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[173.68.57.129]) by smtp.gmail.com with ESMTPSA id m9sm6753680qkn.59.2021.12.06.09.54.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Dec 2021 09:54:58 -0800 (PST) Date: Mon, 6 Dec 2021 12:54:57 -0500 From: Dennis Zhou To: Rich Felker Cc: Rob Landley , Dennis Zhou , Vladimir Murzin , 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, 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> <20211206162140.GJ7074@brightrain.aerifal.cx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211206162140.GJ7074@brightrain.aerifal.cx> X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 346C01044ABA X-Stat-Signature: z6wt3pjpgu8ntiwh44w5iwsb1t39pyir Authentication-Results: imf13.hostedemail.com; dkim=none; spf=pass (imf13.hostedemail.com: domain of dennisszhou@gmail.com designates 209.85.219.49 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-HE-Tag: 1638813300-221088 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 Mon, Dec 06, 2021 at 11:21:46AM -0500, Rich Felker wrote: > On Mon, Dec 06, 2021 at 06:01:59AM -0600, Rob Landley wrote: > > On 12/3/21 3:02 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. > > > > I can't test against current until I get some unrelated fixes from Rich Felker > > (who's been busy over the weekend), but I tested the "depends" version on 5.10 > > and got a shell prompt on my "make ARCH=sh j2_defconfig" board. > > > > Tested-by: Rob Landley > > Tested-by: Rich Felker > > I've tested the version as originally posted and it works for j2 (sh2) > (both build and runtime checked). I'd tested the other (depends > version) before and I'm fine with either going upstream. > > Rich > Thank you all for testing and bearing with me. I've applied this to for-5.16-fixes. Will send it up later in the week. Thanks, Dennis