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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id AAE50C433F5 for ; Mon, 6 Dec 2021 08:28:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D9A076B007B; Mon, 6 Dec 2021 03:27:54 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D4A5A6B007D; Mon, 6 Dec 2021 03:27:54 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C5F606B007E; Mon, 6 Dec 2021 03:27:54 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0201.hostedemail.com [216.40.44.201]) by kanga.kvack.org (Postfix) with ESMTP id B7A416B007B for ; Mon, 6 Dec 2021 03:27:54 -0500 (EST) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 79F8D183525C1 for ; Mon, 6 Dec 2021 08:27:44 +0000 (UTC) X-FDA: 78886690848.29.655EA75 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf19.hostedemail.com (Postfix) with ESMTP id C5E0DB000093 for ; Mon, 6 Dec 2021 08:27:43 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 91607113E; Mon, 6 Dec 2021 00:27:42 -0800 (PST) Received: from [10.57.3.136] (unknown [10.57.3.136]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DDB9D3F5A1; Mon, 6 Dec 2021 00:27:39 -0800 (PST) Subject: Re: [PATCH] percpu: km: ensure it is used with NOMMU (either UP or SMP) To: Dennis Zhou Cc: 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 References: <20211130172954.129587-1-vladimir.murzin@arm.com> <20211130172954.129587-2-vladimir.murzin@arm.com> <8c2b4666-cf13-3735-be1e-b8a1c71df113@arm.com> From: Vladimir Murzin Message-ID: Date: Mon, 6 Dec 2021 08:27:44 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: C5E0DB000093 X-Stat-Signature: uuj57wtkbdojpz11e5qehnrmh796u9sg Authentication-Results: imf19.hostedemail.com; dkim=none; spf=pass (imf19.hostedemail.com: domain of vladimir.murzin@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=vladimir.murzin@arm.com; dmarc=pass (policy=none) header.from=arm.com X-HE-Tag: 1638779263-860691 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: On 12/3/21 9:02 PM, Dennis Zhou wrote: > 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. depends on !SMP || !MMU, also works for me, so feel free to amend. Thanks Vladimir > >> 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 >