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b=Gz6uxsup5NvrDysGKeMXZ44qZPYIGuzbclLbViCOP9MmigNiunGxpJvcdJnlmXqRe AvBU8YwMwhCvjlAHFoATnl84QP8uDsa4o5/G2NhtFJzt0BCNE56oil5QKBjz4Ql5N2 E4pDBHs9enBiGj/gq1J1rHF0uh+0ZcV/MMTT9d7aeTnt/+LPqShw6YKXuL29ocn3HW 4sg84FuqSg5Ty/PGCMeMCWkcmYiZ/KRSXV/BOVZAtgkck9rDjLsJvr4kGeQuvmgGwP eDgZRyMDXPjrWqCYLL5Ybug/VIq8TSxZb2Pyz8B5bRFd7JLQ4veEthmtrikmpPB4mw QmDw761qL8u6w== Date: Wed, 3 Sep 2025 22:39:25 +0300 From: Mike Rapoport To: Pratyush Yadav Cc: Jason Gunthorpe , Pasha Tatashin , 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: oha8eqnzpqhufpttkqhpidi7cehmokum X-Rspam-User: X-Rspamd-Queue-Id: 3565D10000F X-Rspamd-Server: rspam01 X-HE-Tag: 1756928391-706534 X-HE-Meta: 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 hL5uzZN2 Banv/hSpLDoLyXY+Q36PEKRiZZxssmHqTVkONkhqCBtYfkHwMyzK9iKe5qyUBV3Q+4x7zkAMj4JURHweLRis36mCjR8jebYSEDxWLTo3Ml9S6ku20S/Dezv/5kBTj0atkSrwThawwtTsK/SQ9jUi6HBz9J5Vynb1Eo4PDEn89OAeT503Mjtv7qDQiH6xpfMZUGeJ0NOdmYA17HJbyXLMJxuLRrZRTqq0e5Txjg1/asul0O2201FBfXl9ccfuH7bzk4sc947se6IK5U06kSmIMo//QozEz9Y/pyCk1hi/Nzft0nuTRrYdCi0Zov3ugE4z6K44A 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: Hi Pratyush, On Wed, Sep 03, 2025 at 04:17:15PM +0200, Pratyush Yadav wrote: > On Tue, Sep 02 2025, Mike Rapoport wrote: > > > > As for porting kho_preserve_vmalloc() to kho_array, I also feel that it > > would just make kho_preserve_vmalloc() more complex and I'd rather simplify > > it even more, e.g. with preallocating all the pages that preserve indices > > in advance. > > I think there are two parts here. One is the data format of the KHO > array and the other is the way to build it. I think the format is quite > simple and versatile, and we can have many strategies of building it. > > For example, if you are only concerned with pre-allocating data, I can > very well add a way to initialize the KHO array with with a fixed size > up front. I wasn't concerned with preallocation vs allocating a page at a time, I though with preallocation the vmalloc code will become even simpler, but it's not :) > Beyond that, I think KHO array will actually make kho_preserve_vmalloc() > simpler since it won't have to deal with the linked list traversal > logic. It can just do ka_for_each() and just get all the pages. > > We can also convert the preservation bitmaps to use it so the linked list > logic is in one place, and others just build on top of it. I disagree. The boilerplate to initialize and iterate the kho_array will not make neither vmalloc nor bitmaps preservation simpler IMO. And for bitmaps Pasha and Jason M. are anyway working on a different data structure already, so if their proposal moves forward converting bitmap preservation to anything would be a wasted effort. > -- > Regards, > Pratyush Yadav -- Sincerely yours, Mike.