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Tue, 23 May 2023 17:54:44 -0700 (PDT) Date: Tue, 23 May 2023 17:54:43 -0700 (PDT) From: David Rientjes To: Matthew Wilcox cc: David Hildenbrand , Andrew Morton , Michal Hocko , Alex Shi , Johannes Weiner , Alexander Duyck , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds Subject: Re: [patch] mm, debug: allow suppressing panic on CONFIG_DEBUG_VM checks In-Reply-To: Message-ID: <703a3995-75cf-b575-deff-fe2b78bd1354@google.com> References: <53dd9df8-e88f-f466-89f9-3fa141a10267@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: C72B2C000A X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: cbymcoqa3br5t8r4denk9gcefhui3p3e X-HE-Tag: 1684889685-71883 X-HE-Meta: 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 O7zprCzA bPcieyfI/LavpyzeAC0CnB9B2HjpNfErE6L3Q0TXMVUI6btSHq5Fv3IlIfu7RfLzxAr19yJ/wq0SUFynrZyjmpP1/W5wqa1za1YVkJ7HykTPg7zrr/2R64MMWo174RY2YBd/p/DbVYOP+JpDi1ssu3fHPsHiaqnZZ2OGtxIbLVkEwDkurxnxIJUReMI4vLMCIKKiBjsgjYScgfWDUPxM2v6WwY9squeJDZ6dFxEfJn6//zdGLTjz4eTmkiXkWNb+q6a/gd2Lsu2ScPmMYKtPuH4CyE1NiLpPYnz9TI51eJQaN3aE1AnSe/asg7YXPOTzDzSpdny0r7OD9ileDAvw7sNgpXRkLMDT7qNw0aDwV/WHAU7usPrLCUXGzYRZEqcKXwg4fWCkz8GOGNNzx+7JKe/y3kcyFXr2x1Ra8 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 Tue, 23 May 2023, Matthew Wilcox wrote: > On Mon, May 22, 2023 at 11:39:27AM -0700, David Rientjes wrote: > > I think VM_BUG_ON*() and friends are used to crash the kernel for > > debugging so that we get a crash dump and because some variants don't > > exist for VM_WARN_ON(). There's no VM_WARN_ON_PAGE(), for example, unless > > implicitly converted with this patch. > > It could be added, but there's already a VM_WARN_ON_FOLIO() and > VM_WARN_ON_ONCE_PAGE(), so hopefully we just keep converting code > to folios until nobody notices that we might need such a thing. > Yeah, the lack of VM_WARN variants for VM_BUG_ON_MM or VM_BUG_ON_VMA are probably better examples. But it looks like we're converging toward eliminating VM_BUG_ON* variants entirely and relying on kernel.panic_on_warn to do the BUG_ON() behavior if we want to opt into that. So this will be a useful cleanup.