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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , Andrew Morton , Peter Zijlstra , Ingo Molnar , Will Deacon , Boqun Feng , Waiman Long , Suren Baghdasaryan , Vlastimil Babka , Shakeel Butt , Yonghong Song , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , linux-mm@kvack.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH 2/5] mm/khugepaged: scan mm's more efficiently under mmap_lock contention Message-ID: References: <20261103-khugepaged-latency-fix-v1-0-a07ab16ac860@kernel.org> <20261103-khugepaged-latency-fix-v1-2-a07ab16ac860@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 9579320008 X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Stat-Signature: 94ym33k9zwi7pf45hxui1jy3iuk1uqey X-Rspam-User: X-HE-Tag: 1793887326-310818 X-HE-Meta: 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 AYhEye2c Cxp73iswMfRPA35jh3NSvzzo/RglzkxQjGtxQ25UuTgvmbeMHlN1GEjPFbvctn4YOC8HwlD2LxMs9nyErkAwYk1QKsC9RuVTmlqLj/XKvDekpNam+F0hlxFCc+LZlbyVUYj6pymkSO8TFnGsw8ZTmfcGvRlrpaMJEIwFMXxFY/+PYLknIkU+Qxss402wwLy2Tv41y5oLtksiTbQjZtn+NR8Z3Ac0z3vFxQmAneqUIdpspb83n8PrqlRnGdpoNGG9BaHGWLifrmwycce5tVn/GUcRlwYS10OrTxXYnZdQV1dE4TnQpH5BOKjPMPhDQ6wFwOlaT Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Nov 05, 2026 at 11:23:41AM +0100, David Hildenbrand (Arm) wrote: > I could have sworn I saw a similar patch from Nico at some point ... maybe it > was in a private discussion. Ah, yeah, it seems a fairly obvious thing to do (as often these things are), was surprised somebody hadn't already tried it. > > > Am I correct or is the short version of this change "Remember the next scan > address per MM instead of starting from address 0 whenever we continue scanning > a MM after a skip; and we might skip under mmap lock contention" ? Yes! > > I think a lot of the commit message above can be simplified. The book author part of me comes through sometimes ;) Will try and cut it down for the respin. > > Reviewed-by: David Hildenbrand (Arm) Thanks! > > -- > Cheers, > > David -- Cheers, Lorenzo