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[80.230.85.71]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490bc3cc140sm505952095e9.9.2026.06.08.14.16.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jun 2026 14:16:58 -0700 (PDT) Date: Mon, 8 Jun 2026 17:16:53 -0400 From: "Michael S. Tsirkin" To: Gregory Price Cc: Lorenzo Stoakes , linux-kernel@vger.kernel.org, "David Hildenbrand (Arm)" , Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Muchun Song , Oscar Salvador , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Hugh Dickins , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Ying Huang , Alistair Popple , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , Axel Rasmussen , Yuanchu Xie , Wei Xu , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , virtualization@lists.linux.dev, linux-mm@kvack.org, Andrea Arcangeli Subject: Re: [PATCH v10 12/37] mm: use folio_zero_user for user pages in post_alloc_hook Message-ID: <20260608170646-mutt-send-email-mst@kernel.org> References: <20260608154354-mutt-send-email-mst@kernel.org> <20260608161810-mutt-send-email-mst@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Jun 08, 2026 at 04:53:14PM -0400, Gregory Price wrote: > On Mon, Jun 08, 2026 at 04:30:46PM -0400, Michael S. Tsirkin wrote: > > > > > > Please consider that this is arguably the most fundamental interface in > > > in all of mm/. All we're doing is going through the process of figuring > > > out what changes here are reasonable while trying to meet your goal. > > > > > > ~Gregory > > > > I don't mind discarding all of this and doing something else completely, > > but I dislike it that multiple people are apparently now angry that I > > I wouldn't say anyone is angry, I think most folks are tripping on the > complexity of the set - which has increased (at the request of others). > > > don't address all the contradictory comments at the same time. > > Such is life in mm/ :] - it's hard to known the entire state machine, > and sometimes the contradictions aren't even wrong. > > > I thought just sending a patchset to show how the result looks like > > is easier than arguing about architecture, and would be helpful. > > > > Notice: When folks argue implementation, they largely agree the > end goal is useful. I haven't seen anyone say your problem isn't > real or that it shouldn't be addressed - just opinions on a particular > path forward (which is utterly normal here). > > Getting the right incantation of an API is really hard when the > API being changes is something that underpins the entire kernel. > > > I'm not pushing any of the mm rework, I was asked to do it, > > myself I just want the ridiculously effective optimization in there. > > > > As Lorenzo, David, and Matthew have said, the focus of the patch set > does seem to have become unweildy (in part at the request of folks > asking something be done differently). > > What needs to be done now is to break it up into some pull-ahead > sets that are easier to review. Having a brief RFC doc that lays out > the set of patches might help clarify the confusion going on here, > especially as new folks come in to ask "What's all this about?". > > As a start: > > 1) the user_addr and zeroing piece seems like a discrete > improvement worthy of its own set - aside from end goal. > > This is needed by your patch set, but was requested to > try to push us towards a more reasonable pattern for > folio_zero_user(). What I worry about is people can't agree what api they want. Simply not being an mm maintainer, I don't really have the perspective of what changes are envisioned down the road and so what api makes sense for you guys. I don't mind trying all kind of approaches, but it seems to be past the point where people feel it's costing too much of their time with all of these revisions. > 2) There are a handful of patches that seem able to pull-ahead > (some of the mempolicy stuff), either as prep work for #1 or > just on their own. > > Some of these patches seem like latent bugs that aren't hit by > current users, but do seem to be doing something subtly wrong? Right. > 3) the final virtio piece seems like it should be entirely separate > once the core pieces are done. > > It's not uncommon for core changes like this to take multiple prepatory > sets over many major versions before the final feature lands. > > ~Gregory