Lorenzo Stoakes , Suren Baghdasaryan , "T . J . Mercier" , Martin Liu , Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: vmscan: abort proactive reclaim early when freezing Message-ID: References: <20260706081218.3438762-1-richardycc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Stat-Signature: tdc4xckbwsr55fszhke35mfwe5p6y8pe X-Rspamd-Queue-Id: 46B1E1A0005 X-Rspamd-Server: rspam01 X-Rspam-User: X-HE-Tag: 1783525688-686183 X-HE-Meta: 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 Gez7EnLL 8HH6tTzzcg3JDWhlUB9MGeqPx8patCjohK+fNbLAUnxv5PgYyr19hfyuzZyIGV5ezjvmIGlkAmfl4pds+hImbmMku+9Lqj+aE/7ZEvMoN3k/cKMw5Sgr/wu1qJz3tzrXojtlVvN6TuAVpzNeCRGfbgQd5qvS1sB8+UhDrT/wX/kW4h16p17oG0hs6Q2BGQu9dUoOspdE981Jw7+lism/5lWFPctsh94cGmjpTLPupK+y5IDw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jul 08, 2026 at 03:24:15PM +0800, Richard Chang wrote: > On Wed, Jul 8, 2026 at 12:54 PM Shakeel Butt wrote: > > > > What's so special about proactive reclaim? Why the same situation can not happen > > for global or memcg reclaim? > > > > The target batch size of the global/memcg reclaim is typically very > small -- usually SWAP_CLUSTER_MAX (32 pages), allowing the task to > yield or check signals between attempts. > Furthermore, kswapd is a kernel thread designed to be freezable, it > explicitly checks kthread_freezable_should_stop() in the main loop. > In contrast, the target batch size in proactive reclaim is > user-defined and can be extremely large. Without signal checks in the > inner loops, the task may continue scanning and evicting pages for > seconds at a time. Why can't the proactive reclaim use the same batch size as memcg and global reclaim?