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[209.85.208.43]) by smtp.gmail.com with ESMTPSA id dk18-20020a170906f0d200b009c921a8aae2sm7214710ejb.7.2023.11.15.08.12.34 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Nov 2023 08:12:34 -0800 (PST) Received: by mail-ed1-f43.google.com with SMTP id 4fb4d7f45d1cf-5437269a661so2045737a12.0 for ; Wed, 15 Nov 2023 08:12:34 -0800 (PST) X-Received: by 2002:aa7:da07:0:b0:542:ff1b:6c7a with SMTP id r7-20020aa7da07000000b00542ff1b6c7amr5958727eds.9.1700064753769; Wed, 15 Nov 2023 08:12:33 -0800 (PST) MIME-Version: 1.0 References: <20231115154946.3933808-1-dhowells@redhat.com> <20231115154946.3933808-6-dhowells@redhat.com> In-Reply-To: <20231115154946.3933808-6-dhowells@redhat.com> From: Linus Torvalds Date: Wed, 15 Nov 2023 11:12:17 -0500 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v3 05/10] iov_iter: Create a function to prepare userspace VM for UBUF/IOVEC tests To: David Howells Cc: Christian Brauner , Jens Axboe , Al Viro , Christoph Hellwig , David Laight , Matthew Wilcox , Brendan Higgins , David Gow , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com, linux-kernel@vger.kernel.org, Andrew Morton , Christian Brauner , David Hildenbrand , John Hubbard , Huacai Chen , WANG Xuerui , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , loongarch@lists.linux.dev, linux-s390@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 03B90140027 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: u3ur8j57rnae1yapfi5order6ifgx1n3 X-HE-Tag: 1700064756-476671 X-HE-Meta: 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 WWL2fxBi 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 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: List-Subscribe: List-Unsubscribe: On Wed, 15 Nov 2023 at 10:50, David Howells wrote: > > This requires access to otherwise unexported core symbols: mm_alloc(), > vm_area_alloc(), insert_vm_struct() arch_pick_mmap_layout() and > anon_inode_getfile_secure(), which I've exported _GPL. > > [?] Would it be better if this were done in core and not in a module? I'm not going to take this, even if it were to be sent to me through Christian. I think the exports really show that this shouldn't be done. And yes, doing it in core would avoid the exports, but would be even worse. Those functions exist for setting up user space. You should be doing this in user space. I'm getting really fed up with the problems that ther KUnit tests cause. We have a long history of self-inflicted pain due to "unit testing", where it has caused stupid problems like just overflowing the kernel stack etc. This needs to stop. And this is where I'm putting my foot down. No more KUnit tests that make up interfaces - or use interfaces - that they have absolutely no place using. >From a quick look, what you were doing was checking that the patterns you set up in user space came through ok. Dammit, what's wrong with just using read()/write() on a pipe, or splice, or whatever. It will test exactly the same iov_iter thing. Kernel code should do things that can *only* be done in the kernel. This is not it. Linus