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b=oEswwnUFyX6YzOK/z9N9LFcK6410onGyQhtt7HqMPuK+Bz5kIyDe1S134VWl3YnUs lZyvI6AgrLghgDHiy98MMxoZ7WvyVFYkjxu4ggWww2iXWCZCPdO+Ia4TCZZyXyLm5D UT5oVtvwFau4bDLQtWOz7WkB//w1DzoalLjz1HHEtmXWa3UJMx17L3ErzqCldiZIxH FmdEuS2fDqllHE+JjRk/ZP9kPsJNHnxvQD2u17gru4gEjBt8mMxdpcpLAJZMg8+ot7 cItYGLq9Pi0pvmfdOGQ/cJvywzKibKRdUyepLU/iOzvdqBqn/6gndLRA0AWLDHJKG4 CiNh1699nhn3w== Date: Wed, 3 Sep 2025 22:29:56 +0300 From: Mike Rapoport To: Pasha Tatashin Cc: Jason Gunthorpe , Pratyush Yadav , jasonmiu@google.com, graf@amazon.com, changyuanl@google.com, dmatlack@google.com, rientjes@google.com, corbet@lwn.net, rdunlap@infradead.org, ilpo.jarvinen@linux.intel.com, kanie@linux.alibaba.com, ojeda@kernel.org, aliceryhl@google.com, masahiroy@kernel.org, akpm@linux-foundation.org, tj@kernel.org, yoann.congal@smile.fr, mmaurer@google.com, roman.gushchin@linux.dev, chenridong@huawei.com, axboe@kernel.dk, mark.rutland@arm.com, jannh@google.com, vincent.guittot@linaro.org, hannes@cmpxchg.org, dan.j.williams@intel.com, david@redhat.com, joel.granados@kernel.org, rostedt@goodmis.org, anna.schumaker@oracle.com, song@kernel.org, zhangguopeng@kylinos.cn, linux@weissschuh.net, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, gregkh@linuxfoundation.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, rafael@kernel.org, dakr@kernel.org, bartosz.golaszewski@linaro.org, cw00.choi@samsung.com, myungjoo.ham@samsung.com, yesanishhere@gmail.com, Jonathan.Cameron@huawei.com, quic_zijuhu@quicinc.com, aleksander.lobakin@intel.com, ira.weiny@intel.com, andriy.shevchenko@linux.intel.com, leon@kernel.org, lukas@wunner.de, bhelgaas@google.com, wagi@kernel.org, djeffery@redhat.com, stuart.w.hayes@gmail.com, lennart@poettering.net, brauner@kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, saeedm@nvidia.com, ajayachandra@nvidia.com, parav@nvidia.com, leonro@nvidia.com, witu@nvidia.com Subject: Re: [PATCH v3 29/30] luo: allow preserving memfd Message-ID: References: <20250807014442.3829950-1-pasha.tatashin@soleen.com> <20250807014442.3829950-30-pasha.tatashin@soleen.com> <20250826162019.GD2130239@nvidia.com> <20250902113857.GB186519@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: E68E14000E X-Stat-Signature: u4qz5s67io1amn4tgyub4upytit1jat1 X-Rspam-User: X-HE-Tag: 1756927821-890434 X-HE-Meta: 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 qhylofdj rNwoG1Yo4T80lkrHwuDn7ZILrwWkd4cqei0DiyY7BtiYGBSci9sVTFFziZ534MHLNP0kZe75P/hNO89Wprkq5d/z3iNvaR/FMNpzfA/x1e2uh4K7p5lfBqTZ5TOW/GsHPsIE9qfiYpovjPPrSevOG5w+t87K5j0LWxgBTV3Y4uZy79YBRp56oRSfVaDJQbBFScNrSWBnYNqFZl2nysdr0T9mEIpN1OXLd39ATpLj2V5ISSIoiartiFjYB/DKGyOh0dG934a7ajFrnM+9Y+QlhmHxAKacJ5oCvTmYqmVt4HUvIYt9mPuI5O99VkZ9uNF06hVc0kiVHtvn+VyA= 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 Wed, Sep 03, 2025 at 03:59:40PM +0000, Pasha Tatashin wrote: > > > > And again in real systems we expect memfd to be fully populated too. > > I thought so too, but we already have a use case for slightly sparse > memfd, unfortunately, that becomes *very* inefficient when fully > populated. Wait, regardless of how sparse memfd is, once you memfd_pin_folios() the number of folios to preserve is known and the metadata to preserve is a fully populated array. -- Sincerely yours, Mike.