From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D191FC433F5 for ; Fri, 3 Dec 2021 21:02:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343866AbhLCVFb (ORCPT ); Fri, 3 Dec 2021 16:05:31 -0500 Received: from mail-qv1-f41.google.com ([209.85.219.41]:44918 "EHLO mail-qv1-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243206AbhLCVFb (ORCPT ); Fri, 3 Dec 2021 16:05:31 -0500 Received: by mail-qv1-f41.google.com with SMTP id i12so3956834qvh.11; Fri, 03 Dec 2021 13:02:07 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=9Qn8OGxN0mJ4XVtOk0dKCgNrTcXxTzqRnKO2MY3F8Sk=; b=RhBdj96i+MnI0Accp1tPkhcmy/caHVjXY4sZtGG/bLGYPg0AWHQzPuMUqeQJg9lzkH ADYqZR5DLMKEbKcP7X+XT5yiu2TPfj4fiSSh3yCRHOn1+APweJlnUCLTS8garIjKuUt4 C0bV8sdP8HY41xXjw+m9nj3rB2d+Uiv8lws/JJXQhcI25KmjzwpaMIxPxq9Ws/ki0k0Z lSEEXECAwdZZozrg2N8nPhEUjVg2N0WcpOq/CUWCea+MFI5FbBWvpyKYF0bDU1Mh3il8 4Hzij9jdLFcg0AILU9Ueqc+afPx9dN8kiS9ebTxQaUYEtjuPkcHYQQwaaoBTw9NHNa+Q Fl1g== X-Gm-Message-State: AOAM531gbuLDU9q8jTsX8EEsud4q+WDE1+aKzxCI6SIfQGXWjEOOq4j9 uJddF88/qjxula+p2WsQ2/I= X-Google-Smtp-Source: ABdhPJwVSd9Ncb8R9IUZw28uewtm6Pr4Gucg24jRcXLaX+SLJpH7xPFJoA4D8MSy7KkJE2ZtK6aqJw== X-Received: by 2002:a05:6214:27e9:: with SMTP id jt9mr21965622qvb.131.1638565326487; Fri, 03 Dec 2021 13:02:06 -0800 (PST) Received: from fedora (pool-173-68-57-129.nycmny.fios.verizon.net. [173.68.57.129]) by smtp.gmail.com with ESMTPSA id n20sm2988821qkp.65.2021.12.03.13.02.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Dec 2021 13:02:06 -0800 (PST) Date: Fri, 3 Dec 2021 16:02:03 -0500 From: Dennis Zhou To: Vladimir Murzin Cc: Dennis Zhou , linux-arch-owner@vger.kernel.org, linux-mm@kvack.org, tj@kernel.org, cl@linux.com, akpm@linux-foundation.org, npiggin@gmail.com, hch@lst.de, arnd@arndb.de, linux-sh@vger.kernel.org, dalias@libc.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH] percpu: km: ensure it is used with NOMMU (either UP or SMP) Message-ID: References: <20211130172954.129587-1-vladimir.murzin@arm.com> <20211130172954.129587-2-vladimir.murzin@arm.com> <8c2b4666-cf13-3735-be1e-b8a1c71df113@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8c2b4666-cf13-3735-be1e-b8a1c71df113@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org On Wed, Dec 01, 2021 at 11:51:04AM +0000, Vladimir Murzin wrote: > Hi, > > On 11/30/21 5:41 PM, Dennis Zhou wrote: > > Hello, > > > > On Tue, Nov 30, 2021 at 05:29:54PM +0000, Vladimir Murzin wrote: > >> Currently, NOMMU pull km allocator via !SMP dependency because most of > >> them are UP, yet for SMP+NOMMU vm allocator gets pulled which: > >> > >> * may lead to broken build [1] > >> * ...or not working runtime due to [2] > >> > >> It looks like SMP+NOMMU case was overlooked in bbddff054587 ("percpu: > >> use percpu allocator on UP too") so restore that. > >> > >> [1] > >> For ARM SMP+NOMMU (R-class cores) > >> > >> arm-none-linux-gnueabihf-ld: mm/percpu.o: in function `pcpu_post_unmap_tlb_flush': > >> mm/percpu-vm.c:188: undefined reference to `flush_tlb_kernel_range' > >> > >> [2] > >> static inline > >> int vmap_pages_range_noflush(unsigned long addr, unsigned long end, > >> pgprot_t prot, struct page **pages, unsigned int page_shift) > >> { > >> return -EINVAL; > >> } > >> > >> Signed-off-by: Vladimir Murzin > >> --- > >> mm/Kconfig | 3 +-- > >> 1 file changed, 1 insertion(+), 2 deletions(-) > >> > >> diff --git a/mm/Kconfig b/mm/Kconfig > >> index d16ba92..66331e0 100644 > >> --- a/mm/Kconfig > >> +++ b/mm/Kconfig > >> @@ -425,9 +425,8 @@ config THP_SWAP > >> # UP and nommu archs use km based percpu allocator > >> # > >> config NEED_PER_CPU_KM > >> - depends on !SMP > >> bool > >> - default y > >> + default !SMP || !MMU > >> > > > > Should this be `depends on !SMP || !MMU` with default yes? Because with > > SMP && MMU, it shouldn't be an option to run with percpu-km. > > IIUC these are equivalent, truth table would not change if is under "depends" > or "default" > > SMP MMU NEED_PER_CPU_KM > y y !y || !y => n || n => n > y n !y || !n => n || y => y > n y !n || !y => y || n => y > n n !n || !n => y || y => y > I may be wrong, but I think this is slightly different as we're using #ifdef / #if defined(). > > > >> config CLEANCACHE > >> bool "Enable cleancache driver to cache clean pages if tmem is present" > >> -- > >> 2.7.4 > >> > > > > It's interesting to me that this is all coming up at once. Earlier this > > month I had the same conversation with people involved with sh [1]. > > > > [1] https://lore.kernel.org/linux-sh/YY7tp5attRyK42Zk@fedora/ > > > > I can pull this shortly once I see whatever happened to linux-sh. > > Ahh, good to know! Adding SH folks here (start of discussion [0]). I see you came > to the same conclusion, right? > Yeah, I don't see anything else from linux-sh. So I'll go ahead and apply this with my change if you're fine with that. > IIRC, RISC-V also have SMP+NOMMU, so adding them as well. > > [0] https://lore.kernel.org/linux-mm/20211130172954.129587-1-vladimir.murzin@arm.com/T/ > > Cheers > Vladimir > Thanks, Dennis