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[173.68.57.129]) by smtp.gmail.com with ESMTPSA id n19sm11202975qta.78.2021.11.30.09.41.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Nov 2021 09:41:16 -0800 (PST) Date: Tue, 30 Nov 2021 12:41:14 -0500 From: Dennis Zhou To: Vladimir Murzin Cc: linux-arch-owner@vger.kernel.org, linux-mm@kvack.org, dennis@kernel.org, tj@kernel.org, cl@linux.com, akpm@linux-foundation.org, npiggin@gmail.com, hch@lst.de, arnd@arndb.de 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211130172954.129587-2-vladimir.murzin@arm.com> X-Stat-Signature: akcroz6dor9pj3gonhx6zdbx3rh1kjyw Authentication-Results: imf31.hostedemail.com; dkim=none; spf=pass (imf31.hostedemail.com: domain of dennisszhou@gmail.com designates 209.85.160.174 as permitted sender) smtp.mailfrom=dennisszhou@gmail.com; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=kernel.org (policy=none) X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 1CECB1046306 X-HE-Tag: 1638294065-419161 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: 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. > 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. Thanks, Dennis