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Thu, 13 Nov 2025 08:56:01 -0800 (PST) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20251107210526.257742-1-pasha.tatashin@soleen.com> <20251107210526.257742-19-pasha.tatashin@soleen.com> In-Reply-To: <20251107210526.257742-19-pasha.tatashin@soleen.com> From: Pasha Tatashin Date: Thu, 13 Nov 2025 11:55:25 -0500 X-Gm-Features: AWmQ_bncXGN-eqIRVfciSwqz1sfkpOsYp0SxgOx72ZS1NRyOW1CKwiM1xe3CWB4 Message-ID: Subject: Re: [PATCH v5 18/22] docs: add documentation for memfd preservation via LUO To: pratyush@kernel.org, jasonmiu@google.com, graf@amazon.com, pasha.tatashin@soleen.com, rppt@kernel.org, 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, ptyadav@amazon.de, lennart@poettering.net, brauner@kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, saeedm@nvidia.com, ajayachandra@nvidia.com, jgg@nvidia.com, parav@nvidia.com, leonro@nvidia.com, witu@nvidia.com, hughd@google.com, skhawaja@google.com, chrisl@kernel.org Content-Type: text/plain; charset="UTF-8" > +Limitations > +=========== > + > +The current implementation has the following limitations: > + > +Size > + Currently the size of the file is limited by the size of the FDT. The FDT can > + be at of most ``MAX_PAGE_ORDER`` order. By default this is 4 MiB with 4K > + pages. Each page in the file is tracked using 16 bytes. This limits the > + maximum size of the file to 1 GiB. The above should be removed, as we are using KHO vmalloc that resolves this limitation. Pratyush, I suggest for v6 let's move memfd documnetation right into the code: memfd_luo.c and liveupdate/abi/memfd.h, and source it from there. Keeping documentation with the code helps reduce code/doc divergence. Pasha