From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 2E046C77 for ; Mon, 17 Jun 2019 13:50:37 +0000 (UTC) Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id B03E97DB for ; Mon, 17 Jun 2019 13:50:36 +0000 (UTC) Date: Mon, 17 Jun 2019 09:50:32 -0400 From: "Theodore Ts'o" To: ksummit-discuss@lists.linuxfoundation.org Message-ID: <20190617135032.GA20586@mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: [Ksummit-discuss] [TECH TOPIC] Memory management bits in arch/* List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Mike Rapoport [ Note: The following abstract was submitted via the Linux Plumbers Conference website. Per the instructions that were posted for the Maintainer's / Kernel Summit Call for Proposals[1], the proposal should also be posted on the ksummit-discuss list, so that people can comment on the proposal, and perhaps start a discussion before the summit. [1] https://lwn.net/Articles/788378/ Please note that topic proposals for both the Kernel Summit and the Maintainer's Summit are still welcome, although if you submit to the Kernel Summit track at this point, please note that you will need to have a registration to the Linux Plumbers Conference to attend. -- Ted ] There is a lot of similar and duplicated code in architecture specific bits of memory management. For instance, most architectures have #define PGALLOC_GFP (GFP_KERNEL | __GFP_ZERO) for allocating page table pages and many of them use similar, if not identical, implementation of pte_alloc_one*(). But that's only the tip of the iceberg. There are several early_alloc() or similarily called routines that do if (slab_is_available()) return kzalloc(); else return memblock_alloc(); Some other trivial examples are free_initmem(), free_initrd_mem() which were nearly identical accross many architectures until very recently. More complex cases are per-cpu initialization, passing of memory topology to the generic MM, reservation of crash kernel, mmap of vdso etc. They are not really duplicated, but still are very similar in at least several architectures. While factoring out the common code is an obvious step to take, I believe there is also room for refining arch <-> mm interface to avoid adding extra HAVE_ARCH_NO_BOOTMEM^w^wWHAT_NOT and then searching for the ways to get rid of them.