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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8f1a328fed8sm22758066d6.16.2026.06.30.05.31.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jun 2026 05:31:51 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1weXd0-00000001ppa-1Uxh; Tue, 30 Jun 2026 09:31:50 -0300 Date: Tue, 30 Jun 2026 09:31:50 -0300 From: Jason Gunthorpe To: "Mike Rapoport (Microsoft)" Cc: Leon Romanovsky , Dennis Dalessandro , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-rdma@vger.kernel.org Subject: Re: [PATCH 1/5] RDMA/umem: ib_umem_get(): use kmalloc() to allocate page array Message-ID: <20260630123150.GB7525@ziepe.ca> References: <20260630-b4-rdma-v1-0-ab42bcf0de92@kernel.org> <20260630-b4-rdma-v1-1-ab42bcf0de92@kernel.org> Precedence: bulk X-Mailing-List: linux-rdma@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: <20260630-b4-rdma-v1-1-ab42bcf0de92@kernel.org> On Tue, Jun 30, 2026 at 01:52:29PM +0300, Mike Rapoport (Microsoft) wrote: > ib_umem_get() allocates an array of pointers to struct page for > pin_user_pages_fast() calls during memory registration. A whole bunch of these use cases in rdma are really "give me some temporary memory, I want it fast and as large as possible. In a syscall context I will free it before returning back to userspace" eg we'd be really happy to get any kind of high order page here. So, how would you feel about a new API? void *kmalloc_temporary(size_t min_size, size_t max_size, size_t *actual_size, gfp); I know of a few other cases like this in the kernel at least. The implementation could try to find an available high order page and immediately return it, otherwise do a small reclaim allocation? Jason