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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/vmpressure: remove window size TODO Message-Id: <20260831101636.a714f7171af108d520d4848c@linux-foundation.org> In-Reply-To: <20260831-remove-vmpressure-todo-v1-1-498515e59cdf@kernel.org> References: <20260831-remove-vmpressure-todo-v1-1-498515e59cdf@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 1C40020003 X-Stat-Signature: bsjyx6s5uaoh86tie8e4xpor1hdtt44b X-HE-Tag: 1788196597-553956 X-HE-Meta: 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 7J0UyhTB ZWbf1MVFGc8pupv5me/SjtB3gxfjOTfaG4kg0M7Tgz1t+vS8k4FomIBkLv8O1Z990HOAK2RkmzsXkeYSdKFagmnyblVlxeD5rqsa5A0ZpjzaeK4gfEjouXu+va3yQMNUfoa966e79z049EG09CopnpqT0NsBUn5Jq9gsGFmarVI9zx2Zeo6unGOvPkFleu2Ss5Y4f8H1hna7nhaYMmOfV2qAPPNSXtR8f3tV70WpTQqtG9Q6FrgQs9bUBc/fLep5cG4I+QtzQdS2b7ec= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 31 Aug 2026 14:42:11 +0100 "Lorenzo Stoakes (ARM)" wrote: > There has been a steady stream of patches that have been submitted by > newcomers to core mm 'fixing' this TODO, with all but the original having > very likely been generated by LLMs. > > It appears that TODOs to LLMs are like red rags to a bull. > > In addition, TODOs in code often bitrot and are distracting - those who > understand the code know what could be improved in future. > > Therefore remove the TODO. > > The work required to actually fix this TODO requires somebody who both has > understanding of the code and significant real-world data to back their > changes. > > Such a person doesn't require a TODO prompt to implement this change, so > nothing of value is being lost here. > > ... > > --- a/mm/vmpressure.c > +++ b/mm/vmpressure.c > @@ -30,9 +30,6 @@ > * > * As the vmscan reclaimer logic works with chunks which are multiple of > * SWAP_CLUSTER_MAX, it makes sense to use it for the window size as well. > - * > - * TODO: Make the window size depend on machine size, as we do for vmstat > - * thresholds. Currently we set it to 512 pages (2MB for 4KB pages). > */ > const unsigned long vmpressure_win = SWAP_CLUSTER_MAX * 16; otoh, we could enhance the TODO to explain these considerations. This might result in the LLM warriors submitting more usable work. It would be a strange place to socialize these things but as you said, red rags.