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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8942e47d897sm548586d6.0.2026.01.15.09.33.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Jan 2026 09:33:15 -0800 (PST) Date: Thu, 15 Jan 2026 12:32:41 -0500 From: Gregory Price To: Yosry Ahmed Cc: Nhat Pham , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-cxl@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, kernel-team@meta.com, longman@redhat.com, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, corbet@lwn.net, gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, dave@stgolabs.net, jonathan.cameron@huawei.com, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, dan.j.williams@intel.com, akpm@linux-foundation.org, vbabka@suse.cz, surenb@google.com, mhocko@suse.com, jackmanb@google.com, ziy@nvidia.com, david@kernel.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, yury.norov@gmail.com, linux@rasmusvillemoes.dk, rientjes@google.com, shakeel.butt@linux.dev, chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, bhe@redhat.com, baohua@kernel.org, chengming.zhou@linux.dev, roman.gushchin@linux.dev, muchun.song@linux.dev, osalvador@suse.de, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, cl@gentwo.org, harry.yoo@oracle.com, zhengqi.arch@bytedance.com Subject: Re: [RFC PATCH v3 7/8] mm/zswap: compressed ram direct integration Message-ID: References: <20260108203755.1163107-1-gourry@gourry.net> <20260108203755.1163107-8-gourry@gourry.net> <4ftthovin57fi4blr2mardw4elwfsiv6vrkhrjqjsfvvuuugjj@uivjc5uzj5ys> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: D2B15140015 X-Stat-Signature: e19w46ehuo39b99u99nyiuqrkf37sw8t X-Rspam-User: X-HE-Tag: 1768498398-186186 X-HE-Meta: U2FsdGVkX18DZqoD1OaqpjMM9Yc8uh03EQs6gEJ1biSgK5ho+W/1h8OsYxuDlPhCZImr0Kdyp3Q5zVcowPxmt+UPSvZuAbxh74da+KwAl708QGnv0PQzZt4Fh9BGhWsYbXLlLiRSA/kZgv2SzUL1/6GwGh3/SuDziIN9UJY6hvv/VIm2rhYPyJOE0rmB0mJDkdP4u41+2if4uwh+ASlCWNW5+CGRIDH5HwrMK6pFX7txoRTpgPUmYWrfOQSLz57FLFOtdhSjAdHPgP+UHPagcCFtyhLIkCYeJfk0mspLqdY2xKLIq/I4gPyQUDXO3j6ZK1F0jV04ovxqwYuqrYAr2htnZTGOTKkCTYrIm1L+UH2u/lOClscbUvI2oVzK+waEGMKyNoqENt5OXzkMJn0yvt0HmQU+uv6wnpuxI48GEektiDc+P9P/nXXHE4mI/5l+cnHwfGw0IKrRBYvsx4DsdcLS6WsALxuwYYPnQ3j3OjKIM1WErGxxNoHtZ+i/XKl7hFgrc9rzbXV9Rqy/Wg0GGaCh8rL2wAKQ64e+4fS/7CdN/1/MTZ1ECE5ixmDcRSm0sjkejtitBKa8MPA4Wz+9leEccHtCY+2tSN0+y3nx9T0gpgM5tEijaeBWnkzmttQboXJFOR6ZxLLYh6SYrfKd6z8jcaotmogqnS9tzWdE8qC7RPfE2hiB7Zi17d1FjQ9qtUUzraP5bHT6+qYvLYqgY5mFVATr6BOgDsPcHQT04vesQVlCvRTH5XQsbGzvW2wtKnz6XTEFAQTQ5QlkV7W5/XBfDKMy07VrlfuHCspm1t/AEBLFZOzH5f6ATNfrDebFeUy8DESp97Zmilg3KtUn0ixqcqlwl2bAQc+rPXGZJLdntACzTKU+taoXSrWfpGTjsKPyUHBW7uPTwXp8/RtHZXKdNJZFrucbBI2K9acKfSF785bLkuFI/c50yToN8pVgixU5T/3pdsTYMZkxZX8 0elLJVbI BXB+qKg2ANxgPesZnqnH2G44pPTDCVGl3o8f5Ewh+xbNpyvrvtbkAzPj8QCBPr3gBr4a3qV7YjzYAECkTBK5BC0x6vyQOjSDApJ9HRV12PCGLNLfosVC6wX4Al1q/aJh/JheHO85TOzs+z3qkH7CtqmSSRh7SauIEjzL66ngXpyB2rt5vAF0nXEfRvRltno2qJPTRNEofH4Y/9HRR07m8YIfX6ZAzfWOBu+FO0yq7yr8GbwjHMxEPLYQC3H2iSD2AjOZAVM81mO3ZJc6ECcoG+i/lLGqh3JDjzFfexcWYy6krTWlQqiFgop94031bKijN24JZl01XVKRgzEABj2D+4hGDWJOzz+RqMbfn92j3BGYtQ5NjaCnX+L4zj4cp9zBi2H+C/ZeTfuLstsfFXkV4Qu0AgA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jan 15, 2026 at 05:00:04PM +0000, Yosry Ahmed wrote: > > > > 2. Just enable zswap shrinker and have memory reclaim move these pages > > into disk swap. This will have a much more drastic performance > > implications though :) > > I think what you're getting it as that we can still make forward > progress after memory lands in compressed cxl. But moving memory to > compressed cxl is already forward progress that reclaim won't capture if > we charge memory as a full page. I think this is the crux of the issue. > > We need to figure out how to make accounting work such that moving > memory to compressed cxl is forward progress, but make sure we don't > break the overall accounting consisteny. If we only charge the actual > compressed size, then from the system perspective there is a page that > is only partially charged and the rest of it is more-or-less leaked. Which is comically fine - because the actual capacity of the node is functionally a lie anyway :D ~Gregory