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b=A+UhL3sVc5gIJB7Tb/fyR+1oqmCAcyc7DqKW8AC++39/5gLz6Zxq5Hlb3zZeZm0Kb gd9ZOzKBSArNuwDTo1B15ZVeP5lRr/yGP2YCCo65lvrhWPhuz3+IpEgUXUFbDbznO4 SFhgXJ3vDLWAs4AP3YYtuBD89dMDH+jGL1h3jwoU= Date: Wed, 7 May 2025 15:51:23 -0700 From: Andrew Morton To: Florent Revest Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, catalin.marinas@arm.com, will@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, broonie@kernel.org, thiago.bauermann@linaro.org, jackmanb@google.com Subject: Re: [PATCH v2 0/4] mm: Avoid sharing high VMA flag bits Message-Id: <20250507155123.6ae8ee544182dc9cf1137a05@linux-foundation.org> In-Reply-To: <20250507131000.1204175-1-revest@chromium.org> References: <20250507131000.1204175-1-revest@chromium.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 2B78C20009 X-Stat-Signature: 1ukmjjqq8g98tiwpojdu147m3ej3k3k6 X-Rspam-User: X-HE-Tag: 1746658285-500723 X-HE-Meta: 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 bnYe8MNh PCeo0uqfpxNlHveftPlRsNsLsR0UrXvtsAwxrsmqPH+I0ba4cO9ONaG8+OWiH+wuucHjX387/dfAcU9DvmVQQGmSNWaLkR4FrDXmnWXNCbY1ZHq3B/uVVnDZicY2blSvslJXHcQqu4RZH2Zc8ohxtMot+yFafMyiBR/kJ6HrEBKcssuBKCpujqQPIIbCA0/8O/ir1CRwbCRDc5+XL6qWIhC0TaZJ8NdosRTRkh2Tt1fANE480gsRpObqiI3RuzWIWRfJ3RCkV3bFt8czWKFstzwEd6A== 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, 7 May 2025 15:09:56 +0200 Florent Revest wrote: > The first patch of this series is a straightforward attempt at fixing this > specific bug by changing the bit used by VM_UFFD_MINOR. I cc-ed stable on that > one and I expect it to not be all too controversial. > > The rest of the series however is a more zealous refactoring and likely to be > more contentious... :) Since this bug looks like a near miss which could have > been quite severe in terms of security, I think it's worth trying to simplify > the high VMA flag bits code. I tried to consolidate around the current usage of > VM_HIGH_ARCH_* macros but I'm not sure if this is the preferred approach here. I > really don't feel strongly about those refactorings so this is more of a > platform for discussion for people with more mm background, I'll be more than > happy to respin a v2! It's best to avoid combining backportable bugfixes with regular development patches, please. These two categories differ a lot in their timing and version-targeting. I'll queue the [1/N] bugfix targeted at 6.15 and -stable, thanks.